Search found 168 matches

by joachim
Sat Jun 20, 2020 9:37 pm
Forum: 32-bit acorn software: other
Topic: Acorn Virus in the early 90’s
Replies: 7
Views: 456

Re: Acorn Virus in the early 90’s

According to the Archimedes Virus Reference Document (http://www.bogus.net/~torh/files/AVRD-1.91t.txt, other copies also findable on Google), you're most likely referring to a virus called "Module" or "ModVir": Module =========================================================================== Last U...
by joachim
Thu Jun 18, 2020 2:27 pm
Forum: other vintage hardware, software and languages
Topic: Papercraft models of 80s computers
Replies: 6
Views: 675

Re: Papercraft models of 80s computers

Interesting that the Repton 2 screenshot is of the early/prerelease edition in which Screen A is red rather than blue. (Repton 2 colours thread)
by joachim
Wed Jun 10, 2020 10:59 pm
Forum: scanning of books, magazines, ads and letters
Topic: Personal Computer World scans!
Replies: 58
Views: 1836

Re: Personal Computer World scans!

Out of interest, which is the earliest PCW magazine to feature the BBC Micro ? That would be December 1981: https://archive.org/details/PersonalComputerWorld1981-12/mode/2up Seriously, though, I'd hang about until they've all finished deriving the "PDF with Text" versions. The initial PDFs are gian...
by joachim
Tue Jun 09, 2020 9:51 am
Forum: 8-bit acorn software: classic games
Topic: Dunjunz reminiscing and walkthrough
Replies: 5
Views: 562

Re: Dunjunz reminiscing and walkthrough

What would it take to get the new levels hosted on bbcmicro.co.uk?
by joachim
Mon Jun 01, 2020 3:47 pm
Forum: programming
Topic: Reducing Basic Program Size
Replies: 34
Views: 1926

Re: Reducing Basic Program Size

One way programs can use space unnecessarily is having two copies of things in memory: one copy in a program statement defining it, and another copy in its intended location in memory. As you mentioned, the classic example is DATA statements - the data exists twice, in the DATA statements themselve...
by joachim
Sun May 31, 2020 12:32 pm
Forum: programming
Topic: Adding in negative numbers
Replies: 12
Views: 332

Re: Adding in negative numbers

LDA&81 ; bytes 2 cycles 3 TAX; CLC ; bytes 1 cycles 2 ADC&86 bytes 2 cycles 3 STA&81 ; bytes 2 cycles 3 BCC done ; bytes 2 cycle 2/3 TXA BMI dechighbyte INC &82; bytes 2 cycles 5 BNE done .dechighbyte DEC &82 ; bytes 2 cycles 5 .done In the negative-offset case, that code DECs when the carry is set...
by joachim
Sun May 31, 2020 9:09 am
Forum: programming
Topic: Adding in negative numbers
Replies: 12
Views: 332

Re: Adding in negative numbers

I found code examples here: https://codebase64.org/doku.php?id=base:signed_8bit_16bit_addition It seems you cannot do better than to calculate the high byte and ADC it. (The alternative would be to have a branch with INC and a branch with DEC and to determine explicitly which of four cases you're in...
by joachim
Sat May 30, 2020 4:58 pm
Forum: 8-bit acorn software: classic games
Topic: Dunjunz reminiscing and walkthrough
Replies: 5
Views: 562

Re: Dunjunz reminiscing and walkthrough

Recently? Your playthroughs inspired this interesting forum thread back in 2016!
by joachim
Wed May 27, 2020 7:49 pm
Forum: scanning of books, magazines, ads and letters
Topic: Personal Computer World scans!
Replies: 58
Views: 1836

Re: Personal Computer World scans!

I believe there are quite a few Acorn program listings in PCW that have yet to be archived (see for example https://ukfree.tv/documents/pcw/#Programs).
by joachim
Thu Apr 30, 2020 10:56 am
Forum: 8-bit acorn software: classic games
Topic: Repton 3: Emulator/RNG issue
Replies: 76
Views: 3444

Re: Repton 3: Emulator/RNG issue

&2F01/&2F01: LDA &31A0,X / LDA #&C sequence replaced with CPY #&A0 / AND (&A9),Y / ASL A; purpose unknown ^^ took another look at this, and decided it was probably data and not code; certainly "JSR &A25C" just above it makes very little sense Looks as if you decompiled with the wrong frame. JSR &A2...
by joachim
Wed Oct 09, 2019 11:04 pm
Forum: 8-bit acorn software: classic games
Topic: Firebug, Sorcery, Boxer and Smash and Grab...
Replies: 6
Views: 583

Re: Firebug, Sorcery, Boxer and Smash and Grab...

