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mrmacca
March 17th, 2010, 12:32 PM
Hi All,


This is my first post on the Vintage Computer Forum and I could do with some help or advice. Could you help, (or forward this message on to anyone who could help) diagnose my Commodore Pet 8032 display issue.

I switched it on today for the first time in a while, after the switch on beep I typed in and ran a simple program. After ten seconds random characters appeared.

This got worse resulting in permanently illuminated character positions in the whole screen with two green lines. This fills all rows and characters.

||C||o||m||m||o||d||o||r||e||||B||a||s||i||c||||4| |.0||||||||||||||||||||||||||||||||||||
|||||||||||||||||||||||||||||||||||||||||||||||||| |||||||||||||||||||||||||||||||||||||||||||||||||| |||||||
||R||e||a||d||y||||||||||||||||||||||||||||||||||| |||||||||||||||||||||||||||||||||||||||||||||||||| ||||

Without taking a picture this is the best pictorial way I can describe it. :eh:


You can still make out the program running amongst the unwanted illumination but the display now is awful making the Pet unusable really. Shame really the board is from 1980 and I have the top off. Someone’s suggested re seating the character rom but I have no idea which chip it is?

I’d love to fix this computer and I work at a University so any ideas of rectification, how ever complicated I am sure we have the technology to follow or I could get someone at work to interpret anything you suggest if I dont understand ;)

Many thanks for your time, :D

Kind Regards

Alasdair Macdonald
Staffordshire University, UK.
maccatakker69@googlemail.com

cosam
March 17th, 2010, 01:08 PM
Do the vertical bars run through the other characters too? That would suggest a stuck bit on the character ROM and reseating may indeed help. From what I can make out, the character ROM is at position UA3 (i.e. the third chip on row "A", which should be marked on the board).

geoffm3
March 17th, 2010, 01:10 PM
My guess is that these are flakey display RAM chips... the 8032 uses 2114 for display RAM, and they are notorious for going bad in a variety of different machines. If they are socketed you can try swapping them out and see if the symptoms change. Should be a couple of them at UC4 and UC5 (per schematics).

mrmacca
March 17th, 2010, 09:51 PM
Hi Guys,

Many thanks for both your replies. I shall get together with a colleague at work hopefully today and see if we can resolve. He used to work on them and being older than me is way more knowledgeable.

Just to clarify, the screen worked fine for only ten seconds then permenantly stayed illuminated incorrectly as above, the bars run the entire length and height filling the screen.

I could take some pictures today hopefully.

Thanks, Alasdair.

dave_m
March 17th, 2010, 10:11 PM
Alasdair,
I don't think the video RAM can cause these types of vertical lines so the problem must be somewhere from the character generator out to the analog video board. The character generator drives a serial shift register that creates the dot patterns that will have to be checked. Do you have an oscilloscope?
-Dave

mrmacca
March 18th, 2010, 12:08 AM
Gosh we do have an ossiloscope but as you can see I can't even spell it let alone use it. There are plenty of people here that can luckily.

I have taken some pictures this morning so I can show you exactly what I am talking about.
Am I allowed to upload them to here or I could use photbucket links perhaps? :confused:

The board is an has a serial number of 803425 80 Column CPU 8032080 - 1980 - Made in Japan

I can see UDA3 it says MOS on top - I may try removing and re seating this then?
UDA4 and UDA5 are soldered in. A little more tricky to do anything with I fear ?

Thanks for all your replies, really appreciated. Alasdair in the UK>

mrmacca
March 18th, 2010, 12:18 AM
My guess is that these are flakey display RAM chips... the 8032 uses 2114 for display RAM, and they are notorious for going bad in a variety of different machines. If they are socketed you can try swapping them out and see if the symptoms change. Should be a couple of them at UC4 and UC5 (per schematics).

UC4 and UC5 are soldered in smaller chips Geoff :(

cosam
March 18th, 2010, 02:17 AM
I have taken some pictures this morning so I can show you exactly what I am talking about.
Am I allowed to upload them to here or I could use photbucket links perhaps? :confused:
Yes, you can upload pictures as attachments to your post (you will need to "Go Advanced" if you're doing a "Quick Reply" and click on the paper clip icon). Linking to an external image is also fine (Click on the picture frame/tree icon).


I can see UDA3 it says MOS on top - I may try removing and re seating this then?
Most of the big chips will probably say MOS on them. Does your board look like this one (http://www.classiccmp.org/dunfield/pet/h/pet8032o.jpg)? If so I'd suspect the character ROM is the one on its own in the bottom left corner. You don't necessarily need to remove it completely to reseat it, just enough to loosen it, then push it back home.

If that doesn't help, try putting the scope (actually a simple volt meter would do) on the data pins (9-11 and 13-17) of the ROM to see if any are stuck high.


UDA4 and UDA5 are soldered in. A little more tricky to do anything with I fear ?
According to these schematics (http://zimmers.net/anonftp/pub/cbm/schematics/computers/pet/8032/index.html), the video RAM is UC4 and UC5, but it wouldn't surprise me if they were soldered in. I wouldn't worry about that just yet.

mrmacca
March 18th, 2010, 05:17 AM
Well I removed and reseated UA3 to no avail. Still the same. :tellme:

I think the next move is to up load my pictures. I do have a similar board to the one linked, however it looks less complex and there is no expansion cards in it. There is the expansion card sitting next to the machine (not connected to the main board) and I can't remember why it is out? I presume this is unrelated info.

I think pictures may help with the diagnosis. Bear with, thank you, and don't give up on me. :)

mrmacca
March 18th, 2010, 11:07 AM
Hi Guys I have some pics and thought if I may upload a couple?

Note that the pic makes it looks like I have simply increased the brightness on the rear of the screen, I haven't it is unwanted lines which dont go away.
Here goes :

http://i117.photobucket.com/albums/o65/maccatakker69/pet/pet1.jpg

http://i117.photobucket.com/albums/o65/maccatakker69/pet/board1.jpg

geoffm3
March 18th, 2010, 11:31 AM
Interesting problem. I sat down with pen and paper and figure that to display the text properly then every bit lane of the video ram should be correct, so my original idea is probably not right. The only character that seems wrong is the space. Have you tried inputting in a bunch of text from the keyboard to see if there are any other characters that are incorrect? Might be worth writing a quick BASIC program to output all the different PETSCII characters and see if there are any others that are not right.

mrmacca
March 18th, 2010, 11:38 AM
I can try tommorow, the pets at work and I'm at home. I presume all the keys worked before and after.

