Commodore 64 bread bin help

scoobyatgb

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I just got a commodore 64 bread bin version And it did have a fault with it black screen I change over from my other c64 same version the vic chip and the pla chip and then it started too work but I load a game on it and when the game stops loading it just crashes I know the game works as I have loaded it in the c64 i borrowed the chips out of is there a way of making a diagnostic cartridge with a EPROM so I can see if the other chips are ok or how would I work it out without that also were could I get a new pla chip for it
 

stephenfalken

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Commodore 64 bread bin help

I made a 'Dead Test' EPROM which works by placing it in the C64 Kernal socket. When turning on the C64 it boots the commodore dead test diagnostic. See it in the socket here ImageUploadedByTapatalk1432883626.180519.jpg

You could try this, I used a standard 27c256 chip.

It is also possible to make an EPROM based PLA, but these are hit and miss on which machines they work on, I have had a lot of success with them but get the occasional C64 which they won't work on.

Games crashing when loaded could be a RAM issue. Does the C64 show the correct number of bytes free on the BASIC screen? It should be 38911z


Regards
 
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scoobyatgb

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On the screen it reads 38911k for the memory how too you make one of the EPROMs you are talking about deans we're would you get the file too put onto it
 

stephenfalken

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You will need an EPROM and programmer then the bin file. All can be obtained cheap however, they are most useful for C64s which won't turn on at all. Since yours does work and get to the basic screen you may be able to try a software diagnostic, not sure of their names but they definitely exist.

Regards
 

scoobyatgb

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I have the programmer were would I get the bin file and do you just plug it in
 

roy_bates

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you would need to modify that 27c128/27c256 eprom to fit electrically to the socket on the c64

does it crash after it load or during?
 
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roy_bates

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AmiBayer
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disk or tape?

try cias or cpu first

you modify it the same way as you would for the kernal for jiffydos.

yes you could put it in a cartridge still might have to modify it though
diagnostic carts arnt much good without the harness anyway,it will be limited.
plus the machine has to be mostly working for it to diagnose anything...trust me i know.


EDIT: instead of mucking around like this why dont you just send it to someone who can fix it?
 
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scoobyatgb

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It is tape

how do you mod it for jiffy dos

how for the cias and cpu you mean just change then over for the working c64
 

roy_bates

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AmiBayer
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probably just ceramic disc caps nothing interesting...

i dont use a diagnostic cart,lol
 

roy_bates

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AmiBayer
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hang on a sec...

0.1uf probably around the 25 volt range...
 
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scoobyatgb

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Thanks for that roy one last thing we're would I get a user port and cassette port that is cheap
 
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roy_bates

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AmiBayer
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user port? you mean the edge connector?

cassette prom?


if its the edge connector for the both ports,ive seen them sold on ebay
 
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scoobyatgb

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Found roy thanks for that on the wiring diagram page 2 the serial dongle were to I wire the cable too I take it pin 1 and 5 go together and then pin 4 to 3 go together but is there more too wire up or am I missing something
 

roy_bates

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AmiBayer
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yes.

i think the reset and ground goes to the user port.
 
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