Rybags
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Posts posted by Rybags
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I'm fairly sure it does. I think that it is much the same as the READY line (used by WSYNC) except that internal execution still continues (I think).
But in any case, the 6502 never goes more than 2 cycles without accessing memory, so the effect is much the same.
Although, WSYNC theoretically could stop the 6502 for close to 114 machine cycles, whereas it can only lose about 96 cycles consecutively due to screen DMA (1st line of a 40-column wide-screen or h-scrolling display mode).
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Aside from MAME, there's also RAINE, Zinc, Modeller and dozens of other emulators.
http://www.retrogames.com is a good starting point for getting into arcade emulation.
Finding ROM images is another issue. There are plenty of sites around but many don't have up to date ROMs which work with later MAME builds.
I recently aquired the full MAME set, with ROMs, cabinets, flyers etc. it comes it at around 40 gig of disk space.
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I've used 2 different PC's as hosts for APE. A Pentium 200MMX and a Celeron 500.
I found that the 200 in Windows 98 was just too slow to maintain a good connection, and that tweaking settings and hitting BREAK on the Atari was the only way to get anything to load. As is mentioned in some places though, I found that the DSR setup worked better (although I made my cable myself, don't know if the premades are switchable).
Booting into command-line mode, I found APE to work great on the slower machine. Even at warp speeds, serial reception was clear and didn't require intervention at any stage.
On the Celeron 500, I found APE in Windows to work fine so far.
I only use these machines as APE hosts as I made my own cable and didn't want any risk of frying my Athlon.
I haven't played around with directly hosting files in PC directories with APE yet, so can't comment on that aspect of the system.
I feel that timing could well be an issue. Even on a fast machine it would be possible for other tasks on the PC to cause problems.
What speed PC are you using? And, how much memory and what Operating System is it running?
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Having had enough of ordinary video from the 800XL and woeful quality from my 130XE, I built an S-VHS adaptor today.
I got the parts from an electronics shop (under $6 total) and went the whole hog: S-VHS, composite video and a 3.5 mm audio plug, all running off the standard Atari monitor port.
My 800XL (as most) didn't have chroma output, so I opened up the machine and added it (attach a 100K resistor to junction of R67 and R68, then run a wire joining it to the monitor port).
Both machines show a vast improvement but still suffer some interference and the usual undesirable shadows in high contrast areas.
Next step will to build the ports into the machine.
Possible future step would be to perform the Super-video upgrade. Has anyone done these upgrades on an 800XL or 130XE PAL machine?
A site which describes the video mod: http://www.geocities.com/atarimods/index.html
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For a quick DIY PLOT X,Y routine for graphics 0, you could use a pair of tables which has the screen address of each row of characters (one for low byte, one for high). Call the INITIALIZE routine straight after opening the GRAPHICS 0 display. Call the PUTXY routine with the character code in A, and the X/Y position in registers X,Y.
; initialize the table of Y-addresses (call this routine once)
INITIALIZE LDA $58
STA ADDRL
LDA $59
STA ADDRH
LDY #0
MAKETABL LDA ADDRL
STA LOWADDR,Y
CLC
ADC #40
STA ADDRL
LDA ADDRH
STA HIGHADDR,Y
ADC #0
STA ADDRH
INY
CPY #24 ; generate 24 entries in table
BNE MAKETABL
RTS
;
ADDRL .BYTE 0
ADDRH .BYTE 0 ; temp storage
LOWADDR *=*+24
HIGHADDR *=*+24 ; reserve 2x24 byte area for tables
; store a character (passed in A, at X,Y)
PUTXY PHA ; save character
LDA LOWADDR,Y
STA ZTEMP
LDA HIGHADDR,Y
STA ZTEMP+1
TXA
TAY
PLA ; get character back
STA (ZTEMP),Y
RTS
ZTEMP = 203 ; temporary storage on zero-page for store-address pointer
[code]
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Rather than store characters on the screen, you could just use CIO, with PUT RECORD to device #0.
Using CIO is easy, download the OS manual, it has an entire chapter devoted to it.
Of course, you wouldn't want to use it for anything other than a text based game.
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Galaga has the "leave the bee alone" trick on Level 4.
I think it is the highest bee on the right, let it swoop about 57 times (until it stops firing). From then on, the game is a cakewalk as no aliens fire at you.
Doing that trick also reveals the "Stage 256 bug", where the machine finishes Level 255 then crashes and restarts.
Defender had the "International Date Line" trick, where if you were being chased and crossed a certain part of the landscape, the enemy would turn around and chase you from the opposite direction.
Rygar has a few (some intentional). If you don't have the bear power-up (destroys enemies by landing on them), you can ride the big birds to the end of a level by jumping on them.
Hidden 1 million in Stage 13. (repeatedly shoot near the rightmost star when several of them appear near the tree about 1/2 way through the level).
Bonus 10,000 at end of stage. Finish a level and hold the stick down/left. If the time remaining matches the hundreds component of your score, you get 10,000 points. Easiest way to get it is just let the time run to 00, and make sure your score is xxx000-xxx090.
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I somehow managed to damage the internal power supply of my Atari 400 over 20 years ago. Luckily, I got it fixed for free by a friends father.
I managed to fry a TNT2 with TV-out by plugging it in to the VCR. Luckily it was still under warrantee and got replaced the same day.
Worst story: I simultaneously touched the metal shaft of my Wico joystick and Amiga montior and zapped the system. Now that computer thinks that the joystick is permanantly pushed forward.