Can you see what I mean about lines now.

|||||||||||||||U|P|S|E|T|T|I|N|G|||||||||||||||||| |||||||||||||||||||||||||||||||||||||||||||||||


:whaasup:

mrmacca
March 18th, 2010, 11:40 AM
Here she is :

http://i117.photobucket.com/albums/o65/maccatakker69/pet/DSCF0140.jpg

http://i117.photobucket.com/albums/o65/maccatakker69/pet/DSCF0144.jpg

Whats this bit? Its not attached ?

http://i117.photobucket.com/albums/o65/maccatakker69/pet/DSCF0147.jpg

http://i117.photobucket.com/albums/o65/maccatakker69/pet/DSCF0143.jpg

http://i117.photobucket.com/albums/o65/maccatakker69/pet/DSCF0149.jpg

geoffm3
March 18th, 2010, 12:00 PM
Looks like a ROM switcher.

mrmacca
March 18th, 2010, 12:04 PM
will it fix it? lol

:inlove:

geoffm3
March 18th, 2010, 12:18 PM
One can only hope. :)

Is there a connector on the back of that board, or does it just have the SIP connector coming off the side?

mrmacca
March 18th, 2010, 12:38 PM
On that little board which has a home made switch attached to it it looks like it should connect into the top of the board. It wont go in the back of the pet (like the old zx81ram pack style) :)

I have a whole inventory of the history of computers here at the uni. We have all the gear but no idea lol :)

dave_m
March 18th, 2010, 01:36 PM
With perhaps a little help from members of this forum, you will get this fine old computer repaired. I have an 8032 also and can help with comparison waveforms later if needed.

There is a lot of good information on the web about the PET computers. Here are two sites but remember that there are many different models of PETs. Restrict your research to the 8000 series computer with BASIC 4.

http://zimmers.net/anonftp/pub/cbm/pet/index.html

http://6502.org/users/andre/petindex/index.html

cosam
March 18th, 2010, 03:06 PM
Yes, the little expansion board is a ROM switcher which fits in a socket on top of the board. I don't think it has anything to do with your problem though. It would be an interesting thing to try out when the computer is otherwise working properly.

One thing to try would be replacing the character ROM with another with the same pinout (one of those on the ROM switcher may fit, but check it's the same pinout first). You will likely get utter garbage on the screen, but if the lines remain it's likely that UA2 (the shift register Dave mentioned) is bad. If the lines disappear, it's probably the character ROM itself. If you can confirm that's the case, I may even have an original replacement ROM for you.

tezza
March 18th, 2010, 04:45 PM
Looks like a fine machine. Certainly worth putting some effort into getting it going properly.

Tez

mrmacca
March 18th, 2010, 10:24 PM
Thats guys for taking the time to reply. I'll have a look today and see if the chips are interchangable. Can I do any damage if the chips aren't identical?

Definatly worth saving isn't it :)
If I get a chance soon I could take some pics of the other vintage computers we have here.

mrmacca
March 18th, 2010, 10:45 PM
Just thinking if you do have some replacement chip/s I could try I wonder if with the magic of paypal you would consider posting and I could try some?
I've looked on ebay and the net but I don't think I'll be getting spares for this one very easily! I'm guessing you all may not be in the UK due to the reply time lag?

Would this be a good purchase to try chips out of or is it a totally different system?

http://cgi.ebay.co.uk/PET-COMMODORE-3016-SPARES-REPAIR_W0QQitemZ190380281550QQcmdZViewItemQQptZUK_ VintageComputing_RL?hash=item2c538c8ece

carlsson
March 18th, 2010, 10:54 PM
I still have a bag of various PET motherboards, of which some definitely are 8000 series. Most of them have been marked as broken but may have salvagable chips. I can have a closer look in the weekend to come, and will await any other expert advice which chips or items to suspect. If we come up with something useful, you'll have it for postage + PP fees.

The PET on eBay is a 3000 series one with 40 column display and older Basic. While I think the character ROM is the same, for most part other chips won't be.

mrmacca
March 18th, 2010, 11:50 PM
Thanks Anders, This Pet really have sentimental value too so I really would love it to be right again. :)

I'll pop that character rom out today, if I switch it on without it present and the lines dissapear would this help or would the whole pet just sit in a dead state?

cosam
March 19th, 2010, 12:56 AM
I'll pop that character rom out today, if I switch it on without it present and the lines dissapear would this help or would the whole pet just sit in a dead state?
I was just wondering about that whilst reading through the other replies. It's not an exhaustive test, but if the lines are there with no ROM at all, you can be pretty sure the ROM isn't the problem. If there are no lines, it's likely the ROM is bad, but not 100% certain.

I would recommend properly diagnosing the fault before sourcing replacement parts. Swapping parts out isn't a bad approach if you happen to have an identical working machine to borrow bits from, but when each part needs to be ordered/shipped individually it can become pretty frustrating. If you're lucky it's only the character ROM that's bad, but these problems often have a recursive nature - just when you think you've fixed it, another problem suddenly becomes apparent. Replacing soldered-in chips isn't something most people do just for the fun of it, either ;-)

PS. Most of us have our locations in our profiles, which can be seen at the top-right of each post. Some of your replies couldn't have come from much further away from the UK! ;-)

mrmacca
March 19th, 2010, 12:58 AM
More fiddling this morning.

I removed and reseated all the mid sized chips to no avail.

I'm leaving out UD11 as it seems to be irrelevant,

Take out UA3 and the whole screen fills totally green. Put it back in same two lines per character.

Take out UD 10 - Lines remain but loose basic
Take out UD 9, 8 or 7 and you get nothing at all from the machine.

I'm still thinking UA3 ROM is the culprit, dunno why :(

mrmacca
March 19th, 2010, 01:03 AM
Thanks Steve,

I see now, your from the Netherlands. Cool Place. Do you code on Homebrew? (I think its a great peice of code) :)

cosam
March 19th, 2010, 01:11 AM
Thats guys for taking the time to reply. I'll have a look today and see if the chips are interchangable. Can I do any damage if the chips aren't identical?
You could potentially do damage to the chip, the rest of the computer, or both. Best to be sure the chips are compatible to be on the safe side. You can use either 2316 or 2332 ROMS/EPROMS. The ones on the ROM switcher may be completely different types. Any of the ROMs on the board should work though; removing them may result in the computer not booting, but that shouldn't matter for this test.

mrmacca
March 19th, 2010, 09:10 AM
Well back with the camera. I've had all of the socketable chips out and back in (as described 3 posts before) I do keep coming back to this character rom :(

I've looked through some drawers and found lots of old chips of the era but nothing exact I could use. Lots of Intel chips circa 1974-79!

http://i117.photobucket.com/albums/o65/maccatakker69/pet/DSCF0155.jpg

http://i117.photobucket.com/albums/o65/maccatakker69/pet/DSCF0154.jpg

http://i117.photobucket.com/albums/o65/maccatakker69/pet/DSCF0153.jpg

http://i117.photobucket.com/albums/o65/maccatakker69/pet/DSCF0152.jpg


So now with officially no spares to try I am a bit stuck, heres a better pic of my woes

http://i117.photobucket.com/albums/o65/maccatakker69/pet/DSCF0157.jpg

dave_m
March 19th, 2010, 09:18 AM
Take out UA3 and the whole screen fills totally green. Put it back in same two lines per character.
I'm still thinking UA3 ROM is the culprit, dunno why :(

I agree, the 'cosam' test indicates the character generator ROM is the leading candidate. To prove it, can you borrow a can of "circuit cooler" spray from your electronics engineering department? Spray a little on UA3 and if all clears up, you know it is a temperature problem with UA3. Here is a link to information on this spray: http://mgchemicals.com/products/403a.html

If this is the problem, some of us here will have a replacement ROM or can program a 2532 EPROM chip to replace it. We must keep the PETs alive!
-Dave

carlsson
March 19th, 2010, 09:52 AM
I suppose I'll be able to mail a character ROM for about £2 including fees. Question is if anyone can do it quicker and cheaper, e.g. within the UK.

mrmacca
March 19th, 2010, 09:56 AM
Like wise if any of the chips I have will help I'll post them on :) Not sure you can make the numbers out in the pics.

