Spectrum Computing

I loved Dizzy and his many sequels, so they'd easily take the top spot, except I'm applying my own arbitrary rules again that I actually have to remember the demo and not the full game so they're out of the running. So with those completely nonsense rules in place: 1) Steg the slug - an underrated g...

also note that by destroying sysvars you won't be able to use +3DOS. you need to call ROM interrupt handler to eventually turn drive motor off, and it uses some other sysvars too. tbh, i never bothered to get rid of sysvars, and i don't think you need to. ;-) hey, you wasted 257 bytes on interrupt ...

Terrible photography, but familiar nonetheless

Would popping the registers off the stack between levels help? If you're writing "clean" code, the number of things you PUSH and POP should always align (not that CALL is also a PUSH and RET is also a POP) in such circumstances. So you should be reasonably confident that your stack is in ...

I mean, you could probably find out exactly by just supplying a zx81 ROM image into a spectrum emulator. It won't be very useful regardless, because the zx81 ROM will have absolutely no idea how to drive the screen or poll the keyboard, it'll just fill RAM up with garbage and sit around waiting.

It's been also said about Master Chief earlier, but tbh I'm not sure where does this notion come from. Both these characters have very strong identity, (visual, at least) and the fact that they don't say much or that MC is wearing a helmet doesn't stop me (and clearly a lot of other people) from re...

goodboy wrote: ↑Mon Apr 08, 2024 5:30 pm the shadow of the beast also belongs to this category, she's not playable

Some would say the same of the final game....

It's very hard, so I've tried to stick to games I remember playing the demos of back in the day and enjoying. Which, to some extent, excludes those I bought the game of because I'll have forgotten the demo but hey ho. 1) Dominator - I remember loading this one, lots. As a massive R-Type fan I loved ...

I may have shot down my own arguments here. Just asked my girlfriend - who is not a gamer unless you count The Sims or those rollercoaster games - to name a videogame character. Without the slightest pause: "Lara Croft". Can't say I'm surprised, I think some people here have a very skewed...

you prolly have the stack somewhere around $FF00, or something. so when you switched the banks, the window [$C000..$FFFF] moved to another memory region… and your stack stays in the old one. ;-) just remember that memory area [$C000..$FFFF] is affected by switch, and design your code around that. I...

this will limit the ways to use the system. the idea is that you can move the sprites anywhere in your code, when you want it, not when the system wants you to do it. you command — the system obeys, not vice versa. ;-) Doing this in interrupts will make the code exponentially harder to use. Because...

I bet you still have interrupts enabled? If you do, you need to update the relevant system variables before you switch banks. If you don't do that, there is every chance the system will sweep in when you're not looking, do some stuff and then "restore" the correct banking as per the variab...

Honestly I don't think it's the prefixes I'd be bothered about. If I wanted to tweak the Z80 design, removing the need to re-read instructions like LDIR would've been where I'd go next. And maybe redesign instructions like OTIR to be better suited to a 16-bit IO range (use DE as the destination rath...

DEC SP/INC SP are silly instructions too. It would be loads better if it decremented/incremented by 2, changing by 1 has no use I can think of, since you always push a word to the stack. If it incremented by 2 it would just be like discarding the value on the top of the stack (I usually use POP AF ...

Well, the decision was mostly made for them. A design goal of the Z80 was to be able to run all 8080 code at a binary level, so you couldn't really just swap out less used instructions even if you wanted to. Whether that was really necessary is a different question I suspect the actual instruction s...

Yeah, I've heard that said and I didn't actually mean to drive down there, it's just that an incident with my car meant I had to stop in Norwich city centre for a while and when I resumed going to my actual destination, I saw myself heading down that very road. Even though it was a Thursday afterno...

Almost certainly Amigas. From what I hear of Barcadia, you have to pay £10 for a bunch of American quarters, which gets you about 10 goes on the arcade machines, it's also located on probably the worst street for dealing with drunk clubbing types. Meanwhile, five minutes away there is an arcade in t...

Ah, so a hand coded reimplementation of the Speccy ROM in 6502. I'd have guessed it had to be something like that to function at any kind of speed, actually emulating a Z80 would've been a very tall order. Impressive that he also got it loading actual ZX tapes via the C64's slightly weird tape syste...

There are also Dizzy (Amstrad CPC) If you look at the internals of Dizzy, it's pretty obvious the primary target platform was the Spectrum. The CPC version stores all the colour numbers in Spectrum format and then remaps them onto its 4 colour mode (this is why there are no blue background objects,...

Honestly, I'd have thought the requirements for running in just 16K (tiny amount of RAM, can't use IM2 etc) would make such a thing extremely unlikely and little more than a proof of concept if it did exist. I can't even remember games that would be expanded on a 48K machine, I think the prevalence ...

Ultimately ChatGPT (and all LLMs) is essentially predictive text on steroids. It's very, very good at generating plausible looking text but it never actually understands what it is doing. It's why it might get a long way to producing vaguely correct code, especially in boilerplate scenarios, but it'...

I've only had a quick squint at the code, but can't quite see how your interrupts are supposed to work. halt seems to set an internal variable but I can't see where it is used. The actual implementation of maskable interrupts seems to be inside an nmi function (which seems weird) but I can't see whe...

It looks like a stack crash, some code got caught in an infinite loop and is PUSHing the same six bytes onto the stack over and over. It's not quite the same six bytes, there looks to be 8 bytes before it repeats in the screen data, but they're different on different lines which is curious. Also th...

So the recommended speed is 12.5fps? Probably I didn't get the message right. I was precisely asking for responsiveness at 25fps but everything else moving at a more moderate pace which would make sense. At 25fps, when a movement key is pressed the sprite starts moving in the screen around 1/25s la...

Oblique projection is a type of parallel projection: ... lines of sight or projection lines, are parallel to each other. I could see crossing lines (with some imagination). But i don't see lines at left side of screen are parallel to lines at right side. Wall lines are parallel, but they are at the...