PDA

View Full Version : Commodore 64 Help



reputodiversus
February 13th, 2007, 12:44 PM
Hello, i recently purchased a Commodore 64 off of Craigslist.com. The unit appeared to be in good shape and had all the parts but the seller never mentioned if it worked or not. The unit powers on and has (what i believe is a video RCA connection?) but i cannot display video. The only thing the unit is missing is a manual so perhaps i am doing something wrong. Any help would be greatly appreciated, i'd hate to find out that i dropped 30 bucks on a dud :confused:

PhotoJim
February 13th, 2007, 01:33 PM
The video isn't RCA, unfortunately. You need to buy a video cable to plug into the 8-pin DIN port on the back of the machine to provide you with a video signal, or find an RCA-to-coax cable to hook up the RCA jack output to a TV input jack.

reputodiversus
February 13th, 2007, 01:58 PM
where would i go about finding these, you think radio shack would have them?

reputodiversus
February 13th, 2007, 02:01 PM
by RCA-to-coax do you mean an RF modulator? if so i could get one of those anywhere.

ahm
February 13th, 2007, 03:07 PM
No, you don't need an RF modulator.
The signal at the RCA jack of the C64 is already RF modulated.
If you run a cable from it to your TV's antenna jack and tune the TV to channel 3 or 4, you should get a picture.
(I use a cable with RCA male on both ends, and an adapter: "F" male to RCA female)

One of the other jacks is for monitor video, but that's the one that needs a special cable.
Maybe this will help:
http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c64/c64-r1.chips.gif

Andy

reputodiversus
February 13th, 2007, 08:13 PM
ok so i went to radio shack and bought the RCA-to-Coax. It works, is there suppost to be sound, or how can i test it. i dont have any cart's or any thing so is there anything on the c64 stock to be able to mess around with?

ahm
February 13th, 2007, 08:52 PM
http://www.lemon64.com/manual/
There's a sample sound program in Chapter 8.

carlsson
February 13th, 2007, 11:29 PM
Quickest way to test for sound:

POKE 54296,15:POKE 54278,240:POKE 54273,100:POKE 54276,33
(max volume, full sustain ADSR, medium pitched note, sawtooth waveform)

Turn it off with POKE 54296,0 or hit RUN/STOP + RESTORE.

The manual example is good too, but a bit long to type in just to test if the sound chip is OK or not.

Vlad
February 14th, 2007, 06:57 PM
Moved to Commodore....

-VK

reputodiversus
February 14th, 2007, 08:16 PM
ok so i tested these things but they didnt work, i dunno if that means its faulty or if im not using the proper connection, if i have the rca-to-coax should that be producing noise or do i have to use another cable separately?

NathanAllan
February 14th, 2007, 08:26 PM
How about this,

go into basic (you'll be there with no bootdisk after you start up):

10 BEEP
20 END
RUN

Will this work? Works on the Vic 20.

Nathan

reputodiversus
February 14th, 2007, 08:30 PM
well is that gonna work even if i might not have the proper audio connection or will that come from inside the machine itself

reputodiversus
February 14th, 2007, 08:35 PM
when i type in

10 BEEP
20 END
RUN

(then push return)
i get

?SYNTAX ERROR IN 10

NathanAllan
February 14th, 2007, 08:37 PM
It should come from the TV speaker if it's hooked up through that RF connector.

reputodiversus
February 14th, 2007, 08:43 PM
im using that RCA to coax converter i scored from radio shack, its running through the cable in on an old tv. but that line you told me to run didnt work, maybe its the cord? worst case no sound i guess which is a major bummer cuz i bought it to run prophet 64...:confused:

NathanAllan
February 14th, 2007, 08:58 PM
Okay, I'm forgetting something. All the books I have on BASIC say that BEEP is a basic command that works. I've used it on every basic-speaker I have. googled it and found the same thing, lots of programs with BEEP in them and that makes it BEEP. Stil looking...

NathanAllan
February 14th, 2007, 09:00 PM
How about just BEEP and then <return>?

