Search found 3129 matches

by jgharston
Sat Aug 18, 2018 3:54 pm
Forum: programming
Topic: Floating point representation examples?
Replies: 5
Views: 132

Re: Floating point representation examples?

(And yes this was to do with converting disc files. Next query would be the order in which the mantissa is written to disc.. The exponent is the fifth byte to be written in BOTH Acorn and Russell formats.. ) Try these: http://mdfs.net/Info/Comp/BBCBasic/ProgTips/BBCFile.vb http://mdfs.net/System/Li...
by jgharston
Sat Aug 18, 2018 1:50 pm
Forum: software & utilities for the pc, mac or unix
Topic: BBCSDL - Functional Differences from Other BBC BASIC implementations?
Replies: 45
Views: 447

Re: BBCSDL - Functional Differences from Other BBC BASIC implementations?

Most of what people have posted aren't differences in implementations of BASIC, but differences in the host OS that different implementations of BASIC run on. Of course you need to use SYS "SetWindowText", @hwnd%, "My Window Title" when running on Windows, because that's the Windows call; you would ...
by jgharston
Mon Aug 13, 2018 11:23 pm
Forum: software & utilities for the pc, mac or unix
Topic: Matrix Brandy BASIC V for Linux with SDL: V1.21.9 released
Replies: 175
Views: 2748

Re: Matrix Brandy BASIC V for Linux with SDL: V1.21.9 released

I've done some optimisations on the code - and added the facility to tune the polling interval to check for ESCAPE. It certainly runs faster for me (up from 85 to 125 on my CentOS 6 VM). That's certainly faster for me - around 300 (tried a few times). I am not having much luck with varying the Esca...
by jgharston
Mon Aug 13, 2018 7:53 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 146
Views: 2185

Re: Z80 Protocol Decoder

I can say more, once I have the PLD fully working in my mind. The Tube chip occupying the whole I/O map is a nuisance and the shadow ROM code would need modifying. I'll do a design for a simple standalone Z80 system first. If you're putting a sandwich under the Z08 then just add a bit of decoding t...
by jgharston
Sun Aug 12, 2018 8:46 pm
Forum: hardware
Topic: A5000 hard drive and mouse not working :/
Replies: 12
Views: 232

Re: A5000 hard drive and mouse not working :/

steve3000 wrote:
Sun Aug 12, 2018 8:41 pm
The mouse pointer wobbling in the middle of the screen suggests the IR LEDs have begun to fail inside the mouse itself.
Or that it's full of crud. Take the lid off and check the rollers are clean. I find the easiest way to do so it to use a finger nail to gently rub/scrape the crud off.
by jgharston
Sun Aug 12, 2018 8:43 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 146
Views: 2185

Re: Z80 Protocol Decoder

I vaguely remember reading that the PC=PC-2 is done using the JR silicon stuffing an offset of &FE into the process. Ah, faulty memory, I was remembering the JR cc,-1 trick to do a conditional RST &38. The PC=PC-2 uses the same increment/decrementer circuitry that is used for the normal 16-bit INCs...
by jgharston
Sun Aug 12, 2018 8:14 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 146
Views: 2185

Re: Z80 Protocol Decoder

After some investigation with help from BigEd and his real Z80 Co Pro, we've determined they come from bits 13 and 11 of the PC (i.e. the address of the LDIR instruction). That makes sense, as the last bit of execution done before an INT is responded to is PC=PC-2 which does PClo=PClo-2; PChi=PChi-...
by jgharston
Sun Aug 12, 2018 2:36 pm
Forum: software & utilities for the pc, mac or unix
Topic: Matrix Brandy BASIC V for Linux with SDL: V1.21.9 released
Replies: 175
Views: 2748

Re: Matrix Brandy BASIC V for Linux with SDL: V1.21.9 released

In the BBC environment, when the foreground application (eg BASIC) detects an Escape state it issues an EscapeAcknowledge OSBYTE &7E On Escape, yes, but unless it also happens on all untrapped errors it doesn't resolve this issue. When developing a program, especially, an error such as 'Mistake' or...
by jgharston
Sun Aug 12, 2018 12:09 am
Forum: software: other
Topic: 6502 RAM test.....
Replies: 1
Views: 141

Re: 6502 RAM test.....

