Crazyace

Having scroll registers would have been great though. The STe was just a little too late - by the time it came out developers couldn't ignore the base ST model - so any support would have to be extra work. Personally I'd have been happy with a word addressable screen base - as that would solve the problems for vertical scrollers at least. ( I wonder what the chances were of a ~10MHz 68000 at the time - you could use the same crystal found on the NES , /2 for CPU, /6 for 3.58 NTSC colour , or slightly different crystal /5 for 4.43 PAL colour )

No problem, GPRIOR0 and 23 colours per scanline ( scrolled ) would be a big advantage to the A8 apart from it having quite stringent limitations - The best image I saw was the Tetris game in the other thread. That's why I treat it in the same way as the 48 colour/line Spectrum 512, which is also limited , but has quite an impact. ( It might be interesting to try to reproduce a particular image if you've got something in mind though ) I've seen some of the Photochrome pictures that look pretty amazing, but I guess they are in the same class as the hip mode pictures on the A8 - they are using 2 frames to get effectively 16 shades rather than 8 , but the flickering seems a lot less noticeable than some of the A8 pictures. I guess that's because the A8 is trying to mix a base colour with a brightness , but the ST is just trying to flicker between two consecutive brightnesses to suggest an inbetween value. Mr Robot is a game that I couldn't see any problem with replicating on the ST though, so that's why I raised it. ( The character animation might seem complex, but there's nowhere like a full screen animating on any of the levels )

Well, your attention to detail is the thing that will make it a great version of the game - I had a look at the PC Engine version, and if you made a version with no background at all it would still be amazing. ( I keep wondering what the XL would have been like if it had been designed with Beeb style components ... more bandwidth, 160 pixel GTIA modes )

Whatever, You dismiss the 640 by 4 colour and 320 by 16 colour pixel screen modes on the ST as any kind of advantage, and concentrate on the 80 pixel by 16 colour scroller. As I said - there seem to be demos that already do this on the ST, so I don't feel the need to make another one. Please back this up? Mr Robot doesn't use 16 shades - it's completely non GTIA. What are you comparing a static ST image with? Everything I've seen looks technically way better than the A8 best. ( And why are you bringing CGA into it again - the discussion is A8 vs ST )

Have you considered using bitmap rather than character mode? ( One of my favorite A8 games is bandits - which pretty much did everything in bitmap mode - although it had a rather cavalier attitude towards framerate at times ) ( Just thinking about Zalaga on the BBC as a good shooter - nowhere near as complex as galaga88 though )

Owned: ZX80 Spectrum Atari 800 C64 Amstrad CPC664 800XL QL 4160STe Amiga 2000 Various PC's 7800 Net Yaroze PS2 linux PS3 linux Saturn Dreamcast Xbox Gamecube Wii Xbox360 Retro ( now ): Plus4 2600 XE GS 130XE Jaguar 1040ST ( not tested, no room to set up on desk - and emulators pretty good ) Colecovision SuperCassetteVision

It's all a long time ago now - Once I moved on to coding on a host PC I switched to using Brief in 132 column mode ( I think on some Cirrus Logic video card? )

Actually I find that I haven't used my Saturn or Dreamcast for quite a long time now. Most of the games I'd really like to play ( enough to set up the machines ) are light gun games, and both my main TV - and the TV that my kids use in their room, are LCD's which dont work with light guns All of the old CRT monitors I used to use for gaming have gone, and with them the era of gun games ( Point Blank, Time Crisis, Virtua Cop, House of the Dead - all just gathering dust now )

I've never had any problems reading 80 column txt on any TV I had via RGB ( I had one of these ( Ferguson mc-01 http://www.worldofspectrum.org/showmag.cgi?mag=YourComputer/Issue8411/Pages/YourComputer841100192.jpg ) that I used with my 800(via s-vhs) and my ST for a while before I got a Trinitron RGB/Composite monitor. ( Like this one http://upload.wikimedia.org/wikipedia/en/thumb/3/3a/Trinitron_computer.JPG/800px-Trinitron_computer.JPG )