There can't be that many PETS still alive can there?

I'm not too sure how to reprogram an eprom. If anyone will willing to post me a ROM I could PayPal them and post return it if it doesn't help me.

mrmacca
March 19th, 2010, 09:57 AM
I suppose I'll be able to mail a character ROM for about £2 including fees. Question is if anyone can do it quicker and cheaper, e.g. within the UK.

That would be great if you could?

MikeS
March 19th, 2010, 10:53 AM
I agree, the 'cosam' test indicates the character generator ROM is the leading candidate.
<snip>
-Dave
I don't follow the logic; can't hurt to replace it I suppose, but why do you suspect the CG ROM (other than that it's socketed and easy to replace ;-) ?) I don't see what removing it proves or even how it could be the CG ROM anyway, especially since the bars are darker than the text.

But if any of those chips in the drawers happen to be 2532s (especially the purple ones with the round labels) and they're not blank, then I'd think that replacing the CG with one of those would prove something one way or another.

dave_m
March 19th, 2010, 11:03 AM
I don't follow the logic; can't hurt to replace it I suppose, but why do you suspect the CG ROM (other than that it's socketed and easy to replace ;-) ?)

Mike,
Well, I'll admit the socketed part has something to do with it :) , but since the vertical lines are within the character boundries, it can not be the screen RAMs. It might be the serial shift register with stuck bits. What do you think?
-Dave

mrmacca
March 19th, 2010, 11:46 AM
Of course we could treat it like any modern peice of technology and swap the whole motherboard for a working one :D

I've got PayPal remember people if you've got such a board :mrgreen:

I know, I can here you all thinking wheres the fun in that. But for a newbie like me even that would be interesting :listen:

MikeS
March 19th, 2010, 11:48 AM
Mike,
Well, I'll admit the socketed part has something to do with it :) , but since the vertical lines are within the character boundries, it can not be the screen RAMs. It might be the serial shift register with stuck bits. What do you think?
-DaveI think I'm out to lunch; the apparent difference in brightness misled me, but you're right: it's almost definitely the CG ROM or, less likely, the shift register. I can duplicate the problem by lifting a couple of pins on the CG.

mrmacca
March 19th, 2010, 11:51 AM
You are all genius's but then I guess you probably know that :mrgreen:

carlsson
March 19th, 2010, 11:52 AM
Great idea to look for a spare 2532. As long as it is not entirely blank, something will show on screen. It may be complete garbage, but it would be static garbage without the lines. If so, we can be quite certain this chip needs a proper replacement. If the lines appear anyway, you have a different fault that needs diagnosing before solving it.

mrmacca
March 19th, 2010, 11:55 AM
My collegue did look through all these chips and draw a blank. H'es got a good 15 years more experiance then me.

I can't rummage through them now as everything is at work.

MikeS
March 19th, 2010, 12:24 PM
Look familiar? (2 pins lifted on CG ROM)


3334

MikeS
March 19th, 2010, 12:28 PM
My collegue did look through all these chips and draw a blank. H'es got a good 15 years more experiance then me.

I can't rummage through them now as everything is at work.
Never mind; if Carlsson or someone sends you a replacement 8032 CG ROM you'll probably be in business.

But we're curious: what *are* those pretty purple ones with the round labels?

mrmacca
March 19th, 2010, 12:28 PM
Very Very Clever Mike

http://i297.photobucket.com/albums/mm231/joorge_photos/emoticons/smiley-bow.gif

So Fab Forum'ers as a novice (but one who works at a Uni and obviously have stuff around which may or may not help) where do we go from here?

:) I'm really pleased to see the error replicated above Mike :)

mrmacca
March 19th, 2010, 12:36 PM
Never mind; if Carlsson or someone sends you a replacement 8032 CG ROM you'll probably be in business.

But we're curious: what *are* those pretty purple ones with the round labels?

I'll relook at work and get any numbers off them. Theres a yellow, orange and blue circular ones :P

Shall I take my camera into work next week and take a pic of some of the old bits we have on display or is that just "done to death on here"?
We've got everything from Galaxy 2000's to punch card readers lol

MikeS
March 19th, 2010, 01:44 PM
Very Very Clever MikeHey, your intuition was right on! There's a future in troubleshooting PETs waiting for you...


So Fab Forum'ers as a novice (but one who works at a Uni and obviously have stuff around which may or may not help) where do we go from here?Well, if you have the facilities to erase and (re)program EPROMs and somewhere in those drawers you find a 2716, 2532 or a TI 2516 (check the chips with 24 pins and a window) then you download the appropriate image (901447-10) from one of several sites and program a new EPROM with it. Failing that, you ask one of the generous and helpful folks on here like Anders and Steve to send you one (I would and Dave probably would as well, but it'd take a while; I assume someone closer can help).

AFAIK those three EPROM types should work (as well as an original ROM of course); if someone knows otherwise, please correct me.

MikeS
March 19th, 2010, 01:47 PM
I'll relook at work and get any numbers off them. Theres a yellow, orange and blue circular ones :P

Shall I take my camera into work next week and take a pic of some of the old bits we have on display or is that just "done to death on here"?
We've got everything from Galaxy 2000's to punch card readers lolWe all love to drool over pictures of neat old stuff, but if there are more than two or three it might be better to put them on one of the numerous free photo sites and just post a link here. Looking forward to seeing what you've got there!

mrmacca
March 19th, 2010, 02:01 PM
ok dokey, I shall ask a few guys around work if we have the technology to Programme one of the chips. That would be the coolest solution wouldn't it :)

But if they couldn't I might please come and beg one from one of you. I guess I am in no real rush, the machine is 30 years old already hey.
Next week I'll try and snap some old stuff for you and I'll load it up on photobucket, perhaps make a new thread.

thanks to you all for the help so far, Loggin out as its the end of the night.

dave_m
March 19th, 2010, 02:34 PM
where do we go from here?

Alasdair,
Using the Private Message (PM) capability of this forum, send Anders your shipping address and ask for how he wants the 2UK paid (paypal, etc or maybe in EPROMs if you have the kind he wants). Address the PM to "carlsson".

