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EagleTG
October 15th, 2016, 10:58 AM
I was working with dmemphis (http://www.vcfed.org/forum/member.php?33461-dmemphis) today in an attempt to build adapters (and power circuitry) to read the 2716 EPROM from a SuperBrain. Additionally, we re-burned some "backups" to 28C16 EEPROMs and built the associated adapter to use these in a SuperBrain.

The ROMs we read seem to be previously unarchived. I have uploaded them to my website, but we intend to get these up on BitSavers, too.

Here are the links:
http://retro.togeo.com/files/SuperBrain%204_003%20VC8001.Bin
This was from a SuperBrain and was labeled as 4.003 (and displays that version upon boot)

http://retro.togeo.com/files/SuperBrain%20QD%203_05.Bin
This was from a SuperBrain QD and was most boringly just factory labeled with the "Intertec" logo and proved to be version 3.05

For comparison, the ROM image that is up on BitSavers at http://www.bitsavers.org/pdf/intertec/firmware/SuperBrain.bin is version 3.1 according to the boot prompt. We are not sure if this a QD ROM or not.

In another thread, user snuci (http://www.vcfed.org/forum/member.php?27772-snuci) posted a ROM that was very similar to our v4.003 above, differing by 3 bytes as-follows:

Comparing files SuperBrain 4_003 VC8001.Bin and SUPERBRAIN_TMS2716C.BIN
000003F7: 55 56
000003F8: 0C 0A
000003F9: 08 07

Thanks!

snuci
October 15th, 2016, 11:13 AM
Just curious, did you guys get the SuperBrain running?

dmemphis
October 15th, 2016, 01:52 PM
In short, yes we did have the SB functioning.

I have two, one regular and one QD.
The regular one, which I bought as a parts machine actually works, I found recently.
However, it is in rough shape and though the boot drive worked once I did not want to use the drives again
without refurbishing them.
My SB QD is currently disassembled so we could not use it but we could use its drives which I
refurbished last year.

We proceeded take the known ROM images (from bitsavers, from snuci, and those we read from
my two SBs) and successfully program them to 2816 EEPROMs.
Then we tried all the EEPROMs in the working SB using an adapter socket EagleTG fashioned to run 2816 EEPROMs in the problematic TMS2716 sockets of the SBs. Results:

Snuci's 4.003 VA7001 image: WORKED. Seemed to work just like the 4.003 VC8001 EPROM that came with the SB.
(As EagleTG noted, there are three bytes different between them)
Image from my SB QD, internally identified as 3.05: DID NOT WORK. Printed a prompt then hung.
BitSaver's image: internally identifed as 3.1: DID NOT WORK. Printed a prompt then hung.

Here is a successful bootup from floppy using the Snuci ROM:
Before the drive door was closed: 33853
Drive door closed: 33848
These are the screens from the versions that did not work:
BitSaver Image: 33849
My QD EPROM: 33850

Summary:
All the 2816 EEPROMS made from available images appear to be functional PROM media in the SB sockets.
Snuci's ROM appears to function the same as the EPROM that came with the SB.
My QD 3-.5 and the BitSaver's 3.1 EPROM image seem to function equivalently bad.
Perhaps the BitSaver is in fact a QD ROM image, and a bit later revision than mine.
Since my QD ROM did not function in the regular SB, ROMS between these two types are likely not interchangeable.

This was a significant push forward from where we were a few days ago. We did all this without destroying an
existing original TMS2716 ROM and now have images and 2817 replacements for everything. We know what
ROMs work in a standard SuperBrain. Soon I will be swapping some parts to my QD from the regular model, and then can try the 3.05 and 3.1 EEPROMs in the QD.

Next we have to try to locate some of the enhancement ROMs that were offered :O

snuci
October 15th, 2016, 02:28 PM
Glad it helped, dmemphis!

I was able to get one of my two SuperBrains up but didn't have a good boot disk. Still working on that. I did have a successful boot and it turned out that both of my ROMs were good and identical (I had originally seen all 00s for one). My second SB powered up with flickering floppy drive lights for about 10 seconds, then the "magic smoke" started pouring out :( I need to find a schematic (haven't had a chance to look around yet) but I originally saw some blackness around three pins on one of the 4116 memory chips but when I went to take it out, it looks like a diode (?) blew as it crumbled when I got close to it.

