Spectrum Computing

Ast A. Moore

I can get the X and Y bytes separately into A, or if I want both I can do LD BC,(sprite_XY) But I have to remember to define them in memory in the order Y,X, so that when I do a 2-byte fetch Y=>C and X=>B. Yes, it can be tricky to remember the low-endian byte order, but I often define such variable...

Ast A. Moore

Bubu wrote: ↑Sun May 09, 2021 12:28 pm Oooohhh, that frog can swim !!!!

Yup.

Ast A. Moore

Voted for Spectrum Cross, because that was the first game that taught me that you could incorporate machine code into BASIC.

I remember loading it, pressing BREAK, and spending some time figuring out how the sprites could be moved so smoothly in BASIC. Then it dawned on me . . .

Ast A. Moore

Under4Mhz wrote: ↑Sun May 09, 2021 3:25 am I'm pretty sure Klondike only allows you to put down Kings.

Yup. That’s how I remember it, too. That’s what makes the game fun, I think. If you could put down any card, the game would be too easy and mechanical.

Ast A. Moore

So far I've been using video recordings of lab experiments with appropriate values output to the screen, then using VLC to observe things frame by frame. Yeah, no, this is very limiting. With an RZX recording, you can set breakpoints close to when the bug occurs and examine the state of the machine...

Ast A. Moore

Looks great! Needs more control options. I’m not too keen on the QAOP scheme and rather use the Sinclair Joystick or, ideally, redefinable keys. Feel free to use my routine.

Ast A. Moore

Not strictly Z80, but it took me a very long time to realise the benefits of fixed point arithmetic in writing a 2D game. I was always thinking in terms of pixels and could never really get the kind of smoothness I wanted. Having read how Super Mario does it, the answer is obvious. Use 16-bit math ...

Ast A. Moore

Why? It’s no different than, say, IN A,(*) (where the full port address is formed by the contents of A placed in the top eight bits). I'm not sure - it feels like you're trying to scoop water out of a bucket, using the same bucket that's holding the water... :lol: I see what you mean, but in fact t...

Ast A. Moore

Morkin wrote: ↑Wed May 05, 2021 11:30 pm I still can't get my head around:
Code: Select all
LD H,(HL)
Just hurts my brain for some reason.

Why? It’s no different than, say, IN A,(*) (where the full port address is formed by the contents of A placed in the top eight bits).

Ast A. Moore

It’s good practice to walk away from a particular piece of code and work on something else, if only to give your brain a rest. Finding unusual bugs like those you’re describing can be daunting. I often run my game in an emulator while recording it to an RZX file. That way, if you catch a rare bug, y...

Ast A. Moore

I remember ChibiAkumas. He was a little touchy, wasn’t he? I watched a couple of his videos and I think they were quite good.

Ast A. Moore

R-Tape wrote: ↑Wed May 05, 2021 9:58 am My first Sedge Warbler of the year on the walk to work this morning. Keep your ears peeled!

Gotta play with the volume and tone controls.

Ast A. Moore

Renegade
Target: Renegade
Flying Shark
Nether Earth

Ast A. Moore

Bubu wrote: ↑Tue May 04, 2021 10:02 pm In which screen could I get to that bug?

Any screen where you walk on a platform that is high enough so that when you are hit by an enemy mid-jump, it causes you to brush the top of the screen.

Ast A. Moore

For those of you enjoying Exolon, I have a bug-fixed version.

Ast A. Moore

Bubu wrote: ↑Tue May 04, 2021 7:51 pm Or even:
Code: Select all
ex de, hl
ex de, ix

Nope. EX DE,IX is not a valid Z80 instruction.

Ast A. Moore

presh wrote: ↑Tue May 04, 2021 5:34 pm

Code: Select all

; LD BC, IX
LD B, IXH   ; ok
LD C, IXL   ; ok

; LD HL, IX
LD H, IXH   ; nope!
LD L, IHL   ; nope!

; instead, have to do:
LD D, IXH
LD E, IHL
EX DE, HL

; or, if DE is unavailable:
LD A, IXH
LD H, A
LD A, IXL
LD L, A

Or simply:

Code: Select all

push ix		;2 bytes
pop hl 		;(or any other register) 1 byte

Ast A. Moore

DR400 wrote: ↑Sun May 02, 2021 10:32 pm Are there any other 'new' replacement ULA's out there similar to the NEBULA?

Sometimes it’s actually cheaper to get a few “untested” Spectrum boards and harvest a ULA from them, than to buy a modern ULA replacement.

Ast A. Moore

Was going to swap the ULA as a test with the one in my working Issue 2 , but not sure that's the problem, are the ULA's swappable between issue 2's &3's ? Generally, ULAs are backward compatible. That is, you can use a later version of the ULA in any board that came out before it, but not the o...

Ast A. Moore

Just make sure you use the headphone output—something that can drive a decent pair or high-impedance cans—not the line-level output.

Ast A. Moore

For the life of me I can’t remember what the first Spectrum game I played was. I distinctly remember a “compilation” tape made a friend that had Knight Lore among other things on it. Then, for some reason, Turbo Esprit springs to mind, but neither was the first game I played.

Ast A. Moore

I was very young when I discovered that Spectrum colours were perfect for creating a fade effect (from 0 to 7 or from 7 to 0) in my BASIC programs, especially when using a black and white TV or monitor. However, I still don't understand the logic behind it. Can anyone please explain it in layman's ...

Ast A. Moore

Einar Saukas wrote: ↑Thu Apr 29, 2021 1:04 am
Ast A. Moore wrote: ↑Wed Apr 28, 2021 10:18 pm Dark Fusion pulls off some pretty amazing stuff in the animated menu with multichannel beeper music.
That's a weird game...

It is weird.

Ast A. Moore

Stefan wrote: ↑Wed Apr 28, 2021 10:55 pm The menu only consists of a three level parallax star field and an attribute flash of the selected control method.

That still takes up quite a lot of the CPU cycles (considering how many are needed to play the multichannel sound). The player and the animation must be decently optimized.

Ast A. Moore

Dark Fusion pulls off some pretty amazing stuff in the animated menu with multichannel beeper music.

Spectrum Computing

Search found 2641 matches

Re: LD HL,(NN)

Re: Clone Wars (Frogger): vote

Re: Clone Wars (Frogger): vote

Re: Klondike Solitaire

Re: Overhead driving engine development

Re: Klondike Solitaire

Re: Z80 things that weren't obvious that you wish you'd known earlier

Re: Z80 things that weren't obvious that you wish you'd known earlier

Re: Z80 things that weren't obvious that you wish you'd known earlier

Re: Overhead driving engine development

Re: Learn Multiplatform Assembly Programming with ChibiAkumas!

Re: The Sedge Warbler - The official mascot of the Spectrum

Re: Games that you never stop playing... year after year

Re: Games that you never stop playing... year after year

Re: Games that you never stop playing... year after year

Re: Z80 things that weren't obvious that you wish you'd known earlier

Re: Z80 things that weren't obvious that you wish you'd known earlier

Re: Issue 3B - White screen, Retroleum smart card runs - Screen corrupt

Re: Issue 3B - White screen, Retroleum smart card runs - Screen corrupt

Re: ZX Spectrum Issue 3 not loading and I've tried the obvious

Re: Do you remember the first time?

Re: Question about Spectrum colours

Re: Beeper music during gameplay/action

Re: Beeper music during gameplay/action

Re: Beeper music during gameplay/action