Search found 1330 matches

by Rich Talbot-Watkins
Mon Oct 08, 2018 2:05 am
Forum: bbcmicro.co.uk
Topic: Game information - help required
Replies: 18
Views: 472

Re: Game information - help required

Yeah actually I'd love to know where Crazy Balloon came from originally. Someone must know.

(Maybe Dave M knows where he got the original disk image from? Eventually these things have to trace back to their source!)
by Rich Talbot-Watkins
Fri Oct 05, 2018 12:37 pm
Forum: hardware
Topic: VDU5 behaves differently on Model B vs. Master
Replies: 30
Views: 636

Re: VDU5 behaves differently on Model B vs. Master

Coeus wrote:
Fri Oct 05, 2018 11:40 am
To have got as far as producing a masked ROM and for it then to be rare in the wild suggests a serious bug. Any idea what is was?
The cassette one which corrupted saved files (which required a dummy byte in the leader tone)? Or was that a 0.10 bug fixed by 1.00?
by Rich Talbot-Watkins
Fri Oct 05, 2018 12:36 pm
Forum: hardware
Topic: VDU5 behaves differently on Model B vs. Master
Replies: 30
Views: 636

Re: VDU5 behaves differently on Model B vs. Master

"This is some text" would appear at graphics co-ordinates 100,100 and "This is some more text" would appear at text co-ordinates 4,5. In other words even while VDU 5 is in effect I would expect VDU codes that are documented as moving the text cursor to do exactly that but then when printable charac...
by Rich Talbot-Watkins
Thu Oct 04, 2018 5:24 pm
Forum: hardware
Topic: VDU5 behaves differently on Model B vs. Master
Replies: 30
Views: 636

Re: VDU5 behaves differently on Model B vs. Master

It's definitely very curious. It'd be interesting to know what the rationale for removing it was, because, as you say, it was a breaking change from 0.10 to 1.00, and it doesn't really seem like a bad feature. My thoughts are: * For clarity: it's easier to state that TAB(x,y) is for the text cursor ...
by Rich Talbot-Watkins
Thu Oct 04, 2018 3:27 pm
Forum: hardware
Topic: VDU5 behaves differently on Model B vs. Master
Replies: 30
Views: 636

Re: VDU5 behaves differently on Model B vs. Master

"This command has now been implemented" sounds to me like something which was proactively done, as opposed to "this behaviour changed" which sounds like documenting something which may or may not have occurred by accident. That was my take anyway. Possibly we're looking at this from two different pe...
by Rich Talbot-Watkins
Thu Oct 04, 2018 2:30 pm
Forum: hardware
Topic: 65c02 in a Model B
Replies: 13
Views: 583

Re: 65c02 in a Model B

The Oric has weird clock requirements as the ULA requires 2 RAM accesses for every CPU RAM access (it has to read a bye from video memory, and then look up its pixel definition, Teletext-style).
by Rich Talbot-Watkins
Thu Oct 04, 2018 12:59 pm
Forum: hardware
Topic: VDU5 behaves differently on Model B vs. Master
Replies: 30
Views: 636

Re: VDU5 behaves differently on Model B vs. Master

Aha! http://chrisacorns.computinghistory.org.uk/docs/Acorn/AN/036.pdf Support Group Application Note 36 Master 128 Welcome Disc "Converter" Program l) On OS 1.20, the TAB(X,Y) vdu sequence has no effect while in VDU 5 mode. On the Master Series this command has now been implemented in this mode, to ...
by Rich Talbot-Watkins
Thu Oct 04, 2018 9:12 am
Forum: hardware
Topic: VDU5 behaves differently on Model B vs. Master
Replies: 30
Views: 636

Re: VDU5 behaves differently on Model B vs. Master

I do not believe that is correct. In every OS version I've tried, and in RISC OS, Brandy, BB4W and BBCSDL, VDU 5,30 moves the graphics cursor to the top left, not the bottom left, of the graphics viewport. Yes, my apologies, you're right (just tried in jsbeeb). I guess I was remembering the fact th...
by Rich Talbot-Watkins
Thu Oct 04, 2018 8:19 am
Forum: hardware
Topic: VDU5 behaves differently on Model B vs. Master
Replies: 30
Views: 636

Re: VDU5 behaves differently on Model B vs. Master

Comparing disassemblies, OS 1.20 does this: ;0322 = supplied X coordinate ;0323 = supplied Y coordinate C787 JSR &C588 ;A=0 if text cursor A=&20 if graphics cursor C78A BNE &C758 ;exit C78C JSR &C7A8 ;exchange text column/line with workspace 0328/9 C78F CLC ;clear carry C790 LDA &0322 ;get X coordin...
by Rich Talbot-Watkins
Wed Oct 03, 2018 8:26 pm
Forum: hardware
Topic: VDU5 behaves differently on Model B vs. Master
Replies: 30
Views: 636

