Search found 116 matches

by JonB
19 Oct 2016 16:35
Forum: CP/M
Topic: Help request: Patching a CF card driver in CP/M 2.2
Replies: 4
Views: 3332

Help request: Patching a CF card driver in CP/M 2.2

One for the CP/M hard core guys... and apologies if you read the same question elsewhere! I'm writing a CF adapter driver for a vanilla CP/M 2.2 implementation. The read and write routines are already written and working on a different CP/M device. They use a non standard interface because they're p...
by JonB
08 May 2016 11:11
Forum: OFF TOPIC
Topic: Yet another ZX Spectrum !!
Replies: 4
Views: 2448

Re: Yet another ZX Spectrum !!

Hi Lez Looks real enough.. there was much discussion about over at VCF, although I'm pretty cynical about it myself as I have several of the real things right here, so don't really need it. Another option was mooted ( http://www.cnx-software.com/2016/02/08/k3-wintel-keyboard-pc-specs-unboxing-and-te...
by JonB
01 Jan 2016 18:08
Forum: PROGRAMMING
Topic: C & Assembler conundrum
Replies: 6
Views: 4573

Re: C & Assembler conundrum

Bill B wrote:Indirect addressing on Z80 is most efficient using HL.
I did wonder. I suppose I wanted it working first! Yes, 3 t-states with HL vs BC..

(edit:seems to be broken again. I think it is psect areas conflicting)
by JonB
01 Jan 2016 18:06
Forum: PROGRAMMING
Topic: C & Assembler conundrum
Replies: 6
Views: 4573

Re: C & Assembler conundrum

This is the problem. I am developing it on CP/M with Hi-Tech C 3.09 and there is some corruption going on. Unfortunately the manual, while detailed, doesn't give much guidance on embedding assembler inline in a C program (which this is - and I'm trying to optimise it). It seems to be stable with the...
by JonB
01 Jan 2016 17:21
Forum: PROGRAMMING
Topic: C & Assembler conundrum
Replies: 6
Views: 4573

Re: C & Assembler conundrum

Or this: #asm psect text global _Curschar global _Fileend ;Init ld bc,(_Fileend) ;p=Fileend loop1: dec bc ;p-- ld a,(bc) ;get char to be moved (swap=*p) inc bc ;copy it (p++) ld (bc),a ;..to p (*p=swap) ld h,b ld l,c ld de,(_Curschar) ;have we reached the insert point? dec bc ld a,h cp d jp nz, loop...
by JonB
01 Jan 2016 16:44
Forum: PROGRAMMING
Topic: C & Assembler conundrum
Replies: 6
Views: 4573

C & Assembler conundrum

Here's a straightforward bit of programming for you! Consider the following C code: char *p; for ( p=Fileend; p>Curschar; p-- ) { *p = *(p-1); } What it does is move a block of memory from Curschar to Fileend one byte up (to open a place in a buffer for a character that's about to be inserted). I re...
by JonB
07 Sep 2015 17:29
Forum: CP/M
Topic: CP/M Boot Menu?
Replies: 4
Views: 4092

Re: CP/M Boot Menu?

You could get the menu program to inject the launch command direct into the CCP's command buffer then jump to the routine that interprets it.. Now that would be cool, but you would need to work out where everything is by disassembling the CCP and comparing with a copy of the source (such as the one ...
by JonB
26 May 2015 00:01
Forum: OFF TOPIC
Topic: What other retro machines do you have?
Replies: 26
Views: 12671

Re: What other retro machines do you have?

Quick update, I scored some more retro swag Another 48k Speccy Apple G4 iMac "lamp stand" G3 iMac "snow" Dual G4 PowerMac Tandy TRS-80 Model 4 128k, dual drives, hard drive via CF card Tandy TRS-80 Model II with 8" floppy A Multicomp (not retro, a sort of hardware emulation designed by Grant Searle)...
by JonB
04 May 2015 10:28
Forum: OFF TOPIC
Topic: Amazing homebrew ZX Spectrum & Amstrad CPC
Replies: 7
Views: 3812

Re: Amazing homebrew ZX Spectrum & Amstrad CPC

That's true Mark and as I recall no one was worried about waiting for orders to come in - it was the lack of communication after handing over your cash that worried people. If Zaxon's improved in this respect that can only be for the good.
by JonB
03 May 2015 20:32
Forum: OFF TOPIC
Topic: Amazing homebrew ZX Spectrum & Amstrad CPC
Replies: 7
Views: 3812

Re: Amazing homebrew ZX Spectrum & Amstrad CPC

Zaxon had an... errm... allegedly mixed reputation on the Atari forums with UltraSatan units. Just saying... Assuming it's the same guy.