Prime wrote:
Sat Aug 11, 2018 11:48 pm
Does anyone happen to have a routine to test RAM on a 6502, specifically an Acorn machine, source code would be wonderfull.
http://mdfs.net/Software/CommandSrc/Testing/
by jgharston
Sun Aug 12, 2018 12:05 am
Forum: software & utilities for the pc, mac or unix
Topic: Matrix Brandy BASIC V for Linux with SDL: V1.21.9 released
Replies: 175
Views: 2748

Re: Matrix Brandy BASIC V for Linux with SDL: V1.21.9 released

Edit 2: To enable communication of states across the boundary while maintaning a logical separation, I've gone ahead and implemented OSBYTE 42, currently only X=1 is supported to get or set the *Refresh state. I'm planning on just using A=42 and different X values if I want or need to pass other in...
by jgharston
Sat Aug 11, 2018 11:50 pm
Forum: software & utilities for the pc, mac or unix
Topic: Matrix Brandy BASIC V for Linux with SDL: V1.21.9 released
Replies: 175
Views: 2748

Re: Matrix Brandy BASIC V for Linux with SDL: V1.21.9 released

In the BBC environment, when the foreground application (eg BASIC) detects an Escape state it issues an EscapeAcknowledge OSBYTE &7E, and then it's down the the MOS to process whatever Escape Effects are in effect - flush sound queues, clear all buffers, turn EXEC off, cancel scroll pending, clear t...
by jgharston
Thu Aug 09, 2018 4:33 pm
Forum: software & utilities for the pc, mac or unix
Topic: Matrix Brandy BASIC V for Linux with SDL: V1.21.9 released
Replies: 175
Views: 2748

Re: Matrix Brandy BASIC V for Linux with SDL: V1.21.8 released

I've done some digging through the source for 1.50, and ignoring the TINT subcalls there is: COLOUR L -> VDU 17,L Select logical text colour L COLOUR L,P -> VDU 19,P,P<<8,P<<16,P<<24 Set logical colour L to physical colour P, allowing COLOUR L,&RRGGBBxx COLOUR R,G,B -> ColourTrans_SetTextColour,&00R...
by jgharston
Thu Aug 09, 2018 2:54 pm
Forum: software & utilities for the pc, mac or unix
Topic: Matrix Brandy BASIC V for Linux with SDL: V1.21.9 released
Replies: 175
Views: 2748

Re: Matrix Brandy BASIC V for Linux with SDL: V1.21.8 released

BASIC 1.16 in RISC OS 3.71 has both GCOL r,g,b and COLOUR r,g,b - and this: 10*SPOOL Test 20COLOUR12,34,56 30*SPOOL generates an empty file - no VDU codes are written to the file. Same is true testing GCOL12,34,56 What's the functionality of COLOUR a,b,c ? If it is COLOUR r,g,b what does it set to ...
by jgharston
Thu Aug 09, 2018 2:37 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 146
Views: 2185

Re: Z80 Protocol Decoder

Could be a red herring, but it could well be something floating on the bus when the interupt happens. The repeating instructions are "odd" in that they decrement the PC to do the repeat, that PC decrement could be related. Another thought, flags bit 5 and bit 3 are usually set to bit 5 and 3 of some...
by jgharston
Tue Aug 07, 2018 4:36 pm
Forum: general
Topic: Will it pop?
Replies: 12
Views: 305

Re: Will it pop?

@Jonathan - that looked horrible. I hope everything is now sorted and that you are okay now. Just had the follow-up appointment today. Biopsy is negative - "just a lump". Whoo hoo! I can have me hair cut. :) Though the operation revealed I've got high blood pressure (BP 187/106 resting), so I'm now...
by jgharston
Mon Aug 06, 2018 11:47 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 146
Views: 2185

Re: Z80 Protocol Decoder

It's just my Z80 Decoder that is mis-predicting the F5/F3 flags when an LDIR is interrupted, but so far only in this specific case. None of the flags should be changed by an interupt (unless the ISR messes with them). F is a full 8-bit register, every bit can hold a distinct state, it's not like th...
by jgharston
Mon Aug 06, 2018 11:27 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 146
Views: 2185

Re: Z80 Protocol Decoder

RESET does nothing to them, which from power on will most likely be random contents, and at other times will be whatever they happened to have... I think it's highly confusing to conflate 'reset' with 'power on'. By 'reset' I mean pulsing the reset pin of the chip, with no interruption of power. Wh...
by jgharston
Mon Aug 06, 2018 6:00 pm
Forum: programming
Topic: Teletext Paint Program
Replies: 6
Views: 426

Re: Teletext Paint Program

I will have another bash at trying to get your program working in Risc OS - I did try last time but I couldn't get very far ( after changing some paths ). See !ReadMe: Open the !Teletext application (Shift double-click) and load the TtxtInit file into a text editor, eg !Edit. a) Change Teletext$Dir...
by jgharston
Mon Aug 06, 2018 5:56 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 146
Views: 2185

