Spectrum Computing

Thank you, I understand. Yes, I didn't know what << meant. Several years ago, I made a 3D vector game in Z80 assembly with coloured non-transparent city buildings, so I needed to sort them according to their distances from the player "camera". It works well on the Spectrum, but I always lo...

Found this which has more terms of the approximation. https://www.flipcode.com/archives/Fast_Approximate_Distance_Functions.shtml u32 approx_distance( s32 dx, s32 dy ) { u32 min, max; if ( dx < 0 ) dx = -dx; if ( dy < 0 ) dy = -dy; if ( dx < dy ) { min = dx; max = dy; } else { min = dy; max = dx; }...

Snakes & Hazards, Xmas Ludo, Shove-a-Sledge, Tiddly Drinks. On Spectrum 48K, it plays music through the beeper.

Gilligan's Gold

Was this game finished? I tried the version from this archive and it shows some flickering during the gameplay.

I have found some articles from 1982-1985 about Spectrum musical hardware and software. I am not sure if all this is in the database, probably only XRI Micon and its Step Time Sequencer. http://www.muzines.co.uk/articles/micromidi/6021 http://www.muzines.co.uk/articles/micro-music/4409 http://www.mu...

When I saw my friend's Amiga 500 in 1989, I really liked it. The graphic operating system looked cute and some games with 32 colours and stereo music were very atmospheric. Only the case design and the flickering white booting screen with 50 Hz didn't look great, but comparing to my Spectrum +2 it w...

I always liked Booty, but I must agree with your frustration points. I would appreciate if someone could find POKEs for: Much bigger time limit to find the last key. To move the point of collection of an item to its centre. Better detection for moving platforms. Now it's too easy to fall down throug...

BASIC Interactive Assembler System - the file BASICInteractiveAssemblerSystem(EN).txt.zip can't be downloaded. By the way, this system looks very good for learning assembler. The user can write an assembler source code directly in the normal Spectrum Basic program, so he can combine both types and t...

I've noticed an interesting looking new Spectrum game:
https://www.youtube.com/watch?v=7LMrndvxwPI
Below the video, there is also a link to download the game.

Put breakpoint in emulator on write to desired memory area. Then you can find what code does corruption. Yes, exactly. That's how I found the bug. But I was doing it in Fuse, so it was more difficult. I don't know if the Fuse debugger doesn't have an option for a memory range breakpoint, but I didn...

I was also thinking about showing it, but finally I found a bug. It's my first assembler project using sprites, so I made a lot of mistakes and rewrote almost everything several times. This time I was using LDI for drawing on the right screen edge and I forgot that when the address crosses the scree...

If you haven't seen it, my Speccy Z80 handbook has a brief section on interrupts: http://railtron.com/files/spectrum/ZX-Z80.pdf It also tells you how to scan the keyboard, since the ROM interrupt will no longer be doing that for you. A nice handbook, thanks! First up, disable interrupts with DI . N...

R-Tape wrote: ↑Wed Oct 19, 2022 1:17 pm I know it's a 48K program, but are you testing it in 48K emulation? If you're emulating +2A or +3, even in 48K mode that bit of RAM is used when tape loading (or something).

Yes, I am testing it in 48K emulation, but it's good to know it about +2A and +3, thanks.

While you may not use any ROM routines in your code, the interrupt will still be running and that might affect the Sys Vars that are placed not much below 24000. To be absolutely sure that you can use the Sys Var area for your own purposes, you should either have interrupts disabled ALL the time OR...

No idea about the corruption, but there's something weird going on. If you've done DI then that HALT should just freeze forever. It'll never come out of it if interrupts aren't on. If interrupts are on though you'll have to be careful as the ROM routines assume IY is always the same and uses it to ...

I am trying to make a program in assembler with a lot of graphics, so I would like to use all available Spectrum 48K memory. When my program block starts at the address 25000, everyting is OK. When I move it to 24000, it starts normally, but after some time it gets corrupted in the area between 2400...

catmeows wrote: ↑Wed Mar 02, 2022 5:11 pm Or AND(HL) and use $FF for jump and $00 for skip.

Do you mean "and (hl)" instead of "ld a,(hl): and a" ? But what if a=0 ? Then I think the result would be 0 in any case.

Ast A. Moore wrote: ↑Wed Mar 02, 2022 7:37 pm Why not use CPI/CPIR?

I was also thining about it, but when I made a test, it looked more complicated than before. But maybe I just didn't understand how it should be done.

Thank you, I understand. I don't know why, but it took me some time to understand the idea.

I was also thinking about a table, but wouldn't it be slower than my example? The table will only do one check - it will go straight to the answer it needs. It might not be quicker than the first check in your example, but by the time you're doing a third or fourth comparison against the same initi...

Though it would be better to have codes in continuing range and resolve jump by one or two conditional branches. For example it is useless to test '45' when you can test 'less than 44' and 'more than 46'. You can also look on binary search : one can resolve any value between 0 and 255 by 8 tests on...

Pobulous wrote: ↑Wed Mar 02, 2022 4:25 pm You could use a lookup table aligned on 256 byte boundary
Values of 1 for jump or zero to not jump

LD H, (base of table)
LD L, number to compare
LD A,(HL)
AND A
JP NZ, address

I was also thinking about a table, but wouldn't it be slower than my example?

Is it possible to speed up this type of code? If a number in a register is equal to any of these numbers, the program jumps to an address. The address is the same for all tests.

Raoh_hokuto_shinken wrote: ↑Thu Feb 24, 2022 5:51 pm Corn-Hunter (with Jean-Michel Jarre intro music "Popcorn"):

It's quite interesting to hear pseudo-multichannel music from an old Basic magazine type-in. By the way, Popcorn wasn't made by Jarre.