Best regards,
Dave

carlsson
March 19th, 2010, 02:35 PM
Yup. I'll have a look tomorrow. Almost all my PET stuff is in the basement, both complete machines and spare items. Fortunately I have two programmers of which at least one handles 2532 so I'll be able to read any chip I can find. Quite possibly though these will be 2532 EPROMs loaded with a Swedish font, but it would be a quick fix for me to reprogram one of my blank 2532's with the International font instead.

cosam
March 19th, 2010, 02:59 PM
I still think it'd be worth taking two minutes to try another ROM in the CG socket - as far as I can tell, any of the other ROMs on the board would do. The reason is that a broken shift register could cause exactly the same symptoms. If Mike wants to get his soldering iron out and lift a couple of inputs on the 74166 I'm sure he could reproduce the above screen shot yet again ;-) My money is also on the ROM being toast, but it would be a shame to fit a new one just to find out that it's the shift register that needs replacing (and that the original ROM was probably perfectly good from the start!).

MikeS
March 19th, 2010, 04:23 PM
I still think it'd be worth taking two minutes to try another ROM in the CG socket - as far as I can tell, any of the other ROMs on the board would do. The reason is that a broken shift register could cause exactly the same symptoms. If Mike wants to get his soldering iron out and lift a couple of inputs on the 74166 I'm sure he could reproduce the above screen shot yet again ;-) My money is also on the ROM being toast, but it would be a shame to fit a new one just to find out that it's the shift register that needs replacing (and that the original ROM was probably perfectly good from the start!).I second the motion. The ROM is more likely to be the cause of the problem, but it could indeed be the 74166 at UA2; removing the CG ROM doesn't really prove anything since it just lets all the data lines float high including the two that are probably stuck high already, but another ROM would most likely pull those lines low somewhere in the CG table so if the bars disappear that would indicate that the SR is OK and it must be the ROM.

Try the irrelevant UD11 or even UD10. I assume that since it failed while just running, a broken or bent pin is not the problem; be careful not to bend/break any pins now though!

tezza
March 19th, 2010, 06:02 PM
Great thread guys!

Although I can't contribute much, these deductive exercises are educational. The solution appears close.

Tez

dave_m
March 19th, 2010, 06:34 PM
Guys,
One possibility we did not consider is a cold solder joint under the Character Generator ROM socket. But I think the "MikeS test" indicates that it would take two cold solder joints which would lower the probability of that being the problem. So I guess we all agree that if no other tests are performed, we will replace the ROM?

Tez, yes this has been fun.

mrmacca
March 19th, 2010, 09:34 PM
I second the motion. The ROM is more likely to be the cause of the problem, but it could indeed be the 74166 at UA2; removing the CG ROM doesn't really prove anything since it just lets all the data lines float high including the two that are probably stuck high already, but another ROM would most likely pull those lines low somewhere in the CG table so if the bars disappear that would indicate that the SR is OK and it must be the ROM.

Try the irrelevant UD11 or even UD10. I assume that since it failed while just running, a broken or bent pin is not the problem; be careful not to bend/break any pins now though!

Don't forget my earlier attempt to remove each socketed chip at a time I'll repost incase the line with UD11 was relevant

I removed and reseated all the mid sized chips to no avail.

I'm leaving out UD11 as it seems to be irrelevant, (and its still out)
Take out UA3 and the whole screen fills totally green. Put it back in same two lines per character.
Take out UD 10 - The Green Lines remain but I loose the basic 4.0 output leaving just the lines.
Take out UD 9, 8 or 7 and you get nothing at all from the machine. (and the screen is totally empty without the green lines either)


I'm concerned about that chip that was at UD11, it had a soldered pin on it and some hand written writing. The machine obviously has had more owners then myself in its time. I'm a novice but do worry about moving chip locations incase it ends up with the whole board going pop!

I'd be really happy to take Anders kind offer and will send him a short PM.

dave_m
March 19th, 2010, 10:19 PM
No to worry about the PROMS in UD11 (address hex A000) or UD12 (address hex 9000), they are for user installed machine language programs and are not part of the operating system. The code there can not be executed without being called with a SYS command. Mike was just suggesting that the chip at UD11 would be a good candidate to drop into the character generator spot as it is pin compatible and is not needed by the operating system. The actual code in the chip was irrelevant for this test. But if you think the chip may have a problem, do not use it. It is OK to leave it off the system board.

The soldered pin may have been attached to the chip as a test point to clip-on a scope lead.

I agree, at this point in the testing, it is best to make arrangements with Anders. For a few quid, it is a very good deal. The 2532 EPROM is worth more than that without the programming.

mrmacca
March 19th, 2010, 11:32 PM
No to worry about the PROMS in UD11 (address hex A000) or UD12 (address hex 9000), they are for user installed machine language programs and are not part of the operating system. The code there can not be executed without being called with a SYS command. Mike was just suggesting that the chip at UD11 would be a good candidate to drop into the character generator spot as it is pin compatible and is not needed by the operating system. The actual code in the chip was irrelevant for this test. But if you think the chip may have a problem, do not use it. It is OK to leave it off the system board.

The soldered pin may have been attached to the chip as a test point to clip-on a scope lead.

I agree, at this point in the testing, it is best to make arrangements with Anders. For a few quid, it is a very good deal. The 2532 EPROM is worth more than that without the programming.

If it helps the diagnosis I can give it a go... If there are any chips I could help with alternatively if you think I may have some here that people could use? I'll try and note down some I have.
:D

carlsson
March 20th, 2010, 07:39 AM
Actually I went through my boards this morning and noticed they all have 2716 EPROMs. This makes sense since the PET character set is only 2K and the reverse half is generated by the CPU, unlike later VIC/C64 which has a 4K character set. Since I already have piles of 2516 and 2716 chips, I will take one of my loose ones and reprogram with the proper character set instead of pulling a chip from a board - in particular since that chip would hold a slightly different character set than what our friend ultimately needs.

And yes, I got a PM which I will handle shortly.

mrmacca
March 20th, 2010, 09:38 AM
Great news, all went smoothly with the PM :)

Thanks Anders, makes sense to swap for exactly the right character set hey. Its exciting breathing life back into these old girls isn't it :cool:

MikeS
March 20th, 2010, 10:17 AM
Actually I went through my boards this morning and noticed they all have 2716 EPROMs. <snip>
Since I already have piles of 2516 and 2716 chips,<snip>
That's why I said to look for 2716s and TI 2516s as well as 2532s; this discussion seemed to assume that the CG ROM is a 4K 2332/2532 type instead of the much more common 2K 2716 type (probably because of the suggestions to replace it with a 4K ROM from elsewhere for testing).

I doubt that you have any, but watch out for TI's non-standard 2716s; on the other hand if it weren't for their non-standard 2532 we wouldn't have straight replacements for the 2332s in the PETs and elsewhere...

http://www.tomshardware.com/forum/80532-13-what-diff-eprom-eprom

MikeS
March 20th, 2010, 10:24 AM
While we're on the 2K/4K topic:

Has anyone ever read or done anything about exploiting the alternate character set that's provided for in the 4032/8032 PETs?

carlsson
March 20th, 2010, 01:52 PM
Alternative set? Do you mean those boards originally had a 4K ROM, but in mine the importer (likely Datatronic or reseller) installed 2K EPROMs with Swedish character set?