More likely that it's just the same basic engine recycled for each game. Other examples of this include Rally Driver / Slippery Sam by Anthony Houghton, Southern Belle / Evening Star by Male and Hillyer, and on the Sinclair QL, Metropolis / Citadel by Janko Mršić-Flögel. Plus of course the explicit...
by joachim
Thu Sep 26, 2019 9:15 pm
Forum: 8-bit acorn hardware
Topic: Problems booting beeb issue 4
Replies: 73
Views: 4101

Re: Problems booting beeb issue 4

In summary, there's no smoking gun here. On the software side, the VARTOP value you obtained matches what my working machine gives. The question is what values is your machine checking against VARTOP... You would expect MODEs 4 and 5 to fail in a 16k machine with DFS (which is the configuration in ...
by joachim
Sun Jul 07, 2019 6:40 pm
Forum: 8-bit acorn software: other
Topic: Basic BASIC Question
Replies: 28
Views: 1406

Re: Basic BASIC Question

And for some reason, people seemed to mostly use 224-255 to refer to them... I investigated this a while ago. The User Guide recommends use of the range 224–225 in chapters 29 and 34, and presumably most people's practices ultimately derive from that. Also, on OS 0.10 , 224–255 are the values retur...
by joachim
Tue Jun 04, 2019 3:59 pm
Forum: 8-bit acorn software: classic games
Topic: Acorn Electron Games that don't work with a plus 1 ?
Replies: 11
Views: 1049

Re: Acorn Electron Games that don't work with a plus 1 ?

Line 30 looks a bit suspicious. I think it should read something like:

30 !&80=USR&FFF4:A%=!&81:A%?12=0
by joachim
Wed Apr 24, 2019 8:36 pm
Forum: 8-bit acorn software: other
Topic: Drawing a circle in BBC BASIC
Replies: 66
Views: 5780

Re: Drawing a circle in BBC BASIC

Logically, if anybody implemented ellipse arcs, sectors, and segments, those are the plot numbers that should be used. Interesting. Have you given any thought to how elliptical arcs, sectors and segments would be specified using only three points (I presume it's a fundamental characteristic of VDU ...
by joachim
Mon Apr 15, 2019 11:21 pm
Forum: other vintage hardware, software and languages
Topic: Interesting treasures in shops near you?
Replies: 3
Views: 613

Re: Interesting treasures in shops near you?

Well, there's a couple of classic machines in this window: https://goo.gl/maps/LjgQ6qSTiy42. Is that the sort of thing you had in mind?
by joachim
Wed Feb 27, 2019 9:35 pm
Forum: archive requests
Topic: The Micro User 1991/1992; Let's Compute Game articles..
Replies: 4
Views: 593

Re: The Micro User 1991/1992; Let's Compute Game articles..

I dumped all the Electron user cassettes back in 2001/2003: http://www.stairwaytohell.com/electron/uefarchive/magtapes/ElectronUser/ Though Mick, Lee and team may well have already gone through these already ... I asked about the (lack of) Electron User games on bbcmicro.co.uk just over a year ago:...
by joachim
Fri Feb 22, 2019 8:46 pm
Forum: for sale / freebies
Topic: Free to collector Archimedes swag
Replies: 26
Views: 2538

Re: Free to collector

Agreed those are 128kB roms. The type numbers (531000, 831000, 231024) end in "1000" or "1024" most likely signifying 1Mbit = 128kB, and Google search for those numbers and "rom" appears to confirm that. (Also, here are some people talking about dumping similar 128kB roms using an EPROM programmer: ...
by joachim
Wed Jan 30, 2019 4:10 am
Forum: general
Topic: Old Usbourne books, free PDFs from Usbourne!
Replies: 30
Views: 4361

Re: Old Usbourne books, free PDFs from Usbourne!

Okay, here is the type-in. I tested it a little in RPCemu (of all things), so it should be free from typos ... but I don't have it as an .ssd image so I'm just attaching it as text (as formatted by !Edit). (I fixed at least two vital typos in the printed listing, too: line 200 and line 650. Now I'm ...
by joachim
Tue Jan 29, 2019 5:01 pm
Forum: general
Topic: Old Usbourne books, free PDFs from Usbourne!
Replies: 30
Views: 4361

Re: Old Usbourne books, free PDFs from Usbourne!