I'll have to find out what the value of that is as it is unreadable.

33855

ldkraemer
October 15th, 2016, 02:59 PM
snuci,
From the photo you attached it appears that device is connected to Pin 1 of the 4116 Ram IC.
4116
Pin 1 Vbb -5 VDC
Pin 8 Vdd +12 VDC
Pin 9 Vcc +5 VDC
Pin 16 Vss GND

My guess is that it is a Capacitor as the Intertec Schematic shows 6 Bypass Caps on the first row of RAM IC's,
5 bypass caps on the next three rows of RAM IC's, and there are also 5 larger caps at RAM IC's
Z7, Z15, Z23, and Z31 (Z31 has one below it also). The unmarked decoupling caps are noted to be 0.1uF caps.
There are no diodes shown on the layout drawing around the area of the RAM IC's.
The print is unclear as to the value of the larger caps over the RAM chips. The best thing would be to unsolder
another one close to the blown one and measure it's value.

Larry

snuci
October 15th, 2016, 03:09 PM
Your right. I was looking over the schematic on Bitsavers and it looks like it might be 10uF but it is blurry. At least I know the blurry markings are the same for each cap on that vertical row so I'll what you suggest.

By the way, I am not complaining. Blurry is better than nothing. I'm happy that the schematic is even there.

Thanks for the advise. I appreciate it.

dmemphis
October 15th, 2016, 07:18 PM
Finally after two years of it sitting around, and a year ago since I gave up on fixing the power supply,
I have the Superbrain QD back together with pieces from the doner Superbrain.
So I was able to test the 3.1 ROM image. As fate would have it, when I did the first power on
with the original 3.05 ROM, I got NOTHIN. Oh No. It behaved like the ROM was dead.
But fate was also kind: I put in the 3.1 Atmel 2817 EEPROM in the adapter, and it sprang to LIFE.
Wouldn't you know my ROM would fail now? Bad handling? On the edge? We'll never know, but
at least we have the image file and we can make copies if we think we need it.
I neglected to make a 2816 EEPROM of the 3.05 image and EageTB has the burner.
So figuring out if that image is good (it probably is, it looked good but all bets are off) will have to wait.
But the 3.1 Image from bitsavers seems to be fine.
Here's the machine finally back in its glory:
33863

dmemphis
October 16th, 2016, 10:28 AM
33873

dmemphis
October 16th, 2016, 10:33 AM
Our adapter for reading a TMS2716 ROM in a more modern ROM programmer.
5V is coverted to + & - 12v, then -12v is converted to -5v.
33874
(Ground of regulator wasn't solder well... that's fixed now :)

dmemphis
October 16th, 2016, 02:28 PM
Last night I overlooked a 2816 containing the image from my original QD rom, 3.05 VC8001.
Good news, it works. So though my original QD ROM is non functional now, I know the ROM image is good.
It appears to operate the same as the bitsaver 3.1 version in the QD.

Josh Bensadon
October 16th, 2016, 06:08 PM
Hi,

I fixed a SB a couple of years ago, gave it back. But I did make a copy of the ROM if you're interested?

Cheers,
Josh Bensadon

dmemphis
October 16th, 2016, 08:19 PM
Hi Josh:

Yes, that would be great!

alan8086
October 19th, 2016, 07:14 AM
Hi - I just wanted to post a thankyou, for your efforts. I have a Superbrain QD - started a thread here:

http://www.vcfed.org/forum/showthread.php?54295-Intertec-Superbrain-Call-For-Help-10-Years-On

- I'm a way off diagnosing its problems but its great to know I now have access to the ROM code should I need it!

Thankyou again!

JonB
April 11th, 2017, 08:27 AM
So I take it that the TMS part needs -5v to read in a modern programmer, but most don't provide this voltage.

What ROM do you select in the programmer's software to read a TMS2716C? I presume 2816.

