Search found 449 matches

by Martin A
03 Apr 2020 21:36
Forum: PROGRAMMING
Topic: Coding Challenge
Replies: 4
Views: 33

Re: Coding Challenge

Martin, I like the "PUSH HL / LD HL, value / EX (SP), HL" sequence. Not seen that before. I stole that from the MTX rom :lol: It's at #00BC .pend 0089 E3 EX (SP),HL 008A F5 PUSH AF 008B 7D LD A,L 008C E6 70 AND &70 008E 67 LD H,A 008F 3A D2 FA LD A,(PAGE) 0092 E6 8F AND &8F 0094 B4 OR H 0095 32 D2 ...
by Martin A
03 Apr 2020 14:44
Forum: PROGRAMMING
Topic: Coding Challenge
Replies: 4
Views: 33

Re: Coding Challenge

OK, totally untested, here's my first take on the re-entrant version: The only thing I know for certain is it builds ! Z80 Cross assembler V1.77 Source File MTX.Challenge Build 1 Pass 2 FAD2 page equ &fad2 0000 pageport equ 0 .farcall2 0000 F5 push af ; save the original af value, exit will need it ...
by Martin A
26 Mar 2020 21:14
Forum: BASIC
Topic: SDX High Memory
Replies: 10
Views: 57

Re: SDX High Memory

The MTX wouldn't be the first system of that era, overwriting a program in memory. The C64 would do that getting a directory listing. Acorn DFS needed a separate format program trashing the program in memory. I haven't looked, but I'd hazard a guess SDX USER FORMAT probably wasn't too careful where ...
by Martin A
26 Mar 2020 17:57
Forum: BASIC
Topic: SDX High Memory
Replies: 10
Views: 57

Re: SDX High Memory

FDXB seems to have a vanilla copy of a large chunk of the BIOS/BDOS in it's final 8k. That too only uses the disc functions and probably for space reasons doesn't include the low functions at all. That top 8k also has to hold the low level drivers for the screen and discs as well as the basic extens...
by Martin A
26 Mar 2020 15:49
Forum: BASIC
Topic: SDX High Memory
Replies: 10
Views: 57

Re: SDX High Memory

I imagine the main reason was compatibility, or possibly speed of implementation. The SDX used the same discs as the FDX. Which means the BIOS/BDOS is optimised for CPM. The SDX just makes the best use of the "borrowed" code. When I got the upgrade form the original big box SDX to CPM, FDXB was able...
by Martin A
25 Mar 2020 00:36
Forum: BASIC
Topic: SDX High Memory
Replies: 10
Views: 57

Re: SDX High Memory

The SDX only uses the BDOS part of CPM. It has the BASIC ROM calls for things like keyboard and display handling.

All of the function calls below 12 or so are redundant. I'm on the wrong computer to check the SDX rom source, but I'm not sure it even loads the BIOS tracks.
by Martin A
08 Mar 2020 15:08
Forum: OFF TOPIC
Topic: Another Home-Brew - Z180
Replies: 53
Views: 5638

Re: Another Home-Brew - Z180

If you have a "spare" EPM7128, you could shove that into the CFX-II and test your USB blaster with that. And hopefully confirm that it is working.
by Martin A
11 Feb 2020 00:03
Forum: OFF TOPIC
Topic: PCBs for Spectrum Clones
Replies: 17
Views: 791

Re: PCBs for Spectrum Clones

So, is anyone else ready to take up the challenge ?
by Martin A
09 Feb 2020 18:27
Forum: OFF TOPIC
Topic: PCBs for Spectrum Clones
Replies: 17
Views: 791

Re: PCBs for Spectrum Clones

It's built, I had nothing better to do while sheltering inside from storm Ciara, so I've finished the Harlequin 128 build. Here's the board with everything except the rom added just the rom to add.jpg Now with the rom fitted and the keyboard mounted completed.jpg The 512k flash has room for 8 differ...
by Martin A
08 Feb 2020 23:50
Forum: OFF TOPIC
Topic: PCBs for Spectrum Clones
Replies: 17
Views: 791

Re: PCBs for Spectrum Clones

I think (I hope!) that's all the soldering done, I'll do some basic tests tomorrow and then start populating the ICs.
all soldering done I hope.jpg
all soldering done I hope.jpg (145.97 KiB) Viewed 366 times