Spectrum Computing

Well, if you want really quick and dirty sqr you can also use identity log (sqrt(x)) = log(x)/2 which can be implemented as two reads of LUT and one shift. Probably best thing on this approach is that you can reuse log and antilog tables also for fast approximation of division which is also quite ex...

I think Jetpack (and other Ultimate games) erase and draw sprite at the same time, line by line. It sounds like horrible idea but sprites usually move just a little bit so this method basically replaces flickering by possible tearing. Well, you can check how it looks on YT yourself.

i had to look at (and edit) the sample game. standard line editor sux, so i wrote the fullscreen one. and implemented 64 columns print driver for it. ;-) https://files.catbox.moe/xxnhla.png the editor works in any mode, though (32, 42, 64). it has line yank/insert, and nice incremental search. sadl...

Having LD A,A and so on is an 8080 design choice, and the Z80 designers had to keep it that way for compatibility's sake, since they were official instructions. When Motorola planned successor for 6800, they asked cutomers if they need binary compatibility or if source code compatibilty would be go...

Well, I really wish Z80 had more addressing modes. Once you try 6809, you see how much time you waste with pointer arithmetic on Z80. Otherwise, LDI, LDD would be nice without prefix. And yes, CALL cc are used less than one would expect. My ideal 8 bit CPU would be mix of 6809 and ZB0, possibly with...

Nevíte někdo náhodou kde je v této hře zakódována mapa?rutina na adrese 30252 vykresluje na obrazovku a a načítá data určené IX 63310.odkud se zapisuje na tuto adresu? Diky Translation: Hi, has anyone idea how is map stored in Cyclone game. There is draw routine at 30252 and uses data given by IX =...

Vera Cruz has French and Belgian authors. I'm not sure which of them was the coder but considering the long english tradition to wrongly recognize Mr. Poirot as French, I would count it.

For me, it is similar to movies. Some movies have 2 hours and you feel it is the right lenght, some other have 1 hour 20 minutes and you feel it is the right length. And then you have movies that ask for 2 hours and you feel they should be cut to 90 minutes. And also opposite, there are some movies ...

Or even better: Day 1: You join a super ambitious projects of an arcade conversion after a previous coder left. He stated he has problem with drinking and is not able to continue on the project. But at least he sends you source code of his work as TRD image for some obscure russian assembler you nev...

Interesting I’ve been writing what each line does but actually the block is much better. Do you have any rules around the size of a block? Single block does single thing clearScreen ; CLEAR SCREEN ; A = attribute ld hl, 16384 ld de, 16385 ld bc, 6144 ld (hl), 0 ldir ;clear pixels ld bc, 767 ld (hl)...

ParadigmShifter wrote: ↑Sat Jan 27, 2024 3:29 pm Well moral of that story is never ship your own implementation of a standard algorithm without first

And write unit tests. I have seen so many bugs that would be discovered even by the simplest test.

They even made a video camera that used audio cassettes, so cassette bandwidth is actually pretty impressive if pushed to the limits. https://www.popularmechanics.com/technology/gadgets/a25304/camcorder-audio-cassettes/ Yeah, i know about PXL camera. It Is such obscure toy hardware I cannot decide ...

TheMartian wrote: ↑Wed Jan 24, 2024 9:41 pm You actually need to press "M" while next to the key to grab it. In fact, it's quite realistic. Whenever I try to grab my keys running towards them I get hurt...

You martians are missing superpowers of earthlings, obviously.

I think that Seraphima and Wycheweald are awesome games and they deserve to be amongst the best of the year. I'm myself a small part of the team of Speccy Soccer and that third place makes me quite happy. That and also knowing that so many people played it and liked it. Thanks to all those who rele...

I have three: 1) To finish coding of shmup planned for WOOT 2023 (that is less or more sure thing) 2) Move on with Telebugs project (there is some uncertainity what we want to do) 3) Make a beat-em up game (I have very clear idea about WHAT and HOW, though I doubt my capability to draw sprites for t...

Looks interesting, can you explain that one in a bit more detail? I can't quite get my head around it... As HL is decreasing, it will rewrite second byte of JR instruction. Since series of multiple xors over chunk are deterministic, you can choose start value in A register such that result of XOR w...

hitm4n wrote: ↑Sun Jan 21, 2024 12:43 pm

Who is that guy in right bottom corner ?

Any ISR that would destroy HL would be most likely useless. What I mean than you can reserve space on stack like this: ld hl, -1000 ; reserve 1000 bytes add hl, sp ld sp, hl and free reserved memory like this ld hl, 1000 add hl, sp ld sp, hl basically any high level compiler supporting stack frame w...

ParadigmShifter wrote: ↑Sun Jan 21, 2024 6:28 pm If you change SP you need to do that inside a DI/EI block too.

Why you should not change stack pointer, Basic does that all thé time.

IMHO, you can use all space between STKEND and Z80 stack. Still, remember that USR is just Basic function and it should work even when it is part of more complex expression so you should not touch anything bellow STKEND.
But why not to reserve space directly on Z80 stack ?

Edit: 1) that 3E byte is mark for bottom of GOSUB stack 2) yes, FREE MEMORY is that one you want - use PRINT 65536-USR 7962 3) I would really use variable area: 3a) read value of VARS to get start of variable area 3b) reserve space for a dummy variable by calling MAKE-ROOM with HL=pointing to addres...

P.S. The goal is to allocate a large chunk of memory in your machine code without asking user to explicitly set RAMTOP. But RAMTOP is there exactly to limit memory used by Basic. Anything below it is not guaranteed. UDG area can only be moved explicitly, right? Unless something modifies UDG sys var...

The practical examples I see quite often: 1) store SP value directly as argument of LD SP, nnnn 2) update a byte/word value and inject new value back to computation code - RNGs use it quite often 3) compute jump argument for JR - very often it works as replacement for SWITCH CASE statement 4) variou...

In my opinion the tape is incomplete. I was looking what is on the tape (some sound routines, at least one screen fx routine, udgs and the compiler) and I think, it contains just last code block from game. When I was looking on some other games by same author I noticed the games usualy contain three...

https://www.youtube.com/watch?v=Iu_clMGOdTI https://www.youtube.com/watch?v=LlIn7Y2jt2I https://www.youtube.com/watch?v=Twc22gZkrRM https://www.youtube.com/watch?v=tLycESojiCU https://www.youtube.com/watch?v=PSErh0ZGpBw https://www.youtube.com/watch?v=n0g1tv1gXvk https://www.youtube.com/watch?v=vX2G...