Re: VDU5 behaves differently on Model B vs. Master

This observation was made by Richard Toohey here , when looking at OS 0.1 games which didn't run on OS 1.20. It was the first time I'd heard about it. The OS 1.20 approach feels like the right one, but I'd assume it was a deliberate choice to reinstate the old behaviour in the Master OS (as it would...
by Rich Talbot-Watkins
Tue Oct 02, 2018 1:54 pm
Forum: hardware
Topic: 65c02 in a Model B
Replies: 13
Views: 583

Re: 65c02 in a Model B

The early Acornsoft disk protection systems used undocumented opcodes, as does Zalaga. The tape protection on Nightshade and Lunar Jetman won't work because of the timing difference for JMP (indirect). I can't think of any other issues for the moment though.
by Rich Talbot-Watkins
Mon Oct 01, 2018 9:05 am
Forum: software & utilities for the pc, mac or unix
Topic: Matrix Brandy BASIC V for Linux with SDL: V1.21.15 released
Replies: 317
Views: 8909

Re: Matrix Brandy BASIC V for Linux with SDL: V1.21.14 released

The hostility of some of the RISC OS community is one of the reasons I turned my back on it. Sorry that you had to get involved in that :(
by Rich Talbot-Watkins
Mon Sep 24, 2018 5:52 pm
Forum: software: classic games
Topic: Unused Citadel bits
Replies: 48
Views: 4559

Re: Unused Citadel bits

Citadel uses a reduced height screen, using just the last 20 or so rows of a standard MODE 2 screen, and is then recentred vertically. So I think what you have there looks correct!
by Rich Talbot-Watkins
Fri Sep 21, 2018 8:02 pm
Forum: general
Topic: Does anyone 'own' SSD and DSD
Replies: 21
Views: 484

Re: Does anyone 'own' SSD and DSD

The problem with these formats is that they are literally just a sector dump with no metadata or versioning, or anything which can readily help to identify their validity. In fact the extension is the only thing which really identifies them at all, and the only thing which can distinguish a single s...
by Rich Talbot-Watkins
Fri Sep 21, 2018 7:52 pm
Forum: projects
Topic: Exile Map Editor
Replies: 3
Views: 167

Re: Exile Map Editor

Superb! Looking forward to playing with this!
by Rich Talbot-Watkins
Fri Sep 21, 2018 11:11 am
Forum: general
Topic: Best Basic Games
Replies: 11
Views: 365

Re: Best Basic Games

I think the Beeb 'suffered' this more than most other platforms though, because BBC BASIC was so much faster and better than BASICs on other machines. I'd be incredibly surprised, for example, to find commercial games written in BASIC on the Spectrum beyond the first few months of its release, becau...
by Rich Talbot-Watkins
Thu Sep 20, 2018 8:19 pm
Forum: other vintage computer hardware, software and games
Topic: Trying to track down an old Programmer - Steve Sutton
Replies: 6
Views: 417

Re: Trying to track down an old Programmer - Steve Sutton

Way too young I think, I've tried a few on linkedin, but I think since we are talking mid 60's onwards, age wise, they could be well retired :) Ah I forgot to mention, age wise I think it could be mid 60's onwards. Ah... I figured that the chap I came across finished university in 1984, which was m...
by Rich Talbot-Watkins
Thu Sep 20, 2018 9:00 am
Forum: general
Topic: Best Basic Games
Replies: 11
Views: 365

Re: Best Basic Games

Plankwalk
Image

All Basic apart from the monster logic. And it unironically remains one of my favourite games on the Beeb to this day!
by Rich Talbot-Watkins
Wed Sep 19, 2018 11:58 am
Forum: other vintage computer hardware, software and games
Topic: Trying to track down an old Programmer - Steve Sutton
Replies: 6
Views: 417

Re: Trying to track down an old Programmer - Steve Sutton

Long shot, but... https://www.linkedin.com/in/steve-sutton-10236320 ? Name, age and location seem to coincide, but I suspect it's coincidence. The QL work would've had to be as a side-project rather than a full-time job. Edit: His first listed job includes "Large Civil & Defense Systems, Banking, Go...
by Rich Talbot-Watkins
Wed Sep 19, 2018 7:17 am
Forum: programming
Topic: Beeb Shadow RAM, load image from disc?
Replies: 12
Views: 347

Re: Beeb Shadow RAM, load image from disc?

