Faulty 128K +2A

[walde123]

Some time has passed and I've got my hands on a TL866-II plus EPROM programmer. I haven't got any replacement EPROMs yet but I tried reading the ROMs from the Speccy and since it seemed to fail detecting PIN 1 which apparently is not connected in the ROM so I bypassed the pin detection and ID check and was able to get the contents of the 40093U ROM and the first half of it matches perfectly to the +2A/+3 v4.1 ROM 2 (+3DOS) found on here: http://www.shadowmagic.org.uk/spectrum/roms.html

I'm going to assume the other half of the ROM is fine too since the first half checked out but when I tried reading the 40092U ROM it just gives straight 0s, using the exact same settings as for the 40093 with simply swapping the chip in the socket in between attempts, so seems like to me that the 40092 is toast? or maybe I'm missing something. Anyway, I guess now I'll need to wait for the EPROMs to arrive so I can burn a replacement, I'm guessing there's some pin modification to do as well for using the EPROM since they expect 5V on pin 1?

[Guesser]

No you don't need to modify anything, it just plugs straight in.

[1024MAK]

To read the ROM chips from these machines, it’s best to manually select any brand/make of 27C256 EPROM. But only try to read from it, never try to write/burn to it.

Each of the two physical ROM chips contain two 16k byte ROM images. To see the other ROM image, get your programmer to read from 0x8000 (32768) onwards.

Just to add to what Guesser said... A 27C256 or 27256 EPROM chip can directly replace a ROM chip in these machines. No wiring or other changes are needed.

Mark

[walde123]

To read the ROM chips from these machines, it’s best to manually select any brand/make of 27C256 EPROM. But only try to read from it, never try to write/burn to it.

Each of the two physical ROM chips contain two 16k byte ROM images. To see the other ROM image, get your programmer to read from 0x8000 (32768) onwards.

Just to add to what Guesser said... A 27C256 or 27256 EPROM chip can directly replace a ROM chip in these machines. No wiring or other changes are needed.

Mark

Yeah I figured that would be the case, the machine is alive now so in the end the 40092U was bad, really glad it wasn't anything worse since in the end I only lost a few euros on some ram chips with some spares, and the eprom was only a few cents excluding the fact that I had to spend 40€ on the eprom programmer. Huge thanks to you and everyone else who helped me out. Still need to actually see if it can do anything but the startup screen is definitely a huge improvement over the garbled mess