Search found 1128 matches

by Rich Talbot-Watkins
Wed Jan 17, 2018 8:13 pm
Forum: software: other
Topic: ASBAS Assembly Orientated BASIC
Replies: 5
Views: 157

Re: ASBAS Assembly Orientated BASIC

Wouldn't have really been useful for me - I used to use SIN/COS/SQR etc all the time for building tables and so on. In fact, that was one of my main reasons for writing BeebAsm in the first place - to have a 6502 cross assembler that could let me use these functions to build tables within my assembl...
by Rich Talbot-Watkins
Mon Jan 15, 2018 5:00 pm
Forum: programming
Topic: Many DEFPROC, 1 ENDPROC?
Replies: 17
Views: 1025

Re: Many DEFPROC, 1 ENDPROC?

If you want the compiler to be able to work out that it's safe to lift a strlen call out of a loop, you need it to know two things: ⋅ strlen() is a pure function (it has absolutely no side effects; it's impossible to tell if you called it once or twice) ⋅ The string its argument...
by Rich Talbot-Watkins
Mon Jan 15, 2018 2:30 pm
Forum: programming
Topic: 32k memory management for dummies
Replies: 28
Views: 747

Re: 32k memory management for dummies

OS 0.1 had *NOTAPE, which I assume deselected the filing system. Presumably they considered it useless enough to remove!
by Rich Talbot-Watkins
Mon Jan 15, 2018 2:21 pm
Forum: programming
Topic: Many DEFPROC, 1 ENDPROC?
Replies: 17
Views: 1025

Re: Many DEFPROC, 1 ENDPROC?

Of course, in this example, you'd be even better just writing: for (i = 0; s[i] != 0; i++) { x = s[i]; ... } to save iterating through the string twice (once in strlen, once in the loop). Edit: I previously stated that the compiler could be clever enough to hoist the strlen out of the loop if it mee...
by Rich Talbot-Watkins
Mon Jan 15, 2018 8:19 am
Forum: programming
Topic: BeebAsm's Hello World - printing part of file name, not "Hello World"
Replies: 12
Views: 249

Re: BeebAsm's Hello World - printing part of file name, not "Hello World"

tom_seddon wrote:I keep putting off thinking about this, but github sent me an email about the new PR, so I suppose I just have to admit it: I've been a terrible steward of this project :(

Not as bad as me! :lol:
by Rich Talbot-Watkins
Sun Jan 14, 2018 9:33 pm
Forum: programming
Topic: BeebAsm's Hello World - printing part of file name, not "Hello World"
Replies: 12
Views: 249

Re: BeebAsm's Hello World - printing part of file name, not "Hello World"

Erm, oops, yeah... my bad. I clearly wrote that help text as quickly as I wrote the initial release of BeebAsm. Sorry about that. Dunno who maintains the BeebAsm repo these days, but yeah feel free to get that changed. I guess I never expected anyone to ever try to assemble that (it was more of a &q...
by Rich Talbot-Watkins
Fri Jan 12, 2018 4:14 pm
Forum: software: other
Topic: Adventure games: written in assembler? What compression?
Replies: 6
Views: 292

Re: Adventure games: written in assembler? What compression?

You might be interested in the articles in Acorn User August and September 1988 on the adventure "The Warlord". The September article goes into some details about the engine it used (TAG), including examples of its scripting language and text compression techniques.
by Rich Talbot-Watkins
Fri Jan 12, 2018 2:40 pm
Forum: software: classic games
Topic: Citadel Item Randomiser 0.1 (and now 0.2)
Replies: 28
Views: 966

Re: Citadel Item Randomiser 0.1 (and now 0.2)

I just tried it: I replaced all the STA &359 with STA &36D and disabled the Master patch. Result? Hangs like the original version. So then I patched that LDA #&0E:STA &308 with LDA #0, and it no longer hangs, so that was the main problem. I have no idea why it was originally doing th...
by Rich Talbot-Watkins
Fri Jan 12, 2018 2:12 pm
Forum: software: classic games
Topic: Citadel Item Randomiser 0.1 (and now 0.2)
Replies: 28
Views: 966

Re: Citadel Item Randomiser 0.1 (and now 0.2)

Incidentally, that weird code in the patch which is checking for certain magic values and converting them to other magic values: that's translating a 'stripy' colour value into the best flat colour that can be selected using a legal GCOL call. That's why stuff like the Witch's House roof looks flat ...
by Rich Talbot-Watkins
Fri Jan 12, 2018 1:47 pm
Forum: software: classic games
Topic: Citadel Item Randomiser 0.1 (and now 0.2)
Replies: 28
Views: 966

Re: Citadel Item Randomiser 0.1 (and now 0.2)

Yes, I also just had a look at it. Seems like, on the Master, VDU variable &359 moved to &36D. On the Master &359 is "0 if plotting graphics foreground, 8 if plotting graphics background" - seems like any other value can make it hang completely! So they just replaced those writ...
by Rich Talbot-Watkins
Fri Jan 12, 2018 11:53 am
Forum: software: classic games
Topic: Citadel Item Randomiser 0.1 (and now 0.2)
Replies: 28
Views: 966