A final word of caution. If you're doing this from BASIC, ensure that the program line is located below &3000 in memory, otherwise the *FX108,1 will page out the BASIC program!
by Rich Talbot-Watkins
Mon Sep 17, 2018 9:38 pm
Forum: projects
Topic: 160 x 128 mode
Replies: 21
Views: 492

Re: 160 x 128 mode

What is this witchcraft!!! So you mean that only every other scanline gets an hsync? I'd never have expected that to work, but how cool that it does! I guess composite needs the colour burst and whatever at the beginning of each line, and without it bad things happen. What happens if you turn on int...
by Rich Talbot-Watkins
Sat Sep 15, 2018 5:27 pm
Forum: projects
Topic: Interlace stuff
Replies: 12
Views: 384

Re: Interlace stuff

B-Em can be coaxed into displaying it in the same way as jsbeeb by selecting Settings -> Video -> Display type -> Interlaced. It's really hard to know how to display a 50Hz emulated screen on a PC with an arbitrary monitor refresh rate. If you don't mind the latency, you can run a frame in advance a...
by Rich Talbot-Watkins
Fri Sep 14, 2018 3:18 pm
Forum: projects
Topic: Interlace stuff
Replies: 12
Views: 384

Re: Interlace stuff

That would require a vertical rupture type technique, but I'm uncertain whether that even works in interlaced modes; it depends whether the crtc uses R4 or R7 to determine when to toggle the field type. It would work if it were the latter.
by Rich Talbot-Watkins
Fri Sep 14, 2018 9:41 am
Forum: projects
Topic: Interlace stuff
Replies: 12
Views: 384

Re: Interlace stuff

It can if you toggle between each screen bank on each field. I remember the Acorn User article, on my monitor it flickered unacceptably. I'll see if I can find it. Yeah, I guess if you get the timing perfect, and switch displayed bank just before line 128 is rasterised, you could do it. You'd have ...
by Rich Talbot-Watkins
Fri Sep 14, 2018 9:21 am
Forum: projects
Topic: Interlace stuff
Replies: 12
Views: 384

Re: Interlace stuff

And the interlaced sync and video mode can be used to ensure the even field reads even addresses, and the odd field (which is offset by half a scanline) reads odd addresses, thus avoiding the problem with the fields being out of sync with the rendering. The only problem is you have to use the Beeb's...
by Rich Talbot-Watkins
Wed Sep 12, 2018 9:00 am
Forum: other vintage computer hardware, software and games
Topic: Acorn games on other platforms
Replies: 16
Views: 515

Re: Acorn games on other platforms

And of course Repton 1 & 2 got a release as Repton Mania on the Spectrum later on. By Fair Means or Foul got a simultaneous release on multiple platforms, but it's probably safe to state that it originated on the Beeb, it being a Superior Software production. I think The Sentinel and Cholo were also...
by Rich Talbot-Watkins
Wed Sep 12, 2018 8:57 am
Forum: other vintage computer hardware, software and games
Topic: Acorn games on other platforms
Replies: 16
Views: 515

Re: Acorn games on other platforms

Thrust also started life on the Beeb, and was then ported to C64, CPC, Atari and Speccy while they worked on an Electron version. The C64 version was then released before the Beeb/Electron versions.
by Rich Talbot-Watkins
Tue Sep 11, 2018 9:39 am
Forum: hardware
Topic: NMI/IRQ timing to vector pull
Replies: 22
Views: 588

Re: NMI/IRQ timing to vector pull

Thanks for checking it out Dave. It's nice to have this confirmed (according to that jsbeeb github thread, I already had a hunch about it a couple of years ago). Not sure how you're arriving at minimum 1 cycle latency for interrupts, but we can continue that discussion on 6502.org!
by Rich Talbot-Watkins
Thu Sep 06, 2018 9:27 am
Forum: hardware
Topic: NMI/IRQ timing to vector pull
Replies: 22
Views: 588

Re: NMI/IRQ timing to vector pull

I'm going to stick my neck out and claim that CMOS 6502 don't have the special interrupt behaviour on branches. Here's the jsbeeb change I was alluding to earlier: https://github.com/mattgodbolt/jsbeeb/commit/f65a02d1677ba42ddddb50fd7847a6549a0bb5c8 and the bug thread about it: https://github.com/ma...
by Rich Talbot-Watkins
Wed Sep 05, 2018 5:26 pm
Forum: hardware
Topic: NMI/IRQ timing to vector pull
Replies: 22
Views: 588

Re: NMI/IRQ timing to vector pull

I think this example is more like the one in the trace (with respect to the IRQ signal timing): http://visual6502.org/JSSim/expert.html?graphics=false&steps=33&r=fd&a=fd&d=58a900f000a95ceaea&irq0=11&logmore=sync,irq,480,D1x1 I've added signal 480, which is derived from the irq signal in the previous...