Actually I had some idea about designing my own character set and use instead of the original one. For instance the C64 character set would be a good candidate and give characters with wider vertical lines.

As for my 2 kB chips collection, those are five TMS2516, seven MM2716Q, four OKI MSM2716AS plus a single one each of AMD 2716 and NEC D2716D. All OKI's but only one of the MM2716Q's has gold plated legs. In this case I don't know if it preferred or not.

dave_m
March 20th, 2010, 03:53 PM
Alternative set? Do you mean those boards originally had a 4K ROM, but in mine the importer (likely Datatronic or reseller) installed 2K EPROMs with Swedish character set?


Anders, I doubt that the machines came with 4K character generator ROMs. But if you chose to install a 4K EPROM, the design supports the capability of switching between two 2K character sets. There is a line from the CRT controller called Character Option that is connected to pin 18 of the ROM. If the ROM is a 2K part, pin 18 is just an extra chip enable, but in a 4K ROM, it is address line A11 which allows addressing of the upper 2K ROM space. I suppose it could be used under program control to switch between the Swedish character set and any other set.

carlsson
March 20th, 2010, 04:52 PM
Ooh.. that was new knowledge to me. I was happily surprised when I spotted a 40 column PET that boots up in lower case, but afterwards I realized they all (?) actually have both upper and lower cases, selectable through CHR$ or a POKE.

mrmacca
March 20th, 2010, 10:29 PM
I just wanted to publicly thank Anders Carlsson for sourcing and arranging for me a couple of chips to try. :super:

I hope you all agree, Its turned into a really interesting thread, I apologise that I can't contribute personally but I admire all your technical knowledge.

As soon as the post arrives I shall trial Anders replacement and let you know the results.

:workout2:

polishedball
March 21st, 2010, 02:33 PM
Well this thread inspired me to pull out my 3 dead 8032 boards and get them repaired, sadly when i booted the 8032 it chirped flashed and died. Now I have 4 boards to repair.

I didn't see it mentioned but this company seemed a great source of parts not sure if they ship international or not. http://www.unicornelectronics.com I was able to get the 2532's and 2716's (luckily my BK programmer handles them) along with all the logic and 6500 chips. So hopefully i'll get mine up an running.

dave_m
March 21st, 2010, 07:24 PM
Well this thread inspired me to pull out my 3 dead 8032 boards and get them repaired, sadly when i booted the 8032 it chirped flashed and died. Now I have 4 boards to repair.


Oh, that's not fair. The beep meant it passed its power on check, but then apparently the PET expired. Tell us what the condition is now. White screen, dark screen, garbage screen, no response, etc.
Do you have a voltmeter to check the power supply voltages?

tezza
March 21st, 2010, 07:58 PM
All these Pets dying....

Maybe I should pull mine out again just to give the circuits some exercise? ;)

Knowing my luck I'll immediately have an issue. This is to stop me getting bored of course... :tellme:

Tez

mrmacca
March 22nd, 2010, 01:28 AM
I wonder how many working models are left? Anyone care to hazard a guess?

I'm going for... hmm... 450

to high? :lookroun:

cosam
March 22nd, 2010, 01:53 AM
That's why I said to look for 2716s and TI 2516s as well as 2532s; this discussion seemed to assume that the CG ROM is a 4K 2332/2532 type instead of the much more common 2K 2716 type (probably because of the suggestions to replace it with a 4K ROM from elsewhere for testing).
Yeah, I've been flying on instruments at this end - I only have the schematics to look at and the CG is marked as "2316 or 2332" and all others are one or the other. I can never remember which 27xx and 25xx are equivalents ;-) A 4K ROM in a 2K socket should still work though, and it also explains:


But if you chose to install a 4K EPROM, the design supports the capability of switching between two 2K character sets. There is a line from the CRT controller called Character Option that is connected to pin 18 of the ROM. If the ROM is a 2K part, pin 18 is just an extra chip enable, but in a 4K ROM, it is address line A11 which allows addressing of the upper 2K ROM space. I suppose it could be used under program control to switch between the Swedish character set and any other set.
Which is new to me too, sounds like a cool feature.


All these Pets dying....
It does seem that a lot are reaching their use-by date all of a sudden, doesn't it? Or maybe the number of PET repair threads here is drawing Googlers to this forum ;-) Does make me wonder how many machines may have been discarded as "junk" whilst actually being quite easily repairable.

Anyway, here's hoping the new CG winging its way to the OP will help save this PET from such a bitter end. My going-on about testing the shift register will probably be enough to ensure that there's absolutely nothing wrong with that part ;-)

dave_m
March 22nd, 2010, 07:27 AM
All OKI's but only one of the MM2716Q's has gold plated legs. In this case I don't know if it preferred or not.

Anders,
My guess is that if the part was destined to be soldered into a board, a tin plated lead would be best.

But if the part was meant for installation into a socket, the gold plate would best. Gold has good electrical properties plus it does not tarnish easily.
-Dave

MikeS
March 22nd, 2010, 08:42 AM
I wonder how many working models are left? Anyone care to hazard a guess?

I'm going for... hmm... 450

to high? :lookroun:If you count all models I think you'd be surprised; I know of about 25 just among three or four local friends and I wouldn't be surprised if there were a hundred or more just in the greater Toronto area. After all, any collection of significant vintage computers has to include at least one PET.

Bo Zimmer, Steve Gray, Jim Brain and Anders alone probably have 450 units among them ;-)

Don't forget that many thousands were put into schools, at least in Canada and the US.

Mind you, considering the current theme of this thread maybe instead of "working" we should say "working the last time they were turned on" ;-)

MikeS
March 22nd, 2010, 09:12 AM
Anders, I doubt that the machines came with 4K character generator ROMs. But if you chose to install a 4K EPROM, the design supports the capability of switching between two 2K character sets. There is a line from the CRT controller called Character Option that is connected to pin 18 of the ROM. If the ROM is a 2K part, pin 18 is just an extra chip enable, but in a 4K ROM, it is address line A11 which allows addressing of the upper 2K ROM space. I suppose it could be used under program control to switch between the Swedish character set and any other set.As a matter of fact there is a 4K Swedish Character Generator ROM for the SuperPET on Zimmer's ;-)

But I was wondering if the alternate character set was ever used for anything other than the SuperPET's APL characters. I had (have) an alternate set in my old 2001 but it was selected with a switch; never got around to looking at how they're selected on the 8032 etc.; presumably just a poke to one of the CRTC registers.

I kind of got interested in this during a discussion on another forum about Japanese character sets; I've got a Japanese keyboard and my girlfriend is studying Japanese so I thought it'd be fun to have a Japanese PET, and that would require using the upper 2K of the CG space.

