Rare Pre-Production VIC-20 Cartridges

ral-clan · Post by **ral-clan** » Fri Apr 24, 2009 11:32 am

Hi guys,

Here is the re-dumped block 5 from Gorf_EPROM and a dump of the Bing Math cartridge which I could not get to start:

http://www3.sympatico.ca/clarke-santin/ ... extras.zip

I am interested to see the results of analysis.

By the way, with both versions of GORF that I dumped, I noticed that the letter "C" in the word SCORE at the top of the screen had some yellow pixels in it. Is that something that made it into the final commercial version?

Mike · Post by **Mike** » Fri Apr 24, 2009 12:36 pm

With Bingo-Math, only BLK5 seems to contain EPROM data.

Within 64 byte blocks, a 16 byte sequence often repeats 4 times, before changing to another byte sequence.

This could indicate, that the address lines A4 and A5 might be the cause of the problem, like small cracks in the copper traces. Or oxidated pins of the ROM chip in the socket: I took a look at the cartridge photo; did you try to re-seat the ROM chip?

Greetings,

Michael

ral-clan · Post by **ral-clan** » Fri Apr 24, 2009 1:13 pm

Yes, I did try to reseat it. The edge connector was also quite oxidized, and I have cleaned it with alcohol several times.

6502dude · Post by **6502dude** » Fri Apr 24, 2009 2:08 pm

ral-clan wrote:Yes, I did try to reseat it. The edge connector was also quite oxidized, and I have cleaned it with alcohol several times.

If you have a multimeter, try buzzing out connection from edgecard to eprom pins. This should identify if you have an open connection somewhere.

ral-clan · Post by **ral-clan** » Fri Apr 24, 2009 2:12 pm

Sure, I can do that - if it's a straight continuity test.

Mike · Post by **Mike** » Fri Apr 24, 2009 2:48 pm

If you put the circuit board with the soldering side up, and the edge connector pointing to you, the edge contacts from left to right are:

GND, A0, A1, A2, A3, A4, A5, ... (these correspond to A, B, ... of the cartridge expansion port),

and there are straight connections from A4, and A5 to the socket pins.

Michael

KilrPilr · Post by **KilrPilr** » Fri Apr 24, 2009 2:48 pm

Brent, take a pencil eraser to the contacts to clean them and remove the oxidation/rust/dirt. Works much better than alcohol.

ral-clan · Post by **ral-clan** » Fri Apr 24, 2009 3:00 pm

Actually, I did try this too. Thanks for the tip, though.

carlsson · Post by **carlsson** » Sat Apr 25, 2009 4:36 pm

If you reseated the EPROM (I presume), what prevents you from lifting it completely and temporarily insert into another similar cartridge which was possible to read? Or if you had an EPROM programmer on your desk, you could insert the chip and dump it from there.

ral-clan · Post by **ral-clan** » Sat Apr 25, 2009 7:06 pm

carlsson wrote:If you reseated the EPROM (I presume), what prevents you from lifting it completely and temporarily insert into another similar cartridge which was possible to read? Or if you had an EPROM programmer on your desk, you could insert the chip and dump it from there.

These are not my cartridges, and they were quite expensive. So there's only so much fooling around I want to do with them. It is worth considering what you suggest though.

KilrPilr · Post by **KilrPilr** » Sat Apr 25, 2009 7:16 pm

I have an eprom burner/reader so if its ok with Paul and you want to send them to me, I can dump the eproms and then send them back to Paul. lmk

PaulQ · Post by **PaulQ** » Mon Apr 27, 2009 5:08 am

ral-clan wrote:
dragos wrote:I am truly at a loss to understand why on earth you would volunteer to do something and possess none of the knowledge required to do it....
4) Denial members have kindly answered my questions about dumping cartridges and now I can do it.

5) It's called co-operation.

I, for one, completely understand the nature of this. One often "Volunteers" to do something because they will benefit from the learning experience that comes from learning how to perform the task. As such, the reward to the volunteer is learning something they previously did not know. Absolutely nothing wrong with that; it's a win-win situation. I cannot imagine why someone would criticize your intentions, unless criticizing you gives them a puffed-up satisfaction and a feeling of control that provides short-term relief from uneasiness.

dragos · Post by **dragos** » Mon Apr 27, 2009 8:09 am

No hope...

Post by **Jeff-20** » Mon Apr 27, 2009 10:51 pm

This is like a surreal cartoon... hahahaha

JagMod · Post by **JagMod** » Tue Apr 13, 2010 10:29 pm

I built a small device to dump the carts.

http://www.jagmod.com/avi/VicRomId.avi