Good for you - I'm glad the rest of the gaming world took to graphics 9 so much Several demos seem to scroll overscanned full screen images with more than 16 colours, so I wouldn't say it's impossible though. Text modes are really useful - I'm not sure I'd include Mr Robot as something impossible to do on the ST though. But you can't reproduce 320x200x16 colours per pixel in any way possible on the A8 - ( and forget 640 pixels ). On the ST I can reproduce any display on the A8 - it may just take more time. Therefore I say that the ST display is superior. It's more colors and less shades. So it's a trade-off since now ST has problems representing some of the gradiences and shaded images of A8. So not a clear cut win for ST. Humans perceive luminances more than colors-- just study the TV signal construction. So don't just declare ST wins. I rather have more shades. As I stated before, I rather have 64 shades and 4 colors. The pallette on the A8 only has 8 shades, so it's a fair comparision 512 palletted colours vs 128 palletted colours. Feel free to put abuse of joystick port as an A8 advantage - I won't argue with your opinion on that That's the biggest bullcrap you have written thus far. I can also say parallel ports for laplink, ZIP drives, etc. is utter abuse of the parallel port; you need help. I suppose putting in bidirectionality in the joystick ports was a big mistake or some accident by Atari. SYNC is ABUSE of video circuit on ST, but doing I/O is perfectly good use of joysticks as PIA wasn't just meant for reading digital joysticks. I'm not arguing with you? - so why are you continuing. I'm quite happy with the advantages you've already given for the extra use of joystick ports.

It sound's pretty flexible ( mind you the A8 OS was always pretty cool in the way device drivers worked. ) - I never looked at the internals of gem/drdos though - but don't they have similar concepts? ( For games on both machines it was just boot sector then take over the hardware )

Having a full system bus connector ( or even r/w ) on the cart would have been great - I don't know why Atari didn't - maybe the idea was that all of the interfaces were already present on the machine. It was annoying having to 'spoof' the write for Replay. Did the PBI give you dma access though? ( like the Commodore REU's did )

The Amiga had all of the cool hardware - I think I felt a bit more warmly about the ST than you, as I'd just been programming for the QL ( which was pretty slow - but at least had a nibble screen mode. ( Also the Amiga 1000 was way way more expensive than an ST )

The 400 and 800 didn't have this capability though? ( and I guess you could implement a rom device on the ST via the cartridge port if you wanted ) so I expect what you're comparing is the XL PBI to something like the internal bus connector in the Mega ST machines? It's definitely more flexible than the DMA interface though.

I've got games that I loved on both platforms - from Drol and Bandits on the A8 which hardly use any special h/w , Preppie and Rally Speedway , through Lemmings and Dungeon Keeper , Kick off ( and Sensible soccer ), Captain Blood and Another World

What is S.Y.N.C ? I've heard of sync scrolling ( short for synchronisation I guess) - but not S.Y.N.C Please only concentrate on ST ( or A8 ) in this topic - you keep on bringing up CGA for some reason - maybe you're getting confused about something completely different on that card.

I wasn't going to reply, but I guess I did invite the response A8 graphics modes are also lores - but I was being pedantic about the quarter screen , so I'm not going to use that argument as an advantage for ST. Does mixing modes work with scrolling as well? ( In software it's a bit trivial for the ST - but I've never looked at whether you could switch 320-640 mode in the middle of the screen ) STe was when people already went for Amiga/PCs. GTIA was when 8-bit was still peaking and natural upgrade (backward compatible). If ST had been compatible with A8, nobody would be debating this issue. I was thinking MegaST for blitter , but you're correct, most A8 machines had GTIA, - and all of the scrolling was present on CTIA only. I'll stick with code samples that only require a standard 520ST. Rubbish - ST wins because it has higher resolution, higher colour modes. ( and what A8 modes are >16 colours - nothing in any of the hardware manuals I've got? ) ( I don't actually understand what your Mr Robot etc point is about though - can you clarify? ) Cut the "for launch" crap. ST not having RF modulator is worse than some 400/800 not having GTIA chips. 400/800 can pop in GTIA chip w/o soldering; you can't pop in a RF modulator in the ST. And I didn't put "lack of RF-modulator" in my list. Nor can you pop in a chip in the ST and give it more shades. 512 colours better than 128 has nothing to do with an RF modulator? - what is your point? Even with GTIA - I can happily say pallette of 512 colours is better than pallette of 128 colours, as the only 16 shade modes aren't palletted. Rubbish - RGB video is a better standard, ( and in Europe it was in a hell of a lot of TV's , with SCART/Peritel eventually standardising it ) Feel free to put abuse of joystick port as an A8 advantage - I won't argue with your opinion on that