I drew up a schematic for the programmer adapter. The 5 pin header connects to the +5v to +-12v board.

37748

I also drew up a schematic for the Superbrain 2816 adapter that you fit to the motherboard so that the SB can read a 2816.

37749

Could you check them to see if they are correct, please?

Thanks
JonB

JonB
April 12th, 2017, 08:25 AM
This ROM adapter might be made to fit under the top cover of the Superbrain:

37771

It all depends on the pins used to solder in the "legs" of the thing. The board needs to be as close to the Superbrain's motherboard as possible. I suppose it would be possible to remove the ROM socket from the SB motherboard and solder this directly to it - that should give clearance, at the cost of not being able to use a TMS ROM again. Not an issue in my opinion, because you can always dump the TMS ROM and program a nice shiny new 2816 EEPROM with the contents.

If you want to have a go, you can order them from OSH Park (https://www.oshpark.com/shared_projects/KtXDGAsf) in sets of three. I've got one set of 3 on order (minimum quantity) so if any UK Superbrain owners fancy a card, let me know.

** DISCLAIMER **
Untested as of this post, so order at your own risk!

JonB
April 13th, 2017, 06:46 AM
Here's my implementation of the TMS2716C reader for modern programmers.

37788

That's the Superbrain ACT HDD ROM sitting in the socket. Guess what I found when I attempted to read it in my TOP853 programmer?

37789

Yep, looks like bit rot hasn't got it yet. And in this ROM we can see the following strings:


"3.1 INSERT DISKETTE INTO DRIVE ", and (this is the money shot...)
"PRESS 'F' TO BOOT FROM FLOPPY, ANY OTHER KEY TO BOOT FROM HARD DISK"


The content might not be complete, but there it is.

alan8086
April 13th, 2017, 02:48 PM
That's nice to see! There's hope yet! Have you ever been in touch with that guy in the Netherlands who worked during the 1980's customising Superbrains with non OEM HDs and controllers, forget his name - seemed very knowledgeable if slightly reticent.

alan8086
April 13th, 2017, 02:55 PM
I'm guessing the answer will be yes as a google search led me back here to a long post and a guy named Roland Huissman. Seemed quite the expert, wonder what he'd have to say about your non standard HD setup?

EagleTG
April 18th, 2017, 05:21 PM
Very nice JonB!

What is that adapter board (the PCB itself?)... Looks like something cool to know about.

Sorry for my delay in reply, but it looks like you have everything sorted out very nicely. Your schematics are very small thumbnails. Any chance to get a slightly higher resolution copy? Might not matter as it seems like you've confirmed they work.

Are you planning on any runs of the 2816 adapters? If so I might be interested.

Also, I have to apologize but I really don't remember what EPROM we used in the reader config to read the 2716. I would guess it was either 2516 or 2816. I remember we looked up pinouts of similar size and vintage EPROMs. I guess that you don't need that info, as it appears you read yours already. :)

JonB
April 19th, 2017, 12:22 AM
Hi Todd

The board is a Z80 shim I designed for the uIDE general purpose Z-80 IDE adapter card, hacked about a bit. Read all about it here:

http://www.cpcwiki.eu/index.php/UIDE_Universal_IDE_adapter_cards_for_Z-80_computers

..and I will offer these cards to Superbrain owners with suitable drivers, once I have got mine running. Yes, you too can have a whopping 128MB of HDD space available to your Superbrain, maybe, for peanuts. Better days are at hand for Superbrain owners...

To the TMS27C16 adapters, then. I designed a proper PCB for both host and programmer adapters and sent them to OSH Park for fabrication. There's only three of each at this stage and they are (mostly) spoken for, but it's easy enough to get more. I would need to make sure they work properly first.. and fit; the host adapter doesn't really have enough space inside the Superbrain, unless the original socket is fully removed and the adapter is soldered into its position, but even then..