Re: Citadel Item Randomiser 0.1 (and now 0.2)

Here's the 2 file (CITADEL and CITAX), no speech, no title screen, PIAS1 re-release BBC Master compatible disk version, which I guess would've been the last official release of the game :?: (CHAIN"CITADEL" to load!) There will in fact have been another version, as that's not Master Compac...
by Rich Talbot-Watkins
Fri Jan 12, 2018 11:40 am
Forum: software: classic games
Topic: Citadel Item Randomiser 0.1 (and now 0.2)
Replies: 28
Views: 966

Re: Citadel Item Randomiser 0.1 (and now 0.2)

Just to further muddy the waters, in both the FDI and FSD 5681: lda #$01 5683: sta $54cf 5686: rts And in the original FDI we have: 54C5 LDA #&59 54C7 STA &06 54C9 LDA &1300,Y 54CC STY &01 54CE EOR &06 <-- self modified to EOR &01 by that code 54D0 STA &0400,Y 54D3 EOR &...
by Rich Talbot-Watkins
Fri Jan 12, 2018 10:05 am
Forum: software: classic games
Topic: Citadel Item Randomiser 0.1 (and now 0.2)
Replies: 28
Views: 966

Re: Citadel Item Randomiser 0.1 (and now 0.2)

Here's the .fdi image for the original disk release of Citadel I was using, by the way. Use B-Em to load it.
by Rich Talbot-Watkins
Fri Jan 12, 2018 10:02 am
Forum: software: classic games
Topic: Citadel Item Randomiser 0.1 (and now 0.2)
Replies: 28
Views: 966

Re: Citadel Item Randomiser 0.1 (and now 0.2)

Well, none of the STH images are originals, because the SSD format can't support protected disks. So all of those images are necessarily versions which have had their protection stripped and put onto a clean DFS format disk image. The Citadel.ssd file on STH appears to be direct rip from tape of the...
by Rich Talbot-Watkins
Fri Jan 12, 2018 8:59 am
Forum: software: classic games
Topic: Citadel Item Randomiser 0.1 (and now 0.2)
Replies: 28
Views: 966

Re: Citadel Item Randomiser 0.1 (and now 0.2)

I just took a look at the original disk release. CITAL is a strange bit of code: in place of the NOPs there's a bunch of code which (after loading CITAM), reads the catalog info for CITAM, and then loads it again at its natural location. *INFO for CITAM looks like this: $.CITAM 008000 00A670 004100 ...
by Rich Talbot-Watkins
Fri Jan 12, 2018 8:29 am
Forum: software: classic games
Topic: Citadel Item Randomiser 0.1 (and now 0.2)
Replies: 28
Views: 966

Re: Citadel Item Randomiser 0.1 (and now 0.2)

This looks like a transfer from tape ("Press Play" in the loader), and is a Master-compatible version, which means it contains the patch to move some code to Sideways RAM bank 5. I'm fairly sure that those NOPs are in the released version (I remember also being baffled by them when transfe...
by Rich Talbot-Watkins
Sat Jan 06, 2018 10:03 am
Forum: software: other
Topic: Tape protection systems
Replies: 67
Views: 5649

Re: Tape protection systems

Ahh hahaha, I forgot IRQ2V even existed! Don't think I ever used it in my life!

So, if the uef.hq has preserved the data correctly, the question is: what is it about the data which is not reading correctly in BeebEm, B-Em or jsbeeb? And have you figured out the basic mechanism of the protection?
by Rich Talbot-Watkins
Fri Jan 05, 2018 3:19 pm
Forum: software: other
Topic: Tape protection systems
Replies: 67
Views: 5649

Re: Tape protection systems

Yeah that's weird. The .hq.uef image from the old Acorn Preservation site is getting stuck after running ABBEY2 in the following place: 055f LDA #&00 0561 STA &76 0563 LDA &76 <-- 0565 BEQ &0563 <-- 0567 LDA #&00 0569 STA &76 No idea what is supposed to be changing &76 as...
by Rich Talbot-Watkins
Thu Jan 04, 2018 11:59 am
Forum: projects
Topic: New game - tube type thingy
Replies: 28
Views: 905

Re: New game - tube type thingy

Wow, what a fantastic idea - totally original, and the only thing which vaguely compares are those palette switching 'through the tunnel' demos, like Orlando's 3D Wars. This is of course far better, and I think it's fair to say that it's the first time I've seen perspective correct texturing on the ...
by Rich Talbot-Watkins
Sun Dec 31, 2017 2:58 pm
Forum: software: classic games
Topic: Unused Citadel bits
Replies: 42
Views: 1731

Re: Unused Citadel bits

Yeah, the screenshots I added upthread show that. The reason for it is that, for some reason, the triangle coordinates which make the roof are slightly off (the two bottom y coordinates are not equal). OS 1.20 has a small bug where triangles aren't plotted correctly in this case (it just plots the f...
by Rich Talbot-Watkins
Thu Dec 21, 2017 8:39 pm
Forum: software: classic games
Topic: Repton Infinity High Score Anagrams
Replies: 22
Views: 2642