Anybody ever see an article in any of the mags about playing with this? I'd be surprised if there weren't any.

dave_m
March 22nd, 2010, 09:39 AM
Mike,
No I haven't but having the right keyboard to sure a good start for this project. Have you seen the info on the VIC-1001, the Japanese VIC?

http://zimmers.net/cbmpics/cvic1001.html

-Dave

MikeS
March 22nd, 2010, 10:10 AM
Mike,
No I haven't but having the right keyboard to sure a good start for this project. Have you seen the info on the VIC-1001, the Japanese VIC?

http://zimmers.net/cbmpics/cvic1001.html

-DaveYeah; I think that's where one version of the Japanese character set for the PET came from. A fellow in Tokyo has a Japanese PET that died and in his investigations he made a new CG ROM from the Japanese VIC set; I've got a version installed in my 2001 PET as a switch-selectable alternate 2K set.

It would be nice though to have access to upper and lower case, PET graphics, and the alternate character set all on the same screen; I suspect it's not possible with standard hardware but I'm thinking that maybe I could use the reverse-video line to switch CG banks.

Just not enough time to play with all the toys, especially If I spend much more writing posts like this one ;-)

carlsson
March 22nd, 2010, 12:44 PM
Is that fellow Philip who posted on this forum as well as the mailing list? :-D

MikeS
March 22nd, 2010, 03:09 PM
Is that fellow Philip who posted on this forum as well as the mailing list? :-D
Yeah, but we haven't heard from him for a while; I assume he's got his PET back by now. You probably followed our ramblings on CBM-hackers.

mrmacca
March 23rd, 2010, 01:20 AM
If you count all models I think you'd be surprised; I know of about 25 just among three or four local friends and I wouldn't be surprised if there were a hundred or more just in the greater Toronto area. After all, any collection of significant vintage computers has to include at least one PET.

Bo Zimmer, Steve Gray, Jim Brain and Anders alone probably have 450 units among them ;-)

Don't forget that many thousands were put into schools, at least in Canada and the US.

Mind you, considering the current theme of this thread maybe instead of "working" we should say "working the last time they were turned on" ;-)

So I've really under estimated how many remain then! I think the PET to be a more popular machine outside the UK. Our biggest seller was the BBC.

I've uploaded some of our bits and bobs here in a new thread. :

http://www.vintage-computer.com/vcforum/showthread.php?19856-Some-Uk-University-Stuff&p=133514#post133514

mrmacca
March 23rd, 2010, 03:26 AM
Back on Topic :

Would a 8224 ETC2716Q-1 or a 8428 ET2716Q-1 Eprom Chip be what I am looking for? As I have found these with 24 pins.

cosam
March 23rd, 2010, 03:38 AM
Would a 8224 ETC2716Q-1 or a 8428 ET2716Q-1 Eprom Chip be what I am looking for? As I have found these with 24 pins.
Either of those should do, assuming they are fast enough. The first four digits are the date code (manufactured in 24th week of '82 and the 28th week of '84 respectively) so they are in fact almost the same part. If you can program one of those with the right image you ought to be in business.

mrmacca
March 23rd, 2010, 04:14 AM
What does the ETC stand for? Someone here has suggested its like TI is Texas Instruments and that ETC could be the old Thomson company? :eek:

mrmacca
March 23rd, 2010, 04:38 AM
I'm gonna go for it, and program this chip....... More later. :)

mrmacca
March 23rd, 2010, 04:57 AM
Hurray. Nearly total success. :)


http://i117.photobucket.com/albums/o65/maccatakker69/pet/DSCF0179.jpg

http://i117.photobucket.com/albums/o65/maccatakker69/pet/DSCF0180.jpg

http://i117.photobucket.com/albums/o65/maccatakker69/pet/DSCF0178.jpg

http://i117.photobucket.com/albums/o65/maccatakker69/pet/DSCF0187.jpg

http://i117.photobucket.com/albums/o65/maccatakker69/pet/DSCF0185.jpg

We used the bin to hex convertor on the characters-1.901447-08.bin (2k) and loaded it up onto the 2617 chip
http://www.keil.com/download/docs/113.asp


The only slight problem is the characters seem to be in capital reverse. Eg. Using the Shift or Shift Lock key produces lower case lettering.
Any ideas folk?

Thank you very much for all your contributions, I am a very happy working commodore pet owner :D

mrmacca
March 23rd, 2010, 05:29 AM
Now we are all sat here not sure whether the shift key was used to lower case the characters rather than upper case as traditional keyboards are

http://freesmileyface.net/smiley/Confused/where-am-i.gif

cosam
March 23rd, 2010, 05:38 AM
Congratulations on the repair - looks good!

And yes, all upper case is the default, shifted is lower case.

carlsson
March 23rd, 2010, 05:51 AM
It seems there exists two different kinds of PET character sets. The early machines defaulted to upper case while the latter machines default to lower case. Thus it is possible you chose the wrong BIN file to program. Hopefully you'll receive my two chips within a week so you can compare function.

mrmacca
March 23rd, 2010, 06:12 AM
Hi Steve, Hi Anders.

I'm really (really) pleased with the repair. Excellent Diagnosis then. Thanks both.

I'm sure this is a later PET and pretty sure it was lower case before. Anders, your right I loaded up the characters-2.901447-8.bin instead of the characters-2.901447-10.bin
I've covered the eproms as someone has advised me here. What do you think guys? Top Job? :)

sjgray
March 23rd, 2010, 06:43 AM
If you count all models I think you'd be surprised; I know of about 25 just among three or four local friends and I wouldn't be surprised if there were a hundred or more just in the greater Toronto area. After all, any collection of significant vintage computers has to include at least one PET.

Bo Zimmer, Steve Gray, Jim Brain and Anders alone probably have 450 units among them ;-)

Don't forget that many thousands were put into schools, at least in Canada and the US.

Mind you, considering the current theme of this thread maybe instead of "working" we should say "working the last time they were turned on" ;-)

Well, I have about 15 if you count my CBM2 models... However a collector friend of mine claims to have at least 100 himself. I think the actual numbers would suprise most people...

Steve

tezza
March 23rd, 2010, 10:09 AM
Congrats on a succesful repair. I just love to see an old Pet spring back to life.

I had an off-the-wall thought when I was reading this thread. We could have an event - a "PET ALIVE" day where on a nominated day (April Fools?), interested PET owners of this forum dragged out any PETs stored more than 3 months and switched them on! The carnage could then be reported baclk.

Now that would be fun! On the other hand maybe it would just be too depressing :)

Whadyaya reckon?

Tez

MikeS
March 23rd, 2010, 10:25 AM
Hi Steve, Hi Anders.

I'm really (really) pleased with the repair. Excellent Diagnosis then. Thanks both.

I'm sure this is a later PET and pretty sure it was lower case before. Anders, your right I loaded up the characters-2.901447-8.bin instead of the characters-2.901447-10.bin
I've covered the eproms as someone has advised me here. What do you think guys? Top Job? :)Tsk, tsk... you shoulda read my post more carefully ;-)

...download the appropriate image (901447-10)...
I wouldn't be too concerned about covering the window but it's a good place to label it.