Re: Z80 Protocol Decoder

60 LD A, &38 :\ value to be copied The semicolon comment delimiter, as listed by the OP, is accepted by BBC BASIC (Z80) isn't it? I have of course nabbed it as the 'line continuation' character in my more recent versions of BBC BASIC, so I prefer not to use it in the context of the assembler. And i...
by jgharston
Mon Aug 06, 2018 5:50 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 146
Views: 2185

Re: Z80 Protocol Decoder

It may be that some Z80s do (... clear all registers....), perhaps from specific manufacturers or of various design revisions, but the one I used in that device clearly didn't There could well be differences between different models/manufacturers. The documentation only states that RESET gives IR=0...
by jgharston
Mon Aug 06, 2018 5:29 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 146
Views: 2185

Re: Z80 Protocol Decoder

It may be that some Z80s do (... clear all registers....), perhaps from specific manufacturers or of various design revisions, but the one I used in that device clearly didn't There could well be differences between different models/manufacturers. The documentation only states that RESET gives IR=0...
by jgharston
Sun Aug 05, 2018 10:27 pm
Forum: programming
Topic: Teletext Paint Program
Replies: 6
Views: 426

Re: Teletext Paint Program

My teletext editor allows you to draw circles and simple lines. Not fully paint-style, but enough for simple stuff. The simpler solution might be to draw a picture in a normal graphics art program and then write some code to chunkify it into teletext characters.
by jgharston
Sun Aug 05, 2018 10:23 pm
Forum: general
Topic: Will it pop?
Replies: 12
Views: 305

Re: Will it pop?

Good to see you back. I'm tempted to change my avatar as well.

Before:
(throat - ick)
After:
(throat - ouch)
by jgharston
Sun Aug 05, 2018 10:01 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 146
Views: 2185

Re: Z80 Protocol Decoder

All resets always restart the CPU to address 0000. So I don't think there would be any need to monitor the reset pin. There may be as a RESET is subtly different from JP 0. JP 0 simply does PC=0 RESET does: all_registers=0 ie, AF/BC/DE/HL/AF'/BC'/DE'/HL'/IX/IY/SP/IR/IM/IFF/PC=0 (some documentation ...
by jgharston
Sat Aug 04, 2018 5:23 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 146
Views: 2185

Re: Z80 Protocol Decoder

One of the things I struggled with was recognising that an NMI was being handled, as there isn't any kind of explicit NMI acknowledge cycle indication. It was also interesting so see the ZX81 makes use of HALT. The simplest thing might be to just monitor the NMI line. The Z80 has an maskable interu...
by jgharston
Fri Aug 03, 2018 8:07 pm
Forum: software: other
Topic: BBC Font
Replies: 7
Views: 344

Re: BBC Font

* default 8-bit system fonts Interesting that there comes a point where people have concluded there are now enough dots available to go for a serif font, presumably thinking it will give a "professional" look and since the fashion has gone back to sans-serif fonts. Every now and then I *CLOAD merp ...
by jgharston
Fri Aug 03, 2018 8:00 pm
Forum: software & utilities for the pc, mac or unix
Topic: Matrix Brandy BASIC V for Linux with SDL: V1.21.9 released
Replies: 175
Views: 2748

Re: Matrix Brandy BASIC V for Linux with SDL

Jonathan, have you tried MUL on the PDP-11 Co Pro in either PiTubeDirect or the Matchbox? I check SIMH and E11 and they work, it's my implementation of MUL on PDPTube. I haven't checked the Matchbox as I can't get it to boot any more (mentioned elsewhere, a dry solder pad or loose connection was su...
by jgharston
Fri Aug 03, 2018 7:53 pm
Forum: software: other
Topic: CPMFiler
Replies: 3
Views: 210

Re: CPMFiler

If I try to MOUNT a .dsd image, I get a garbled display and cannot see the files. Any suggestion on what I'm doing wrong please? Mounting a DSD image. AcornCPM, like all 8-bit Acorn filing systems, is a sequential disk system, it uses all of one side of the disk followed by all of the other side of...
by jgharston
Fri Aug 03, 2018 7:51 pm
Forum: programming
Topic: Beeb ENVELOPE documentation
Replies: 4
Views: 151

Re: Beeb ENVELOPE documentation

The diagram in the user guide is telling me that you can have two equal sections by making two of the three sections the same length and one of them twice as long, so you get, eg: 1+1+2 which gives you 2+2. It gives an example of a police siren, presumably going WEE wah WEE wah WEE wah.