I'll keep working on it. Back after a while.

reputodiversus
February 14th, 2007, 09:02 PM
when i type beep i get a syntax error again

billdeg
February 15th, 2007, 03:42 AM
start looking for a 1701/1702/1802, etc. monitor!

carlsson
February 15th, 2007, 03:51 AM
No. There is no such keyword as "BEEP" in Commodore Basic V2. Perhaps on the Plus/4 or C128, but I doubt it. On the VIC and C64, there is not a single keyword for handling graphics or sound, just POKE and PRINT all the way.

reputodiversus: Do you get a proper picture, perhaps even in colour with a flashing cursor that lets you type in stuff, only that you can't hear any sound? Using the RF connection, you should get sound from your TV set. Perhaps it has a bad SID chip or the built-in RF modulator.

reputodiversus
February 15th, 2007, 04:11 AM
i get video fine, just no sound. and im not using an rf modulator im using the rca-to-coax adapter. would it benefit me to try and get that DIN to RCA off ebay or something?

carlsson
February 15th, 2007, 06:09 AM
The C64 has a RF modulator built into the box. The RCA connector actually carries a RF signal, that is why it is possible to connect to your antenna input if I understand correctly.

To make matters worse, as late as last week I learned that the video and sound signals are routed through the built-in RF modulator both for the RF output and the video outputs on the DIN connector. I'm no whiz in electronics, but I believe that if - perhaps unlikely - the RF modulator starts to malfunction, it will affect all video and sound output no matter which method of connection you choose. Admittingly, I have never heard that the RF modulator should fail, but I'm not certain it is forever failsafe.

If you try a DIN solution, audio output is carried on pin #3. A fully configured cable uses a 8-pin DIN and has three RCA jacks for separate video + sound. Another common cable uses a 5-pin DIN and only two jacks, giving composite video + sound. The information above about which pin carries audio was meant if you make your own cable, perhaps for connecting it to an amplifier in your home studio since you mentioned you're planning to use it with Prophet 64 for audio processing.

NathanAllan
February 15th, 2007, 06:43 AM
No. There is no such keyword as "BEEP" in Commodore Basic V2. Perhaps on the Plus/4 or C128, but I doubt it. On the VIC and C64, there is not a single keyword for handling graphics or sound, just POKE and PRINT all the way.

DOH! I found my Basic handbook and compared with the Vic 20 book and you're right. My mistake reputodiversus. Faulty memory. Mine, not the machine's.

carlsson
February 16th, 2007, 04:01 AM
Is that David A. Lien's book? I have that one too, but depending on which revision you have it may only cover the earliest Basic computers (c:a 1982). Also it mainly covers US mini and micro computers, which is not a problem in this case as Commodore was a US brand unlike e.g. Sinclair, Amstrad, Acorn, Oric and so on in the Europe and of course all Japanese MSX based and other brands.

ahm
February 16th, 2007, 04:47 AM
No one seems to have asked the obvious question:
Is the volume turned up on your TV?

NathanAllan
February 16th, 2007, 04:55 AM
Is that David A. Lien's book? I have that one too, but depending on which revision you have it may only cover the earliest Basic computers (c:a 1982).

That's the one, I got it for $0.10. Can't remember what revision it is, (not handy now) but it has Atari 800 specifics in it(not ST). Love it! I want to find more of them.


No one seems to have asked the obvious question:
Is the volume turned up on your TV?

DOH!

reputodiversus
February 16th, 2007, 06:02 AM
yeah the volume is turned all the way up, im not THAT retarded...

ahm
February 16th, 2007, 06:12 AM
Neither was the person who spent an hour on the phone insisting his monitor was broken, until I asked him to adjust his brightness.

NathanAllan
February 16th, 2007, 07:56 AM
It took me an hour to figure ou that my Vic wasn't showing a clear picture 'cause of the V-hold. I just say "duh me" and move on.

carlsson
February 16th, 2007, 09:06 AM
it has Atari 800 specifics in it
Yep. It specifically mentions Atari 400/800, TRS-80, Tektronix, Acorn Atom (UK one!) and a bit about generic disk operating systems. I've had a bit of use of it, in particular when converting listings featuring ARCSIN and other bizarre stuff.

reputodiversus
February 16th, 2007, 10:53 AM
well i made sure i turned the volume up on the TV and i dont see a volume knob on the machine so i dunno, any more tests i can run before i just say 'screw it the sound dont work'?

reputodiversus
February 16th, 2007, 10:59 AM
Quickest way to test for sound:

POKE 54296,15:POKE 54278,240:POKE 54273,100:POKE 54276,33
(max volume, full sustain ADSR, medium pitched note, sawtooth waveform)

Turn it off with POKE 54296,0 or hit RUN/STOP + RESTORE.