It's an awful font for listings, too, but I think they're readable if you enlarge them to full size and apply a little skill and judgement. I could type it in myself if you like, although I may or may not be able to rig up the technology to tokenize and test a BASIC listing and transfer the result t...
by joachim
Tue Jan 29, 2019 5:33 am
Forum: general
Topic: Old Usbourne books, free PDFs from Usbourne!
Replies: 30
Views: 4361

Re: Old Usbourne books, free PDFs from Usbourne!

Another Usborne book was "Understanding Computer Graphics" by Judy Tatchell and Les Howarth, and it includes a game, "Bouncing Bug", which would merit a place on bbcmicro.co.uk. I don't know why this particular book is not available on the Usborne PDF download page, but I just happen to have scans o...
by joachim
Sun Dec 16, 2018 3:37 am
Forum: 8-bit acorn software: classic games
Topic: Deathstar "inbuilt cheat"
Replies: 0
Views: 554

Deathstar "inbuilt cheat"

Micro User and Electron User respectively published cheat keys for the BBC and Electron versions of Deathstar. Copied here from the STH cheats page : [BBC version] If you press Caps Lock + Control + Escape you will be promoted to the next level. You still have your current quota of starbombs, but th...
by joachim
Sat Oct 20, 2018 3:07 am
Forum: general
Topic: Best Basic Games
Replies: 12
Views: 1125

Re: Best Basic Games

Manic Mole is one of the first BBC/Electron games I ever had so I could be biased, but it's an all-Basic platformer that runs very nicely. Possibly the only game that manages to run at a playable speed in VDU 5 mode …
by joachim
Sun Oct 14, 2018 10:52 am
Forum: the complete BBC games archive
Topic: Game information - help required
Replies: 23
Views: 2680

Re: Game information - help required

Gladiator displays "(C) BEEBUG" when it starts. And the listing of Sea Battle contains the notice "(C) YOUR COMPUTER". And the loader for Millipede has an Acornsoft copyright notice (unless you think it's another fake like Crazy Balloon). And the listing of "Caves of Trall" contains some comments in...
by joachim
Sun Oct 14, 2018 10:17 am
Forum: 8-bit acorn software: classic games
Topic: Favourite/best games list
Replies: 88
Views: 20829

Re: Favourite/best games list

Top ten: Elite Dunjunz Ricochet (I can't believe this isn't in anyone's list) Exile Imogen Repton 3 Citadel Repton Infinity Jet Set Willy Thrust The next dozen: (because it was so hard to choose) Galaforce 2, Galaforce, Bonecruncher, Repton, The Sentinel, Spycat, XOR, Inertia, Ravenskull, Pipeline,...
by joachim
Sat Oct 13, 2018 8:01 pm
Forum: 32-bit acorn software: other
Topic: Combining sprites in RiscOS
Replies: 4
Views: 811

Re: Combining sprites in RiscOS

Just in case anyone wants to construct a general solution, the sprite file format is (obliquely) documented in the PRMs at http://www.riscos.com/support/developers/prm/sprites.html. (Note in "Technical Details", the sentence "The format of the file created by a *ScreenSave or *SSave command is the s...
by joachim
Fri Oct 12, 2018 11:31 pm
Forum: programming
Topic: The book of listings -Numbfinger
Replies: 7
Views: 807

Re: The book of listings -Numbfinger

well, I will be deciphering that one a bit further down the line. It actually just calls *FX 122 in a loop until it gets back the value 255. It looks scary because although Acorn provided *FX as a friendly way of making OS calls, they didn't provide any nice way of reading the result of an OS call ...
by joachim
Fri Oct 12, 2018 5:25 pm
Forum: programming
Topic: The book of listings -Numbfinger
Replies: 7
Views: 807

Re: The book of listings -Numbfinger

Right, now I look at the whole listing I agree with you: line 230 to ignore previous input is OK but line 240 is getting a keypress and throwing it away, which is obviously wrong at this point in the program. (My line 240 above also does that, because I didn't look at the context.) If I were writing...
by joachim
Thu Oct 11, 2018 8:42 pm
Forum: programming
Topic: The book of listings -Numbfinger
Replies: 7
Views: 807

Re: The book of listings -Numbfinger

240 waits for a key to be pressed before advancing. 230 is supposed to make sure that the user doesn't accidentally advance due to either (i) having a key already held down when line 240 is reached or (ii) having previously pressed a key which is still in the keyboard buffer. I think preventing (i) ...

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