Sinclair ZX80 / ZX81 / Z88 Forums

sP1d3r wrote: ↑Tue Jul 19, 2022 8:51 pm Your C31 (100nf IIRC) looks gone.

That's true, I noticed the black, burn ring, but I am not worried about it as it is on MIC line. I want to make sure all 48K of RAM are in working order before going to fix other smaller issues.

Thanks, Mark. [...] By the way, which ULA version do you have in this board? Sinclair discovered that the original design was marginal on the DRAM timings, hence in later boards, the timing for the “lower” DRAM was changed slightly. Mark The ULA version is 5C112E-3 I think (see the picture below). h...

The version I'm using is not the latest (0.37), but one below (0.36D). I run the Soak Test as explained on the GitHub page: If the 'S' key is held down when the machine is powered on, the firmware enters soak test mode (signified by a third high pitched tone immediately after the initialisation tone...

Thanks, Mark. In my previous message, I have incorrectly assumed that RAM 0 FAIL refers to the first RAM chip of the lower RAM., whereas there is no "zero" in the error message. I followed your instructions and disabled the upper RAM. Now, when using the Retroleum DiagROM, I consistently get the exp...

Hello, I am testing a Spectrum 48K Issue 2 using the " ZX External ROM " sold by MyRetroStore. The ROM is loaded with four diagnostic tools, two of them being "Retroleum DiagROM v1.56" and "Brendan Alford Diagnostics 0.36D". Before removing IC25 and IC26, Retroleum DiagROM was reporting IC25 and IC2...

Lardo Boffin wrote: ↑Thu Jun 02, 2022 6:53 pm I have had ZX81 ROMs done here:

https://www.mutant-caterpillar.co.uk/shop/

Thanks for the link. I have contacted them - I will post here when I get any feedback.

I don't have a programmer suitable for programming 27128 EPROMs. Is anyone out there offering this kind of services? I have two such chips and I would like to have them "burnt", one with a Spectrum 48K ROM and another one with a Spectrum 48K clone ROM.

Many thanks for your feedback. @Paul, I don't have the TL866CS; I was looking to get one, until I discovered that, with help from some adapters , I can use my Retro Chip Tester as an EPROM programmer. I don't know yet how viable this solution is and how well it works, but I will find out soon enough...

Hello,

I need to write the ZX Spectrum 48K ROM into four 2732 EPROM's (Mitsubishi M5L2732K). I assume I need to find a "way" to split the 16384 bytes "48k.rom" file into four files of 4096 bytes each. What Windows / Linux / macOS program shall I use to achieve this?

Hello, my first post here so hopefully somebody will help a newbie. I just assembled a Rev G 48k Harlequin after my spectrum sadly died. I burned a 27C256 using my TL866CS. But alas upon startup all i get is this.. could it be rom-related? Any leads to the possible culprit?IMG_6115.MP4 Did you burn...