Search found 1381 matches

by AndyC
Thu Mar 14, 2024 11:12 am
Forum: Sinclair Miscellaneous
Topic: That thing with the blue and magenta ladders (OUT)
Replies: 39
Views: 881

Re: That thing with the blue and magenta ladders (OUT)

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...
by AndyC
Tue Mar 12, 2024 9:11 am
Forum: Showcase your work!
Topic: Saboteur 2 mod
Replies: 53
Views: 2441

Re: Saboteur 2 mod

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...
by AndyC
Sun Mar 10, 2024 11:57 am
Forum: Games/Software
Topic: Oblique 3D Graphics - true or not?
Replies: 21
Views: 430

Re: Oblique 3D Graphics - true or not?

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...
by AndyC
Sun Mar 10, 2024 10:55 am
Forum: Games/Software
Topic: Oblique 3D Graphics - true or not?
Replies: 21
Views: 430

Re: Oblique 3D Graphics - true or not?

PANDEMIA . Fake perspective - that what exactly describes by feel of that screen. I think it is one-point perspective (see wiki) because all furniture lines should end in one point far away. "All objects will recede to points in the distance". https://en.wikipedia.org/wiki/Perspective_(gr...
by AndyC
Sat Mar 09, 2024 2:44 pm
Forum: Games/Software
Topic: Oblique 3D Graphics - true or not?
Replies: 21
Views: 430

Re: Oblique 3D Graphics - true or not?

Lethargeek wrote: Sat Mar 09, 2024 2:40 pm and the entire scene is not
Well it sort of is. There is no perspective (you can see the tiles on the walls are all parallel lines). It's just a really weird mash up of two oblique angles.
by AndyC
Sat Mar 09, 2024 12:42 pm
Forum: Games/Software
Topic: Oblique 3D Graphics - true or not?
Replies: 21
Views: 430

Re: Oblique 3D Graphics - true or not?

They're all oblique projections, since none of them apply perspective. There's always a possibility with this that the end result can "look odd" because your brain can interpret the image in multiple ways and none of them are entirely correct.
by AndyC
Sat Mar 09, 2024 10:48 am
Forum: Programming
Topic: Measuring frames/VSYNC
Replies: 10
Views: 515

Re: Measuring frames/VSYNC

One thing to bear in mind is that, unlike the Amiga, you're don't really have to worry about someone having a faster CPU. So a lot of the time HALT on it's own will suffice. If you're execution time per frame is very variable, I'd personally probably use my own interrupt routine rather than the ROM ...
by AndyC
Tue Mar 05, 2024 10:52 pm
Forum: Games/Software
Topic: How hard would it be to hack these racers?
Replies: 61
Views: 1710

Re: How hard would it be to hack these racers?

@AndyC But sprites in Enduro are much bigger and active screen area is also much bigger. I think the Enduro engine is just more advanced. Outrun effectively has to calculate and render two roads all the time (it's how branching and highways work), which requires significantly more maths than the si...
by AndyC
Tue Mar 05, 2024 7:19 pm
Forum: Games/Software
Topic: How hard would it be to hack these racers?
Replies: 61
Views: 1710

Re: How hard would it be to hack these racers?

toot_toot wrote: Tue Mar 05, 2024 7:08 pm It does make you think there’s a fundamental bug somewhere in Outrun that’s slowing things down.
Outrun has more features like multiple roads/branching etc. All of which makes things slower.
by AndyC
Tue Mar 05, 2024 6:52 pm
Forum: Games/Software
Topic: How hard would it be to hack these racers?
Replies: 61
Views: 1710

Re: How hard would it be to hack these racers?

The timer is probably just counting every X game frames, it's less accurate but fairer on a player since they don't get penalised for game slowdown that way. I can't off hand think of a reason the game would run slower on a 128, especially not the 48K version. Unless it's still using the ROM interru...
by AndyC
Tue Mar 05, 2024 1:36 pm
Forum: Sinclair Miscellaneous
Topic: That thing with the blue and magenta ladders (OUT)
Replies: 39
Views: 881

Re: That thing with the blue and magenta ladders (OUT)

ZXDunny wrote: Tue Mar 05, 2024 1:24 pm Yeah but the BASIC can and well... it did, y'know? With a single OUT.
Which is why I followed it with a paragraph about what probably happened....
by AndyC
Tue Mar 05, 2024 1:11 pm
Forum: Games/Software
Topic: How hard would it be to hack these racers?
Replies: 61
Views: 1710

Re: How hard would it be to hack these racers?

XoRRoX wrote: Tue Mar 05, 2024 12:51 pm As using the AY chip isn't as CPU-hungry as the beeper, I'm wondering if the 128k version plays faster.
Yeah, I would expect so unless it still has beeper FX (I can't remember off hand).
by AndyC
Tue Mar 05, 2024 1:10 pm
Forum: Sinclair Miscellaneous
Topic: That thing with the blue and magenta ladders (OUT)
Replies: 39
Views: 881

Re: That thing with the blue and magenta ladders (OUT)

When playing around with these things, RAM is usually mostly zero. And zero is NOP, so a jump almost anywhere has a high chance of hitting empty space and just running into the data structures up near RAMTOP. I'd hazard a guess that interpreting that as code leads to the sequence of instructions tha...
by AndyC
Tue Mar 05, 2024 11:27 am
Forum: Sinclair Miscellaneous
Topic: That thing with the blue and magenta ladders (OUT)
Replies: 39
Views: 881