Re: Repton Infinity High Score Anagrams

Codename Druid from Acorn User is another game by Daves Lawrence and Acton (credited to "Chris Ruseman"). And the high score name is LEO BRIEFCASE, which I can only assume is also an anagram. Also in the article itself are some odd names ("cumentexis" and "Brationst") ...
by Rich Talbot-Watkins
Fri Dec 15, 2017 10:58 am
Forum: stardot.org.uk
Topic: private messages
Replies: 12
Views: 386

Re: private messages

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by Rich Talbot-Watkins
Fri Dec 15, 2017 8:35 am
Forum: software: other
Topic: Wishful thinking - B+ OS, C/C++ DFS/ADFS
Replies: 16
Views: 602

Re: Wishful thinking - B+ OS, C/C++ DFS/ADFS

If memory serves, Exile uses the illegal opcodes while decrypting itself, and E-Type uses them for scaling graphics. This is a dim, distant memory from when I had implemented some of them incorrectly, way back in the '90s. Oooh, that's surprising, but also kinda cool. Obviously the Beeb versions ca...
by Rich Talbot-Watkins
Fri Dec 15, 2017 8:25 am
Forum: software: classic games
Topic: Unused Citadel bits
Replies: 42
Views: 1731

Re: Unused Citadel bits

I'm guessing the lack of the chimney shaft in that picture is some other off-by-one bug (maybe the last rectangle or something?). Does Citadel's sprite routine have the ability to recolour sprites as well as flip them (going by the shield whose right half has different colours to the left half)?
by Rich Talbot-Watkins
Thu Dec 14, 2017 9:19 pm
Forum: software: other
Topic: Wishful thinking - B+ OS, C/C++ DFS/ADFS
Replies: 16
Views: 602

Re: Wishful thinking - B+ OS, C/C++ DFS/ADFS

ThomasHarte wrote:Though with a processor swap it'll probably no longer run Exile or E-Type...

Why's that? Do the Electron versions exploit the illegal NMOS opcodes or something? :?:
by Rich Talbot-Watkins
Mon Dec 11, 2017 5:22 pm
Forum: software: classic games
Topic: Unused Citadel bits
Replies: 42
Views: 1731

Re: Unused Citadel bits

Interesting details with the strings! So what's the format for each screen then? I guess it must need a few chunks of data: - base texture - filled/solid tilemap (1 bit each I guess) - overlayed objects - triangles There's a thread here in which we talked about Citadel a little bit, and I mentioned ...
by Rich Talbot-Watkins
Mon Dec 11, 2017 3:22 pm
Forum: software: new games
Topic: New Release: Retro Software's WHITE LIGHT by Sarah Walker
Replies: 55
Views: 2503

Re: New Release: Retro Software's WHITE LIGHT by Sarah Walker

One reason for this is that Disc Doctor stores the variable 0D at &130 so any code that is loaded from &100 to &1A0 will end up with a 0D over what was stored at &130. Really?!! That's terrible! No wonder certain games used to have problems. It was pretty common to use the bottom of...
by Rich Talbot-Watkins
Mon Dec 11, 2017 3:17 pm
Forum: software: other
Topic: Mini Office II disk protection (Split from: Legacy of the BBC Micro User magazine / Database Publications Ltd)
Replies: 23
Views: 771

Re: Mini Office II disk protection (Split from: Legacy of the BBC Micro User magazine / Database Publications Ltd)

A "Data CRC error" will occur if reading with a different size, since the CRC is the two bytes immediately following the data. I suppose you could create a 2048 byte sector which will give an accurate CRC with every read, by having the correct CRC after 128, 256, 512 and 1024 bytes. Did y...
by Rich Talbot-Watkins
Mon Dec 11, 2017 11:04 am
Forum: software: new games
Topic: New Release: Retro Software's WHITE LIGHT by Sarah Walker
Replies: 55
Views: 2503

Re: New Release: Retro Software's WHITE LIGHT by Sarah Walker

Just had a quick go in B-Em - fantastic work as ever! Going to give it a proper blast this evening! One thing worth mentioning - it breaks in an absolutely crazy way if you have the Disc Doctor ROM installed (as I do in all my emulator configs). Can't really imagine why, but Disc Doctor was fairly w...
by Rich Talbot-Watkins
Mon Dec 11, 2017 10:26 am
Forum: software: other
Topic: Mini Office II disk protection (Split from: Legacy of the BBC Micro User magazine / Database Publications Ltd)
Replies: 23
Views: 771

Re: Mini Office II disk protection (Split from: Legacy of the BBC Micro User magazine / Database Publications Ltd)

Good to see you back AJH! I guess the other thing you need to do when trying to make a sector dump is to try reading each sector with every possible sector size, not just the one reported in the IDs. (I presume you get an error when trying to read a sector with a different size to its actual size?)....

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