Commodore VIC-20 Help

[Atari PAC-MAN Fan]

Hey Guys!

 

I got a Commodore VIC-20 yesterday. It works, but won't read carts. Isn't it supposed to boot right to the cartridge if you have it inserted? It's in great condition, it powers up to the BASIC screen, but it just refuses to read carts. I even had someone clean the machine on the inside and it still does not read carts. Please Help!

[+SpiceWare]

By chance are they the Scott Adams adventure games? Those require you to manually start them, from the manual:

TYPE THE FOLLOWING TO START THE GAME: SYS 32592 (and hit the RETURN key)

The VIC will display the title page of the adventure and asks if you want to restore a previously saved game. If you are starting a new game, type NO (and hit RETURN). If you are restarting a previous game you've SAVED, see the section on SAVING AND LOADING ADVENTURES.

If not, try cleaning the cartridge contacts with Q-Tips soaked in rubbing alcohol.

 

Additionally try cleaning the cartridge port on the VIC itself. This is what I did last time I cleaned my 2600's cartridge port, same trick should work with the VIC.

To clean your cartridge port try flattening the Q-Tip with a pair of pliers before soaking them in alcohol, then insert/remove the flattened end a few times in each position of the cartridge port (unused Q-Tip on bottom for comparison):

 

 

[carlsson]

Some utility cartridges like Programmer's Aid also doesn't autostart, due to an ambition to being able to combine multiple cartridges and thus some were wired to non-autostarting memory areas.

 

But yes, it sounds like further cleaning might be in order. A brief look at Ray Carlsen's document about common faults doesn't list a situation where cartridges don't work but the computer otherwise is fine, but perhaps a cut line or two might cause problems.

[bpatte02]

Perhaps a contact cleaner on the pins of the cart slot might also help, you can put it on a q tip and do the same thing that was suggested with alcohol. I would then use alcohol to dry It faster. Also helps cut the smell from lingering.

[Atari PAC-MAN Fan]

The only game I own at the moment for the VIC-20 is Donkey Kong.

[simbalion]

None of my Adventure cartridges I got with my first VIC would work either, until I remembered to clean them. After that, no issues as long as I remembered what code to type in. The VIC is a neat little gaming machine once you get it going. My only issue is how tight the carts fit in both of my VIC 20s. Got an early and a mid production unit.

[Atari PAC-MAN Fan]

Can you guys tell me what the command is to run Donkey Kong? Maybe I just don't know the right commands. I have already tried typing run with the cart inserted. It did not do anything.

Edited March 25, 2017 by Atari PAC-MAN Fan

[Atari PAC-MAN Fan]

Ok. I just cleaned the cartridge and the cartridge port. I did not work.

[BassGuitari]

Can you guys tell me what the command is to run Donkey Kong? Maybe I just don't know the right commands. I have already tried typing run with the cart inserted. It did not do anything.

Donkey Kong will autoboot. The only game cartridges that come to mind that don't are the Scott Adams Adventure games, like others have said--those boot with a SYS command (SYS23582 or some such, I forget exactly.)

 

You could just have a bad cart. Incidentally, my copy of Donkey Kong also doesn't work, no matter how much cleaning I do (it's a very clean cart). I've got two other [very clean] carts that just won't have it, either. Gotta be some kind of internal failure.

[bpatte02]

Perhaps picking up a cheap cart such as slots or poker might allow you to check to make sure its not the game itself.

[simbalion]

Like BassGuitari said, you can actually run into bad carts. Heck, I've even found a couple for the Atari 2600 over the years. I have a Berzerk that won't work no matter what I try. Like said earlier, try to see if you can find another cheap cart or two to try out in the system first. If it's booting up without the carts, I would say the chances are good it will work with carts.

Edited March 25, 2017 by simbalion

[carlsson]

Pin 13 (upper row) connects to BLK5 (40960 - 49151) which is the one that would autostart. Donkey Kong contains 16K arranged into BLK1 (8192-16383) on pin 10 plus the mentioned BLK5. You could visually check that these lines aren't broken on the cartridge. But yes, if you can obtain a second cheap cartridge it would help some.

 

Actually you can do some checks in BASIC too. Normally addresses 8192 - 16383 would contain 0, 255 or bus noise as long as you don't have any RAM (most common) or ROM (unusual) connected there. That means if you type in this, you can read if there is something in memory at all:

 

FOR A=0 TO 40:PRINT PEEK(8192+A);:NEXT

 

You should get a display like this:

 

If you get mostly 0 and 255, it is a sign the cartridge isn't seen by the computer for one reason or another. If you do get a matching display, you know it partly works.

Edited March 25, 2017 by carlsson

[Atari PAC-MAN Fan]

Oh. Now I get what you all are saying. I just wanted to get Donkey Kong because I know it's sort of rare for the VIC-20. I did what carlsson said about the "BASIC" thing, and yeah. I think I do just have a bad cart. I'll go and pickup Commodore Avenger (since it's a Space Invaders clone and also really cheap). I'll check to see if it has all the pins or at least most of them. I'll post about how it turns out. Thanks for all the help!