No problem, I wrote it for my info more than anything else, and then posted it so at least there would be something to back up my claim. I'll see if I can get the Battlesquadron first level to assemble ( I couldn't fully recover one of my data discs ), as that uses vertical smooth scrolling ( 16 colours ) with roughly 20 scanlines worth of time. - Not speculation, but actual figures for a game. ... ST has video starting address at 256-byte alignment so unless you are doing some weird tricks, even vertical scrolling would be troublesome. Compare with EGA which has video starting address on BYTE alignment. Yup - it's using wierd tricks, but they work Sorry, but PRIOR 0 is GTIA doing its normal operations and not a big discovery-- just type something like: POKE 706,122:POKE 53263,255:POKE 53250,128 It has nothing to do with playing with video frequencies which has proven in history to cause problems/damage (i.e., CGA). It's very dodgy, as inside the chip you're driving two outputs at the same time into a single input. I guess it just luckily works because it's NMOS ( Curt can probably correct me if I'm wrong ) Please also read up on how the sync scrolling works - it doesn't actually change the frequency going to the monitor - it just confuses the shifter into displaying more valid infomation per line - just like wide playfield on A8, but via a hack. ( Not sure about what CGA has to do with it? only talking about A8 and ST here )

I meant screwing with (a6) by storing a5 on it since you have cycles @8*13. Sorry, those two lines aren't actually used anywhere - I was just sketching different routines before deciding which one to actually use ( I think I started with movem.l (a6)+,d0-d7/a0-a5 ; movem.l d0-d7/a0-a5,-(a7) - as I had a crazy thought about abusing the stack as a temporary register )

Emulation , and changing TV standards will eventually kill off old consoles. After all in a few years TV's wont have analogue RF inputs, so they won't be able to tune the really old consoles in.

And? This is also possible on Atari 8bit. when you make a list, you should not mention things that both systems can. When you compare A8 and atari ST you must compare 'bare' systems. So Atari ST without floppy (520 ST). And about harddrive. OK atari 8bit can hookup harddrive on Parallel Port and Cart Port, which is not DMA, but really fast. Fast enough I'd say. I should have realised that making a list was a mistake.... but it was so tempting Even the 520ST still has a parallel floppy interface - just no drive built in. The ST HDD interface is better because it's faster, dma, and has no low cpu cost. ( Did any of the HDD interfaces actually exist back in the day - when I was using the A8 the happy chip and US doubler were the 'cool' addons, and the cartridge port was for Mac65 ) I've seen the SIO2SD stuff ( which is still slow, but cool ) and I use the SIO2USB now - but I haven't got much knowledge about internal/cart mods.

Then again, that was in specific context of the SN76489 PSG, not the AY/YM2149, so it might be different. I'd though the 76489 used logarithmic based volume control as well ("stepped" volume rather than linear), but int hat case it's 4-bit (16 volume levels), so the YM2149 might have more control there. On the ST it was quick enough to do in an interrupt. The normal per voice volume level was {1,sqrt(1/2)}*{1,1/2,1/4,1/8,1/16,1/32,1/64,1/128} so the dynamic range was there, and the tables were precalculated to approximate a linear curve using 3 voices ( sometimes two ) I never looked at PWM for improving the signal capabilities as such, only to multiplex voices at one point ( and I've got no idea where the code is, it's probably on one of my old replay disks )

I should be programming SPE stuff at the moment ( although I think it's safe to say that it's not really required this week ) - and I've got random A8 and 7800 and Jaguar stuff in my coding folder to play with. I saw the Coco3 with the Donkey Kong and Pacman games, and the recent 256 colour pictures, but it's NTSC only which is a bit of a let down... so I'm managing to resist it.. ( and one day, maybe my Pandora console will actually arrive, and I can run the A8, C64, ST and Amiga emulators on a DS sized machine with a keyboard )

I thought they were like some of the Pern dragons in some ways

Well, on a like for like case - If I scroll a 16 colour 80x192 line screen on the ST it will take less than a quarter of the cycles ( It will also only be quarter of the screen, but that's a limitation of the A8 ) I should compare 320x192 2 colour as that's the only resolution that matches between A8 and ST. ( Also GTIA on the A8 wasn't launch, maybe I should compare an ST model with blitter for timings ) So for me: ST has 640x200 4 colour mode - better than A8 ST has 320x200 16 colour mode - better than A8 ST has 512 colours, better than 128 for launch A8 ST has faster processor - better than A8 A8 has scrolling, better than ST A8 has 4 sound channels, better than ST ST has parallel floppy disc, better than A8 ST has RGB video, better than A8 ST has DMA harddrive, better than A8 ST has 512k ram, better than A8 ... and so on, can't be bothered making a longer list ....