Sinclair ZX80 / ZX81 / Z88 Forums

as for using this with a zxpand, could be problems as this needs to patch out the rom under refresh cycles, will need to mod the zxpand so its rom and the zx rom can be disabled...

wilf or someone else may have already done such a thing,..????

regardless of the zxpand, there 'might' be a way of an external udg unit..wilf rigters chrsx16 replaces the character set externally, but with a 'fixed' eprom, i tried to work out how to mod this circuit so it uses a ram and can be programmed at will making fully programmable character sets, i never...

you could try wiring a filter circuit in series with the composite out, tuned to reject the colour subcarrier frequency , may be possible to get a ready built 'module' ??? as for what frequency,? pal 4.433, ntsc 3.579, to cover all possibilities... one of each! ?

Andy, have you ever released publicly the details of the 6 gal 1 ttl version? i know of the all ttl thing and of course, the cpld module?

i know about the cpld module, i bought one is there info on a gal version around somewhere??

ula using gals??? where, where??!!

not really normal but used when they couldnt get enough mask roms, the 64k means 64k bits, or in normal terms 8k byte, this is how eproms were normally coded, 2564=64k bit, 8k byte...

better

i have a couple like that, same type eprom, 2564