Search found 237 matches

by Bill B
26 Mar 2020 19:39
Forum: BASIC
Topic: SDX High Memory
Replies: 10
Views: 713

Re: SDX High Memory

Thinking about this has raised a side question: Was there ever a manual for SDX BASIC? I never had one, and I don't see one on Dave's site. There is documentation for FDXB, and mostly you can just replace "DISC" by "USER". But FDXB relies upon CP/M to do disk formatting. So there are some commands t...
by Bill B
26 Mar 2020 17:10
Forum: BASIC
Topic: SDX High Memory
Replies: 10
Views: 713

Re: SDX High Memory

It turns out that functions #25 and #28 are implemented in CP/M 2.2, see the source here . Presumably just not documented. I suppose what I am really questioning is why SDX makes use of the system tracks from the drive rather than just implementing everything in ROM. Was it really much quicker to sp...
by Bill B
26 Mar 2020 10:06
Forum: BASIC
Topic: SDX High Memory
Replies: 10
Views: 713

Re: SDX High Memory

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...
by Bill B
24 Mar 2020 18:26
Forum: BASIC
Topic: SDX High Memory
Replies: 10
Views: 713

SDX High Memory

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...
by Bill B
21 Mar 2020 18:00
Forum: OFF TOPIC
Topic: Another Home-Brew - Z180
Replies: 53
Views: 8134

Re: Another Home-Brew - Z180

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...
by Bill B
07 Mar 2020 22:14
Forum: OFF TOPIC
Topic: Another Home-Brew - Z180
Replies: 53
Views: 8134

Re: Another Home-Brew - Z180

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 ...
by Bill B
17 Feb 2020 19:20
Forum: OFF TOPIC
Topic: PCBs for Spectrum Clones
Replies: 17
Views: 1739

Re: PCBs for Spectrum Clones

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...
by Bill B
10 Feb 2020 11:33
Forum: OFF TOPIC
Topic: PCBs for Spectrum Clones
Replies: 17
Views: 1739

Re: PCBs for Spectrum Clones

I knew it would not take you long :D

Lez will be pleased that at least one of the boards he supplied has been put to use.
by Bill B
08 Feb 2020 15:33
Forum: OFF TOPIC
Topic: Another Home-Brew - Z180
Replies: 53
Views: 8134

Re: Another Home-Brew - Z180

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...
by Bill B
03 Feb 2020 10:18
Forum: OFF TOPIC
Topic: Another Home-Brew - Z180
Replies: 53
Views: 8134

Re: Another Home-Brew - Z180

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 ...