*** M E M O R U M ***

Agree, not all the BDOS is required for the SDX, but it is an interesting compromise: The simplest solution would have been to load the BDOS/BIOS in full, and place the file control blocks and other data structures below that. This would however use the maximum amount of high memory. Putting these d...

I have been trying to improve my understanding of exactly what use SDX BASIC makes of high memory (above 0xC000). The first thing I found is that only part of high memory is initialised when you first start the system. A lot more is loaded into high memory when you issue a USER command. To investiga...

Finally found the first issue with my USB Blaster clone. The ten wire data cable had been assembled with one of the connectors reversed :o I did not have a spare connector, and these IDC connectors are not meant to be removable. However, with some careful levering I was eventually able to remove the...

I have not had much free time to work on this recently, but I am making slow progress. At least I now know that my EPM7032S chips are not JTAG locked :) Altera developed the Jam Standard Test and Programming Language for defining the signals needed to program and test JTAG devices. The idea is that ...

A couple more PCBs have arrived from Lez: Another ZX Spectrum Clone: SuperFo Harlequin Rev 6. A much smaller board: RC6502 Apple 1 Replica, Revision F (pictured). Lez suggested Martin should have first refusal on this one. Apple_1.png I also still have from the first batch: ZX Max 48 - This one uses...

I knew it would not take you long

Lez will be pleased that at least one of the boards he supplied has been put to use.

20200208_131107.jpg 20200208_131043.jpg My boards for testing 7032 CPLD and USB Blaster on a breadboard. Now need to investigate whether I can program any of the chips. One advantage of having made these is that I can also test the logic of the programmed CPLD independent of the main circuit. Makin...

Dave, Many thanks for the offer. However I am using the smaller 7032S in my design. I have five of these chips from Lez, so hopefully at least a couple should be usable, even assuming that this is the problem. If not I will have to buy some more. I have also been wondering how the master programmer ...

Dave, That issue had occurred to me, and is a possibility. I am not sure there was an error message, other than "Failed", when attempting to program. When I did the JTAG test, I got the "No device found" message. I don't remember exact messages, and don't have the system in front...

Martin,

Thanks for the suggestion. It may be that, but I don't think so. The lead seems to be good quality and a good fit. Also there is activity on the programmer LED when attempting to program.

Experimentation is required.