Adding roms to NTSC TS1500

[redman]

last time - make that re-wiring

[1024MAK]

In the thread Converting ZX81 ROM Socket to 2764 EPROM there is this document

But for the TS1500, if it has a 24 pin socket, this is what you will need:-


Other useful links:-
ZX81 Chip Pin-outs‬

Replacing the ROM

Does anyone know the pin-out of the 28 pin socket that sits under my 24 pin ROM?

Burning a ZX81 rom

Mark

[Moggy]

Having supplied the said diagram in Marks post I can vouch that it works perfectly and have burnt many EPROMS (HForth Treeforth AZMIC SG81 etc)and rewired with this plan and all work ok.

The only stumbling block is that I never had much joy with the 12volt version of the 2764 (27c64 ?) and ended up buying a job lot of 21 volt devices which fortunately I can burn using my Spectrum EPROM programmer.
I only mention this as I once heard that modern (especially cheap Chinese) burners struggle with 21/25 volt devices, but having not owned one it could be anecdotal.

[1024MAK]

Nice photos Moggy. I did look for some, but did not find any good ones.

The issue with the cheap EPROM programmers, is that the ones designed to run from a 5V or USB supply can't maintain the 21V or 25V programming voltage. Hence they can program the first handful of memory address locations, but then fail to program the rest of the chip.

If you have one that has a separate 9V to 12V power input, and it has decent DC/DC converter circuitry, they can program 21V EPROMS. I know, 'cus I have one. Don't use it much these days, because it uses the parallel printer port for data transfer (as a serial data stream that must be bit bashed!)

Mark

[Moggy]

Thanks for that and for the info Mark.
The only burner I have runs off The ZX spectrum/ZX81(Eprom Services type 2 board) and uses three 9v batteries for programming.
I bought for use with the 81 as the guy who sold it said he had the 81 software but turns out it was the speccy program which meant buying a 48k+ only to find out it runs quite well on the +2a which I already had!

If anyone ever wants to replicate this burner just for nostalgias sake if nothing else then I am willing to photograph it , post the accompanying manual and software etc.

[dessony]

I concur with 1024MAK and Moggy 100% on the building a ROM adapter for the TS1500! The website, I abovementioned, explained us how to make the adapter in very detailed and even a set of these pictures exists. I compared both the web-link down here and this forum and they are exact same.

http://ist.uwaterloo.ca/~schepers/sockets.html

Cheers ,
Dessony