[+SpiceWare]

I'll go and pickup Commodore Avenger (since it's a Space Invaders clone and also really cheap). I'll check to see if it has all the pins or at least most of them.

 

 

It'll be missing a bunch of pins. Front:

 

Back:

[Atari PAC-MAN Fan]

What are the pins it has to have to function?

[+SpiceWare]

It depends on what's inside the cartridge. A lot of my C= games are missing the exact same pins as Avenger, while other games use more pins. Demon Attack is missing a few that Avenger has, so is probably a smaller ROM which would need fewer pins to connect it to the VIC.

[carlsson]

A 8K ROM cartridge only needs one of the pins 10-13 to select block, and probably none of pins 14-16 which are for RAM, pins T-U for I/O blocks etc. Generally you should be safe with the pins on the cartridge, but check so none is very worn or has suffered a cut further onto the cartridge circuit board. It shouldn't happen, but one never knows.

[Jess Ragan]

Kind of a shame. The VIC-20 port of Donkey Kong is very good, considering that system's limitations.

[Grimakis]

Could be the computer. On my C64, i could not use the Epyx Fast Load, or DigDug.

 

I sent it Ray Carlsen, he check it out, said nothing was wrong, must be a marginal power supply.

 

Sent it back with a good PSU. Still didn't work. I sent it back, and he pulled chips one by one. It turned out to be the PLA with a partial failure that kept it from working with SOME carts.

 

So it could be an issue with the cart, the PSU(extra load could cause issues) or perhaps a failing IC

[RobertB]

It turned out to be the PLA with a partial failure that kept it from working with SOME carts.

I've heard it from Ray time and time again that intermittent problems are the hardest to diagnose.

BTW, I'm having Ray repair a PAL VIC-20 for me right now.

 

Back in California,

Robert Bernardo

June 10-11 Pacific Commodore Expo NW -

http://www.portcommodore.com/pacommex

July 29-30 Commodore Vegas Expo v13 -

http://www.portcommodore.com/commvex

Edited March 30, 2017 by RobertB

[Grimakis]

I've heard it from Ray time and time again that intermittent problems are the hardest to diagnose.

BTW, I'm having Ray repair a PAL VIC-20 for me right now.

 

Back in California,

Robert Bernardo

June 10-11 Pacific Commodore Expo NW -

http://www.portcommodore.com/pacommex

July 29-30 Commodore Vegas Expo v13 -

http://www.portcommodore.com/commvex

 

No doubt that Ray is a champion among C64 enthusiasts. I've got one of his "System Savers", and one of his custom PSUs. And of course he fixed one of my C64s.

[carlsson]

Since there is no PLA chip in the VIC-20, I'm idly wondering what else could cause a similar problem. I don't know the hardware that well to pick from a schematic but usually it is the other way around, that if some of the internal ROMs are bad, at least carts may work. I'd suggest that the OP tries to obtain, perhaps loan locally if you know anyone, a second known working cartridge or even offer to lend your current Donkey Kong cartridge to a trustworthy person who can identify if it works in another computer.

 

Besides that game is not particularly rare. The Digital Press online guide lists it as a 3/10 with a value loose of $4. I think Mayhem keeps the guide up to date and at least the rarity rating should be quite stable. But sure, it is quite playable just like most of the Atarisoft titles.

 

Does the cartridge circuit board sit steady in the case? Sometimes the plastic pins are broken, so the board will rotate to either direction when you shove it in and not get proper contact with the connector. If the cartridge is openable - watch out so no plastic hinges are broken apart if you try to open it - you could try the PCB itself in that case.

[Mayhem]

Yeah, finding a replacement Donkey Kong cart shouldn't be an issue if you need to replace it.

[Grimakis]

Since there is no PLA chip in the VIC-20, I'm idly wondering what else could cause a similar problem. I don't know the hardware that well to pick from a schematic but usually it is the other way around, that if some of the internal ROMs are bad, at least carts may work. I'd suggest that the OP tries to obtain, perhaps loan locally if you know anyone, a second known working cartridge or even offer to lend your current Donkey Kong cartridge to a trustworthy person who can identify if it works in another computer.

 

Besides that game is not particularly rare. The Digital Press online guide lists it as a 3/10 with a value loose of $4. I think Mayhem keeps the guide up to date and at least the rarity rating should be quite stable. But sure, it is quite playable just like most of the Atarisoft titles.

 

Does the cartridge circuit board sit steady in the case? Sometimes the plastic pins are broken, so the board will rotate to either direction when you shove it in and not get proper contact with the connector. If the cartridge is openable - watch out so no plastic hinges are broken apart if you try to open it - you could try the PCB itself in that case.

 

Yes, I agree, testing the cartridge in another setup will help troubleshoot. If it works on another VIC-20, then troubleshoot your own setup more. If it does not, then assume the cart is bad and acquire a replacement.

[Atari PAC-MAN Fan]

Thanks Everyone! Turns out I did just have a bad cart. I'm kinda mad because I paid $20 for it and gave the guy good feedback because I thought the console was the problem. Anyways, thanks for all the advice.