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Edit: Ah, does &DC2 contain the ROM bank number of the current file system? That might make sense with some of the later code where it is attempting to write to every ROM bank except the for the bank number stored in &93. I think this is where the code is trying to establish which banks con...

It's resetting all the vectors back to their OS default handlers. &FFB6 contains the size of the default vector table, and &FFB7/&FFB8 contains a pointer to the table in the OS. Normally I've seen this in the context of a protection system trying to ensure that you haven't installed a ba...

Hmm. Looks like I am processing Esc twice - once to stop the program and also sending it on the command line. I wonder how I'll distinguish between those 2 cases.. What happens if you press and hold Escape? Do you get repeated Escape conditions processed by BASIC? This is just a roundabout way of p...

hoglet's BASIC4r32 source that Tom linked (here) can be assembled on Windows with BeebAsm, which you can find here!

I used to use it for designing game sprites back then. With a BASIC program to generate the raw sprite data by plotting sprites to the screen (PLOT &ED,0,1023-height*4) and reading the bytes out.

Yep! It uses the rest of itself when softloaded in Sideways RAM as sprite storage space, instead of claiming private workspace. Which means it's not ROMable. But the code is more or less the same as the GXR sprite code.

Ha, for a moment I thought you'd implemented this for reals!

Here's the 80 track version of the Master 128 Welcome Disk that I remember and love. The 80 track version has some extras on it, like the Acorn Sprite ROM (in the LIBRARY directory).

hoglet wrote: ↑Sun Dec 31, 2023 12:23 pm

Code: Select all

    1CLS:REPEATVDU9EORABS(VPOS^2-POS^2)MOD6=3ANDPOS<19AND35:UNTILVPOS>18

Just noticed that this one works in fundamentally the same way as mine, using a*a-b*b mod 6 as the condition for drawing a star vs a space. Bravo!

Did you enter those rtw? I didn't spot them in the video...I thought I'd got the third smallest BASIC program but evidently not. No, I didn't bother! Just thought I'd keep it here on Stardot where it matters :wink: Just shrunk mine down to 47 bytes using that great EOR/AND trick to avoid needing ex...

I did it in one line of BASIC:

Owlet link (50 bytes)

and later realised I could save another byte by splitting it over two lines and making it a bit more ugly:

Owlet link (49 bytes)

I could probably explain the incremental process that led to that solution in case anyone were interested!

Last year I managed to find an absurd way to plot the Christmas tree star using discrete cosine transform. Can't think of an equally absurd way to do this one so I'll probably stop now with the boring solution that I've got.

Yeah quite right. I'm so used to writing for 8bpp modes. So only the second approach works for Mode 9.

I'm quite rusty on Archimedes coding as you can tell!

Hey Robin, yeah shifts by register are slower, so you'd ideally want 4 different routines in Mode 13, or 4 shifted versions of the sprite.

Yep I think my register allocation is a bit off in those examples, but hopefully it's a good start!

On the Beeb, since it works byte-at-a-time, the "0 as mask" thing is easily done with a 256 byte lookup table which yields an appropriate mask byte for each value - but that approach wouldn't work on the ARM so you'd have to do it without a table which is probably much slower. One approach...

wmd wrote: ↑Mon Dec 04, 2023 4:40 pm Oh, I didn't realise Tom Cooper's stuff was PD / shareware. I think I have everything of his.

All of his PD games, I should've said! The later stuff (e.g. Hamsters, Darkwood) were all commercial.

Also, all of Tom Cooper's games seem to be missing from that list. Can't remember anything other than Son of Gyrinus right now, but fairly sure there were more!

I think Chuckie Egg and Daredevil Denis were Archimedes ports from the BBC versions by Michael Foot. They were essentially the original 6502 code "compiled" into C, with an extra layer of metadata on the graphics data to provide higher bit depth graphics. That'd be why the main character s...

Oh no - It's looking like I dreamt this feature up, or maybe it was for a different system? Any emulator coders out there --- this would be a useful feature, please! I feel like jsbeeb used to work like this (even showed the current raster position) but then something about the rendering code chang...

It does seem to be b-em. In main.c there is this table: const emu_speed_t emu_speeds[NUM_EMU_SPEEDS] = { { "10%", 1.0 / (50.0 * 0.10), 1 }, { "25%", 1.0 / (50.0 * 0.25), 1 }, { "50%", 1.0 / (50.0 * 0.50), 1 }, { "75%", 1.0 / (50.0 * 0.75), 1 }, { "100%&q...

Maybe try something like:
for a bit more precision!

Basically MUL can take up to 17 cycles to execute, depending on how big the second operand is. It keeps shifting out the bottom two bits each cycle until it's zero. So, in your case, when that operand is 160, I would expect it to take five cycles to execute: 1 to fetch the opcode, and 4 to perform t...

Ugh yeah. Thanks! (going to correct that snippet)

So used to setting P% inside a loop.

If you're just CALLing that 50,000 times, I imagine that's not a fair test as the majority of the time you measure will just be the overhead of the CALL. A fairer test would be to literally assemble that snippet 50,000 times and call it once, i.e. DIM code% 50000*8+4 P%=code% FOR c%=1 TO 50000 [OPT ...

Sounds a bit complicated to me! I just remember it as:

- consider the operand to be a signed 8 bit value (0...127, -128...-1)
- the branch destination is the address of the instruction which follows the branch, plus the signed offset.

I wonder if it was going to employ the same diagonal scrolling tech as used in Fortress? Someone out there must be in contact with Matt as he was featured not so long ago in the World In Pixels book.

Seems more that the problem is that C99 needs to be enabled. I assume this is a third-party library.

Instead of adding new keywords for this, I'd just try to make ASM work with assigning variables too. Seems like the simplest and most obvious solution to me. The original problem of assigning variables inside a macro which needs to be hoisted out of the macro instance's scope still wouldn't be solve...

The C and the G are also unusually closed. It's quite a clear pleasing font though - I'd use it as my coding font if there were a digital fixed-width version.

Ah yeah, that makes sense. Not that I ever thought to abbreviate *ADFS in my life!