Colecovision PAL BIOS Swap...

[Sparkoids]

Hi guys,

 

I have tried two Coleco boards now to try and get the F18A VGA adaptor working to no avail. It seems that unfortunately the adaptor doesn't work on European Colecovisions.

So I am trying to swap the PAL bios out of the unit for a "No Delay" version which someone on this fine forum said would help.

 

However after getting the eproms ordered it seems the 27C64 is a 28 pin device and I just assumed the chip on the board was the same but it isn't unfortunately :-{

 

Worse I cannot find a data sheet for the 24 pin TMS4764NL prom anywhere.

 

Has anyone got a data sheet for the device please so I can check the pinout and has anyone actually done a BIOS swap on a PAL Colecovision?

 

Here's hoping and thanks in advance...

 

 

James :-}

[alex_79]

TMS4764.pdf

I don't think you'll find a pin compatible EPROM for that chip. You'll have to build an adapter to use a 27C64.
You must first determine if the chip select pin (pin 20) is active high or low, as it could be programmed in both ways during fabrication. If it's active high, you'll need also an inverter on the adapter.

Edited December 3, 2016 by alex_79

[Sparkoids]

Ok the BIOS is removed. (Kapton tape around device, preheated the board then removed it with a selective wave solder machine - fitted socket, tested and the BIOS still works).

 

 

Does anyone have an actual PAL dump of the BIOS for me to check please?

 

My programmer can't read the TMS4764 or NEC D2364 device :-{

 

Adaptor to follow tomorrow or Wednesday. Thanks for the help Alex_79....

 

 

[NIAD]

Here's dumps of the BIOS from a PAL system and French Scart system...

 

 

CBS ColecoVision BIOS - OS7 (1982) (CBS Electronics) (PAL).zip

CBS ColecoVision BIOS - OS7 (French RGB-SCART) (1982) (CBS Electronics) (PAL).zip