Congratulations; you're now an official PET expert!

MikeS
March 23rd, 2010, 10:30 AM
Congrats on a succesful repair. I just love to see an old Pet spring back to life.

I had an off-the-wall thought when I was reading this thread. We could have an event - a "PET ALIVE" day where on a nominated day (April Fools?), interested PET owner of this forum dragged out any PETs stored more than 3 months and switched them on! The carnage could then be reported baclk.

Now that would be fun! On the other hand maybe it would just be too depressing :)

Whadyaya reckon?

Tez

I like the idea! Unfortunately I wouldn't be able to participate for three months because this thread persuaded me to fire them up (and the 8032 did indeed have an intermittent monitor cable).

mrmacca
March 23rd, 2010, 11:48 AM
I like the pet alive day idea :) I know it was my own pet but it really was fun getting her fixed.

So how long do people think that eprom will last then? It could have been programmed more times than I've had hot dinners :rolleyes:

dave_m
March 23rd, 2010, 08:56 PM
So how long do people think that eprom will last then? It could have been programmed more times than I've had hot dinners :rolleyes:

There probably is a spec on how many times an EPROM can be erased, I don't remember but it is a large number. Your part, nicely protected from UV rays as it is, should stay programmed for decades.

Last year a retired Rockwell engineer gave me a set of EPROMs for a PET that he programmed in 1983. They worked like a champ.

mrmacca
March 23rd, 2010, 10:24 PM
Ah thats reassuring news.

Looks like the PET may outlive me now then. :D

carlsson
March 23rd, 2010, 11:11 PM
Well, both of your memory chips could fail, or for that matter input and output devices. You may both know how the letters look like, but in the end not being able to produce any coherent writing. :twisted:

tezza
March 24th, 2010, 12:01 AM
Hmm...This "Pet alive" day.

The more I think about it, the more I think it could be fun. I'd like to gauge support. Mike's disqualified himself already but I'm sure a few other regular readers have a PET or two in the cupboard. The reason I suggested 3 months resting qualifiying period is because that's how long my own PET has been dormant.

It could be a fun event, especially if enough people participate and put up pictures of their alive (or now verfied deceased) PETS. The fear I have is there will be so many dead ones, Carlsson's going to run out of spares, Steve will run out of sleep, Dave_m will run out of ideas and Mike will just run, seeing the number of people who now need Pet therapy through this forum.

What's the feeling? If there is broad support I'll put is as an "event" in the Main forum. Many people with dormant PETs don't necessarily read this Commodore forum religiously.

(Note: "Broad support" in this context means that most of the regular PET experts are supportive...cause they are likely to be the medics dealing with at least some of the casualties! I don't want to give you guys more work than you want.).

I'm not sure how many takers there will be but...no harm in flying the kite. I'm picking a lot will be too afraid to switch their's on.

Tez

carlsson
March 24th, 2010, 01:48 AM
All my PETs are in the basement and it takes a bit of effort to haul one into the apartment. But sure, I can join. Even better if we have some task to perform. Those of us who own IEEE floppy drives and one of those cbmlink compatible cables could try some disk transfers, report success and how we went ahead: PC64, C2N232, PRLINK, X-cable and so on.

By the way, did you see the Christmas card I sent to some of my friends?
http://www.cbm.sfks.se/pics/godjul-final.jpg

mrmacca
March 24th, 2010, 06:44 AM
Cool That Anders. :cool:

Another of your friends and some one you've help Andrés Fachat asked me if he could use my pictures for his website incase some one else has the same fault.

I uploaded the best ones here :

Clicky (http://www.fcet.staffs.ac.uk/atm2/pet/)

You have to click the thumbnails for the bigger pics.

I think I now need to invest in a floppy system like yours in the picture. :rolleyes:

carlsson
March 24th, 2010, 07:14 AM
Before our North American friends tell you the 8250LP is a very rare floppy drive, I'd like to mention it seems quite a bit more common in Europe. A little bit lighter than a full height 8250, but not quite as stackable. If you insist, regular 3040, 4040, 8050 and 8250 drives should probably be possible to find within the UK for not too much money.

dave_m
March 24th, 2010, 07:53 AM
It could be a fun event, especially if enough people participate and put up pictures of their alive (or now verfied deceased) PETS. The fear I have is there will be so many dead ones, Carlsson's going to run out of spares, Steve will run out of sleep, Dave_m will run out of ideas and Mike will just run, seeing the number of people who now need Pet therapy through this forum.

Tez

Tez, count me in.
-Dave

dave_m
March 24th, 2010, 07:56 AM
Before our North American friends tell you the 8250LP is a very rare floppy drive...

Anders,
Rare? I'll say. I've never seen one. Thanks for the picture. I like the slim design. My 2040 is quite the boat anchor.
-Dave

cosam
March 24th, 2010, 08:02 AM
For some of us, every day is PET alive day ;-) Bring it on!

I'd be able to dig my 2001 out and it's certainly been dormant for more than 3 months. Maybe we should all run the same program and post photos of the results as proof that our machines are alive.

carlsson
March 24th, 2010, 08:14 AM
If anyone makes a port of Folding@Home, we could let our PETs crunch partial packages and shift the results inbetween us in order to get one complete package done. :-D

Dave: In the past 4-5 years, I've come across some 20 units of the 8250LP. All were rescued, but I only took care of a handful myself. Perhaps my distribution was unusually uneven, but if I didn't know better I would think at least 1/4 or even 1/3 of all IEEE drives are LP's. Not sure why so many ended up in Europe and so few in the USA. Perhaps the slight delay of the IBM PC (not here until 1983 or so) gave room both for Victor/Sirius systems as well as letting Commodore run their PET and CBM-II lines a little longer than they would have market shares for overseas. Well, this is highly speculative writing.

tezza
March 24th, 2010, 10:30 AM
Re: Pet Alive!

Thanks guys. I think this could be fun event. I got to rush off now but I'll think more on this today. I'm starting to think now this should be less of a just a "switch it on and see what happens"-event (although that could be part of it) and more a celebration of the PET. People could supply a photograph of our "groomed" PET doing something. A chance for people to drag their PETs out for a walk.

I'm thinking the event could be over a weekend, maybe in a week or two.

Anyway, more later...

Tez

MikeS
March 24th, 2010, 10:52 AM
Re: Pet Alive!

Thanks guys. I think this could be fun event. I got to rush off now but I'll think more on this today. I'm starting to think now this should be less of a just a "switch it on and see what happens"-event (although that could be part of it) and more a celebration of the PET. People could supply a photograph of our "groomed" PET doing something. A chance for people to drag their PETs out for a walk.

I'm thinking the event could be over a weekend, maybe in a week or two.

Anyway, more later...

TezWell, I guess I could put little casters on the PETs, or at least make a little platform with casters for them; a leash should be no problem and I've got lots of UPS power to run them off while we're out for our walkies...