The manual example is good too, but a bit long to type in just to test if the sound chip is OK or not.

ok perhaps a breakthrough? i did this again running the full line (previously i had run the POKE's as single commands) and when i key it all in i get a semi high pitched note thats constant (dunno if that is what im suppost to get) and when i keyed in the command to stop it it stopped. So it produced SOME noise, just not sure if its the right noise?

NathanAllan
February 16th, 2007, 12:12 PM
Just for testing purposes, why not buy a single game cart to see if it'll make sound that way?

Worked for me on the Vic.

Kinda related, how much would you pay for a Oki 180 line printer? I have run across one, and it has the C= plug on the back of it as well as centronics(for both atari and C= maybe??)

Druid6900
February 16th, 2007, 07:51 PM
I have a mint 1802, even have the ower's manual, (might even have a 8 pin DIN to 3 RCA cable around) that I would hate to part with, but, if you can't find one on e-bay (they don't show up too often) or anyplace, and you REALLY want one, let me know.

wiskow
February 17th, 2007, 06:56 AM
i get video fine, just no sound. and im not using an rf modulator im using the rca-to-coax adapter. would it benefit me to try and get that DIN to RCA off ebay or something?

The only benefit you'd see to getting a monitor cable as opposed to the cable you're using now to connect to your TV would be much improved video quality. I don't think you'll notice much improvement in audio quality at all.

Which model of C64 are you using? Is it the older brownish-grey C64, or the newer white "slim" C64c? If it's the older one, and everything is working fine except for the audio, then you probably just need to swap out the SID chip. In this older model, the SID chip is at position U18, and is labeled 906112-01 (6581). If you have the newer C64c, then it *may* be a bad SID chip. In this model, the SID chip is located at position U9, and is either 318013-01 (8580) or 906112-01 (6581). Another possible problem if you have a C64c, and I've personally encountered this problem on two C64c's, it could be a blown fuse inside the computer. If the 1.5 amp fuse is blown, the computer will seem to work fine, but there will be no sound, and the user port and cassette port will not function correctly. If you're not using the user port or cassette ports, then you may not have noticed that they're not working.

Hope this helps! :-)

-Andrew
___________________________________
Cottonwood BBS
+1 (951) 242-3593
Open 24/7 at 300/1200/2400 baud
http://hometown.aol.com/cottonwoodbbs (http://hometown.aol.com/cottonwoodbbs)

wiskow
February 17th, 2007, 07:01 AM
I have a mint 1802, even have the ower's manual, (might even have a 8 pin DIN to 3 RCA cable around) that I would hate to part with, but, if you can't find one on e-bay (they don't show up too often) or anyplace, and you REALLY want one, let me know.

You can get a Commodore monitor at the 64 & More Store ( http://www.64andmore.com/ ). They're reasonably priced, FULLY tested, include all required cables, well-packaged, and shipped quickly! I just bought a 1902a monitor from there for my C128, so I speak from experience... :-)

-Andrew
___________________________________
Cottonwood BBS
+1 (951) 242-3593
Open 24/7 at 300/1200/2400 baud
http://hometown.aol.com/cottonwoodbbs (http://hometown.aol.com/cottonwoodbbs)

carlsson
February 19th, 2007, 01:10 AM
i get a semi high pitched note thats constant
Yep, that is exactly what is intended. If you want to have some more fun, try something like this (spaces added only for increased readability):

10 POKE 54296,15:POKE 54278,240
15 FOR I=100 TO 0 STEP -10:POKE 54273,I
20 POKE 54276,33:FOR J=1 TO 50:NEXT J:POKE 54276,32:NEXT I
25 POKE 54296,0

It should make a sound that slowly drops in frequency. Anyway, I think your C64 is perfectly fine. Whether you choose to use the RF output or a dedicated video cable is your choice. As I wrote, if you are planning to connect the C64 to an amplifier, mixer or such, you will need to utilize the video/audio port to get the pure audio signal.