Re: That thing with the blue and magenta ladders (OUT)

equinox wrote: Tue Mar 05, 2024 11:19 am What was the chance that you would fail to get through Skylab Landing Bay?
105%, approximately.
by AndyC
Tue Mar 05, 2024 8:37 am
Forum: Sinclair Miscellaneous
Topic: That thing with the blue and magenta ladders (OUT)
Replies: 39
Views: 881

Re: That thing with the blue and magenta ladders (OUT)

The point is that it can *run*/execute something, and not merely do a beep or border. Maybe it is a consequence but you did say this was totally impossible. 'sall. I said the hardware can't trigger something like that from a single OUT, but changing a paging register probably causes the machine to ...
by AndyC
Tue Mar 05, 2024 7:55 am
Forum: Programming
Topic: That thing with the bottom two lines
Replies: 19
Views: 760

Re: That thing with the bottom two lines

Let's try to ignore Icon Graphix ... Wait. Was that the one they gave away on an SU covertape at some point? The one where you had to play a music tape in the tape deck while you were using it or the keyboard routines didn't work correctly? Aside from that glaring bug, I seem to recall it wasn't ac...
by AndyC
Tue Mar 05, 2024 7:47 am
Forum: Sinclair Miscellaneous
Topic: That thing with the blue and magenta ladders (OUT)
Replies: 39
Views: 881

Re: That thing with the blue and magenta ladders (OUT)

ANDY APOLOGISE I stand by what I said. The OUT doesn't really do all the things you're seeing, it's just a consequence of what follows. The OUT swaps the paging arrangement to some unexpected configuration. At that point one of maybe four things could suddenly be true: 1) One of the other 128K ROMs...
by AndyC
Mon Mar 04, 2024 1:55 pm
Forum: Games/Software
Topic: £12 gets you "Free software for LIFE!", apparently.
Replies: 11
Views: 287

Re: £12 gets you "Free software for LIFE!", apparently.

Given that it has 50% more of both 'Great Utilities' and 'Adventure Games' than 'Arcade Games', I'm guessing it's an early PD library trying to vaguely disguise the fact that you're buying into a giant Cassette 50 scheme without the calculator watch or quality control, rather than a lending library...
by AndyC
Sun Mar 03, 2024 9:25 am
Forum: Games/Software
Topic: Devfinitive Edition (Keith Burkhill): vote
Replies: 29
Views: 596

Re: Devfinitive Edition (Keith Burkhill): vote

1. Gilligan's Gold
2. Commando
3. Ghosts and Goblins
by AndyC
Sat Mar 02, 2024 9:25 pm
Forum: Games/Software
Topic: Game versions 48K vs 128K
Replies: 30
Views: 674

Re: Game versions 48K vs 128K

I would have thought that any game that uses a backbuffer that is fully redrawn each gameloop on 128K would use that since it avoids having to copy the backbuffer to the screen? You'd think that, but it often wasn't the case. Probably a lot of developers had routines built for the 48K, which often ...
by AndyC
Sat Mar 02, 2024 7:30 pm
Forum: Games/Software
Topic: Game versions 48K vs 128K
Replies: 30
Views: 674

Re: Game versions 48K vs 128K

An emulator that can set a breakpoint on bit D3 of I/O address 7FFDh could be used to confirm it. Whether it's "interesting" enough for anyone to spend time investigating is another question I guess.
by AndyC
Sat Mar 02, 2024 5:58 pm
Forum: Games/Software
Topic: Game versions 48K vs 128K
Replies: 30
Views: 674

Re: Game versions 48K vs 128K

There's really two different situations, which can heavily influence the answer: A game that runs on both 48 and 128 machines. This probably accounts for the vast majority. Because you wouldn't want the game to break on 48k, you're limited in how you much you can really add. Commonly using the extra...
by AndyC
Fri Mar 01, 2024 10:41 pm
Forum: Games/Software
Topic: Could Knight Lore have been (a lot) faster?
Replies: 10
Views: 464

Re: Could Knight Lore have been (a lot) faster?

Not sure I agree. Consider Manic Miner: perhaps it could've run faster on some screens, or slower on others. Who knows? But would that have been desireable? For me, that's a resounding no. So far as I recall, Manic Miner's speed was its speed, screen through screen. I think in terms of 'experience ...
by AndyC
Fri Mar 01, 2024 10:04 pm
Forum: Games/Software
Topic: Could Knight Lore have been (a lot) faster?
Replies: 10
Views: 464

Re: Could Knight Lore have been (a lot) faster?

Yeah, there's no reason it couldn't run more like HoH. Dunno about frame rate locking, that's good in action games but when you're already running at pretty low frame rates it might not be entirely desirable.
by AndyC
Fri Mar 01, 2024 12:03 pm
Forum: Programming
Topic: That thing with the bottom two lines
Replies: 19
Views: 760

Re: That thing with the bottom two lines

On the Beeb you have that strange double-cursor mechanism where you have to LIST the desired line, cursor your way up there, and then hold down a special Copy key to re-enter it (or just the parts you want to keep). The Amstrad CPC (as far as I recall) involves entering EDIT 100 and then line 100 p...