MikeS
March 24th, 2010, 11:14 AM
If anyone makes a port of Folding@Home, we could let our PETs crunch partial packages and shift the results inbetween us in order to get one complete package done. :-D

Dave: In the past 4-5 years, I've come across some 20 units of the 8250LP. All were rescued, but I only took care of a handful myself. Perhaps my distribution was unusually uneven, but if I didn't know better I would think at least 1/4 or even 1/3 of all IEEE drives are LP's. Not sure why so many ended up in Europe and so few in the USA. Perhaps the slight delay of the IBM PC (not here until 1983 or so) gave room both for Victor/Sirius systems as well as letting Commodore run their PET and CBM-II lines a little longer than they would have market shares for overseas. Well, this is highly speculative writing.I've always wondered whether the LP drives would fit into my 8032; it's one of the tall early models with cutouts and mounting pillars behind a snap-in faceplate obviously intended for a pair of integrated floppies, but the height & mounting pillars don't match a standard 5 1/4 drive.

Faceplate removed to show cutouts; note how it's taller than the 4032 beside it (same universal board inside though).
3370(Click for larger pic)

MikeS
March 24th, 2010, 11:22 AM
All my PETs are in the basement and it takes a bit of effort to haul one into the apartment. But sure, I can join. Even better if we have some task to perform. Those of us who own IEEE floppy drives and one of those cbmlink compatible cables could try some disk transfers, report success and how we went ahead: PC64, C2N232, PRLINK, X-cable and so on.

By the way, did you see the Christmas card I sent to some of my friends?
http://www.cbm.sfks.se/pics/godjul-final.jpgYeah, I'd seen that card before; beautiful!
No power in the basement? No UPS to take down with you?

carlsson
March 24th, 2010, 02:45 PM
Well, an outlet in the corridor but it means I have to haul the PET out from my storage space anyway.

As a matter of fact I have a couple of loose Matsushita mechanisms pulled from 8250LP drives. Those are in highly unknown condition, and I don't feel like swapping working mechs for possibly broken ones in case it ends in destroying circuitry. I already killed one or two LP drives by swapping boards and chips between identical units, on which one unit must've had really nasty chips that I discovered too late.

tezza
March 25th, 2010, 12:51 AM
Guys,

I've sent a PM to you all with more ideas about the Pet Alive! day. I thought maybe better to do it there, rather than hijack this thread.

mrmacca
March 25th, 2010, 01:26 AM
I've replied in PM but I don't mind people pinching my thread.. (Now shes working) :satisfie:

Nama
April 17th, 2010, 01:34 PM
...Actually very late!!!

I'm the 'Philip' mentioned earlier in the thread. The one who made the JPN character ROMs. MikeS, nice to see you're still using them. My own machine is still not fixed yet :(

Anyway, I thought I'd mention that one way you could have initially tested the character ROM is by systematically shorting between the outputs of the ROM and watching the characters change on screen (always fun). Eventually the outputs that were stuck would be shorted to another non stuck output and the lines would have disappeared being replaced with something else. I've done this simple test many times in the past and it's helped me numerous times to find, and fix similar issues on various hardware.

Phil

MikeS
April 17th, 2010, 04:38 PM
...Actually very late!!!

I'm the 'Philip' mentioned earlier in the thread. The one who made the JPN character ROMs. MikeS, nice to see you're still using them. My own machine is still not fixed yet :(

Anyway, I thought I'd mention that one way you could have initially tested the character ROM is by systematically shorting between the outputs of the ROM and watching the characters change on screen (always fun). Eventually the outputs that were stuck would be shorted to another non stuck output and the lines would have disappeared being replaced with something else. I've done this simple test many times in the past and it's helped me numerous times to find, and fix similar issues on various hardware.

PhilWell, hello there Philip; fancy meeting you here! Guess you have to be careful what you say here; ya never know who's reading...

That's a good tip, but I usually use a low-value (~56 Ohms) resistor when connecting outputs together just in case, and especially when grounding them or connecting to Vcc.

Haven't gotten around to trying to use Japanese, graphics and 'normal' upper and lower case symbols on the same screen yet; looks easy on an 80/4032 but I'm probably overlooking something crucial; a bit more challenging on a non-controller PET though by the looks of it.

Sorry to hear you don't have your beloved PET back yet; I gather Ethan's been very busy since at work he has to fill in for someone, and your PETs turned out to have some other more subtle problems than just PS and ROM trouble as was originally thought. But I'm sure you'll see them again soon; he hasn't sold them or run off to Mexico with them AFAIK...

Nama
April 17th, 2010, 04:58 PM
Yeah, Ethan has been very helpful. It's unfortunate that he's been tied up so much with other more important things (i.e. making a living). However I'm hoping to get the boards back sooner rather than later. The chassis has been sitting on my desk for the last 6 months looking quite lonely indeed.

The last email I got from Ethan says that he now has both boards powering up on screen, One still has a loading/saving issue (although now partially fixed), and the other has vertical lines running down the length of the screen (not to dissimilar to the original issue on this thread, but by the sounds of it they are not character based errors). This is what Ethan had to say about this latter board:

"it has stuck bus bits - D1-D6
tied together. It seems likely that it's something with 8-bits
through it, not merely 4, so it's more likely to be a PIA, CIA, or a
ROM rather than a 244 buffer or the SRAM. I did test the SRAM in my
own board - looks like I've found a few that have bad bits. This is
not at all uncommon with Static PETs."

...as for the board with the load/save issue, Ethan has this to say about it:

"As for the tape/disk issue, it looks like a bad 6522. I swapped out a
65C22 for your 6522. Loading from the disk doesn't lock up anymore -
it gets "DEVICE NOT FOUND". The tape drive responds to "PLAY" and
does allow me to hit RUN/STOP to break back immediate mode. The tape
doesn't spin, from either port. That could be on of several parts,
but the controls are on different I/O ports, so it's probably not
that, especially since one is controlled by the VIA I replaced."

So indeed, some really good progress made by Ethan. I just hope he can figure it all out.

Phil

Nama
April 17th, 2010, 05:02 PM
Oh...for the PET alive event I will post some pictures showing this unusual Japanese PET 2001 with Japanese chicklet keyboard. I've never seen or heard mention of a Japanese PET 2001 before. So it was just by luck I happened upon this one on Japan yahoo auction.

MikeS
April 17th, 2010, 08:18 PM
Oh...for the PET alive event I will post some pictures showing this unusual Japanese PET 2001 with Japanese chicklet keyboard. I've never seen or heard mention of a Japanese PET 2001 before. So it was just by luck I happened upon this one on Japan yahoo auction.Well, then I guess I'll have to dig out my Japanese 4032 to keep yours company; they must be lonely...

As to your PETs, unless they're intermittent those problems don't sound too difficult to find/solve (easy for me to say ;-) ), so it shouldn't be much longer...

Nama
April 18th, 2010, 03:53 AM
Yes, please do. I still have the pics of your Japanese keyboard you sent me for reference when I was making the Japanese ROMs.