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Bios replacement


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Just trying out some eeproms, winbond w27c512 anyone else use one of these for the no delay bios?

 

I do a write and verify, data all seems to be there, but coleco fails to boot. Starting at 000000...

 

Is this chip incompatible?

 

Thanks.

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Ok, so it does work.....

 

However, if all else fails read the data sheet. ;)

Tie the extra data lines etc to ground, if it's just straight socketed, pins 1, 26, 27, are tied to pin 28 and 28&1 are tied high.(+5), so slight rework is needed.

 

A 27c64 would make things much easier, plug and play.

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Ok, so it does work.....

 

However, if all else fails read the data sheet. ;)

Tie the extra data lines etc to ground, if it's just straight socketed, pins 1, 26, 27, are tied to pin 28 and 28&1 are tied high.(+5), so slight rework is needed.

 

A 27c64 would make things much easier, plug and play.

good luck finding a programmer that programmes that chip

my programmer which supports over 10000 devices wont do it

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If your using something like the mini pro, it should work. Try turning the menu off and go bare bones.

 

http://atariage.com/forums/topic/230688-tl866cs-minipro-eprommer/

ok i miss read the chip and made assumptions, it seems like my xeltek superpro 3000u does in fact support 27c64

the chip i was thinking of was an 'MCM68766C' which i have a partial device match only of 'MC68766', and when attempting programming the chip only programs one byte before failing because the programmer doesn't know how to tell the chip to move onto the next byte.

 

this chip is a direct bios chip replacement as it has exactly the same pinout as the colecovision bios and the same pin count for the 24 pin 'normal' chip. i have since found an adaptor to convert a different device with more pins to the right pin configuration but its a bit tight as it just misses the inserted cartridge by about a piece of paper width so is not ideal

 

perhaps the 27c64 is also a direct pin replacement (24 pins too)?

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You must be dealing with a European coleco. The North American one has "extra" holes allowing you to change to a common 28 pin eprom. The 27c64 is a 28 pin eprom.

yes I am lumbered with the brokenness of European pal coleco's :/

 

i will attempt to start work on the buggered USA coleco board that i obtained recently tonight and see what i can do with it obviously i cant test the video output due to pal / ntsc incompatibility but i can take a fair guess of it working by the sound output pin of the sound chip

 

 

that was one of my great disappointments with the European board the lack of the holes to make a more useful EPROM work, not to mention the general poor quality of the board lol

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So first off you could be looking for the holy grail. The TMS27C49, 24 pin eprom.

 

However since space is limited,

I'm amazed no one has cooked up an adapter board as of yet.

 

Say PLCC or SOIC to the uncommon 24 pin output.

(depends on where the space is limited.)

 

Or even an adapter board to "move" the chip over. Some perf board and a couple of sockets should get you there,

however I'm not sure if the PAL board is reconfigurable to accept the 28 pin eprom.

 

Some pictures might help. ;)

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