You're correct in that I have read my EPROM and it is OK (this is the special ACT HDD ROM). I posted a copy of the dump earlier on. To do this I set the programmer to a 2816 EEPROM and read. Worked first time, with the "red board" adapter (prototype). Since then I hacked up a host adapter out of pin header strips and jump wire, programmed a 2816, shoved it in the Brain's EPROM socket and attempted boot. Naturally, it didn't work! Not becasue the ROM is bad, or the adapter, but because the Brain is sick.

I have a Z80-ICE here and I can see that memory access is not working properly. I suspect it is something to do with the ROM paging logic. Do you know anything about it? I've been working with ldkraemer on this, he has been looking out for useful info and came up with this stuff from comp.os.com:

37899

In it a chap called Warren W. Gay muses about the EPROM of the Superbrain and how it works with the first and second CPU. I've not read it all, but I am very keen to work out how the memory paging is triggered (probably via I/O ports), then I can check mine is OK. It's frustrating, because all this has been done before, but the information seems to have been lost.

If you have any information on this, please let me know as I am at a bit of a standstill. The schematic confuses me!

Cheers
JonB

EagleTG
April 19th, 2017, 05:04 PM
That shim is awesome. I'll read more on that later.

Awesome on the adapters, I'll be keeping an eye on this thread. :)

I've also noticed the tolerance issues with this computer, so definitely interested to see the fitment of your adapter once it's done. :)

Sadly, I don't know anything about the ROM paging logic at this point. Thanks for the link to the Lobotomies. Good name, too. Hahha

Also, I wanted to cross-post to the other thread where we talked about ROM dumping on the SuperBrain... I posted a link to THIS thread, but not the other way around: http://www.vcfed.org/forum/showthread.php?54295-Intertec-Superbrain-Call-For-Help-10-Years-On/

See ya.

JonB
April 20th, 2017, 01:49 AM
Thanks Todd.

It's quite simple, really, but incredibly useful, sometimes. I'll post pictures of the ROM adapters once I receive them and build one of each.

Meanwhile, I contacted the author of the "Superbrain Lobotomies" posts on comp.os.cpm and he has kindly put his ROM disassembly onto github here: https://github.com/ve3wwg/superbrain_lobotomies

..in case anyone out there can use the information.

JonB
May 4th, 2017, 02:56 AM
Superbrain ROM adapter board.. This is the adapter that allows use of a 2816 EEPROM on the Superbrain motherboard without modifying any tracks on the Superbrain. It's based on the reader design presented by EagleTG and dmemphis on this thread.

The bare board.
38239

Top view, assembled.
38240

Bottom view, assembled.
38241

In situ with CPU2 on the right.
38242

With a 2816 fitted.
38243

This rig is not going to fit as-is with the case closed. For that, I think you would need to remove the ROM socket from the motherboard and solder the adapter directly (in the picture it is plugged into the socket). You may also need to solder the 2816 directly to the adapter to save a few more millimetres. I've done a quick trial and it may be OK without removing the socket, but it would need some finessing in the assembly stage.

JonB
May 4th, 2017, 03:02 AM
TMS27C16 reader adapter board.

38244

P3 has the tiny voltage converter module soldered to it. U1 is the 7905 5-12v regulator. As the current requirement is so low, I think we can get away with a smaller device such as a 79L05 (which I will be testing). I'm waiting for some of these modules to arrive from China before attempting to build one - don't fancy desoldering it from my prototype (the red board).

Once built, you would use this to retrieve the content of your Superbrain ROM using a modern programmer, and setting the programmer for a 2816 EEPROM.

There are only three of each type of board at the moment and I think they are all promised out.

dmemphis
May 4th, 2017, 04:03 AM
Nice work!
My double socket plus 2816 IC fits under the case with only a slight impingement.
Your adapter should even be less, though it might touch.
Its a feature, it holds it in place!

JonB
January 8th, 2019, 11:22 PM
I've just acquired a SB II board which I am attempting to nurse back to health. It has a boot ROM labelled 4.2, which appears to be working. Will upload a dump presently.

JonB
January 17th, 2019, 04:59 AM
Turns out I already had a copy of this ROM. It came from zippysticks' SB II.

JonB
February 4th, 2019, 07:43 AM
Here's the UK spec (50Hz) Superbrain II 4.2 ROM