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SuperDOS was packaged with a locally developed "poor-man's Happy Board" which was a turbo-upgrade for the 1050 drive, but without the features which allowed reproduction of copy protection schemes.
I'm fairly sure the company that made them was based in Queensland.
They also developed "SuperMON" which was an OS with built-in monitor (like OmniMon). I think they might also have developed "SuperRAM" for the 400/800 which allowed bank-selecting an extra 16K, mapped at $C000-$CFFF.
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I transferred some of my old stuff recently too.
I've been amazed that most of my disks are near perfect, but 2 possibilities if you get a disk that's got read errors:
- pull the 1050's cover off and give the R/W head a clean. A cotton bud or lint-free cloth with video head cleaner does the trick.
- some floppies become warped or the jacket gets damage which impedes the disk spinning. I had one disk that I just removed from the jacket. Then, you can either put it in another jacket, or manually insert it into an opened up disk drive.
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The "official" DVD specifications allow for a maximum bitrate of 9800 Mbps for video + whatever the audio requires (max=320 kbps in AC3?), which equates to around 10 Megabits/second.
I've authored DVDs with a much higher rate which play fine in my STB, but older players might have trouble with them.
Thanks for the info, Damagex.
The major reason for better color representation from PAL is in the name "Phase Alternating Line".
PAL chroma information is phase inverted on each alternating line, and a delay circuit is used to feed the information back so that two signals are available. The signals are then averaged to create the outputted color.
For that reason, no PAL TV has, or requires a manual hue control.
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If you could get hold of an Amiga modulator it would probably work, but would involve making a custom cable.
Or, an Amiga monitor could be a possibility.
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Most modern TVs will do PAL or NTSC, thanks to digital electronics.
PAL is superior in the vertical resolution area. I've set my TV-out to NTSC and it just looks plain inferior on a TV.
But, NTSC has a slight advantage by having 60 Hz refresh, although on most TVs you can't tell the difference.
PAL60 is an unofficial mode, supported by some TVs and graphics hardware, it combines the refresh of NTSC with the resolution of PAL.
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An external modulator would be fine. Worth checking if it's got a composite option though.
Or, do a web search and see if there are any S-VHS out projects around. It would be a better option if your VCR or TV has S-VHS input.
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The only way to do it is with the machine on.
Just be sure to run something like the 256 color program above, and remember the initial setting in case you can't get one you like.
From what I've read, the trimmer just sets the delay for the color signal, which would make the colors just rotate around the colorspace.
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The SMS sticks don't use pots for triggers. Just like the ST mouse, it uses the paddle input.
Technically, there is nothing wrong with that. It would just mean reading the paddles in fast potgo mode, which would take a dozen lines of code.
In any case, the XBOX uses pots for it's shoulder buttons, and I haven't heard any complaints about that.
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Strange. There was an STF model without modulator.
Does the sticker on the top have the small "FM" letters after "ST"? And does either sticker look like it's been replaced?
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Screencaps from my 2 machines.
There's some major RFI happening here. Possibly because I have 3 computers running.
I got an almost unreadable display plugging directly into my capture card, so I had to run the 2 Ataris through the VCR. From there, it's a 30 foot journey through RCA leads, and capture in composite input mode.
The 800XL is a bit washed out and the 130XE is still copping some major interference.
Screen was generated in Graphics 9, all default settings. Colors 0 thru 15, with 1 color 0 pixel width between the bars.
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I'll try and get those screen caps a bit later.
No idea if PAL XL matches PAL 2600, but I am led to believe that the PAL 2600 are also different to NTSC models in that regard.
PAL color 3 is a fairly pure red, it always mystified me why so many games used color 4. It has virtually no hint of red in my observation (other than that obviously needed to mix with blue to achieve violet/purple).
One suggestion: if your machine has the color trimmer adjustment (underneath, accessable from outside on the 800XL), you could try adjusting it. Do it while you have your color demo proggie running.
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Definately the XL.
It's surprised me that people haven't been converting games to use >1 fire button.
The Sega Master System used Atari control ports, and their gamepad had an extra button (like the ST mouse, the extra button/s can use the paddle inputs).
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I co-authored a book of games (More Games for Your Atari 600XL) in 1983/84.
I also wrote a game on the C-64 which appeared in someone elses book, and 3 others which were in their own book "Astounding Arcade Games for the Commodore 64" in 1984.
I worked for a software house doing BASIC/ASM educational software for the C-64 in 1986 (the company went under).
I made a 1050 emulator + LPT cable adaptor on the ST around 1989, in DBASIC/68K Assembler. Never developed it beyond a home project though.
Heaps of industry experience on mainframes, I'm qualified as an IBM OS/390 Systems Programmer.
Biggest programming project there were an accounting system for a database, which was around 6,000 lines of code which took about 10 weeks to write.
I successfully worked out the technique for "Sprites in the border" on the Commodore 64 on my own after seeing it in a game.
I also devised a method for doing glitch-free split-screen scrolling on that machine (most split screen games have nasty flickering in the transition areas).
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Is it a PAL or NTSC Atari?
PAL Ataris are different. It is well known that Color 1 and 15 are virtually identical on PAL Ataris.
Color 4 on PAL is also violet/purple. I think it should be more reddish, although I haven't seen a live NTSC machine.
I have both an 800XL and 130XE and have owned the 400 and 600XL. Aside from the complaint of display quality being progressively worse in the newer machines, the colors were the same in all of them.
If I get time later, I'll do some screen caps from a real machine.
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AFAIK, no official Atari 8 bit cartridges required a specific format.
Most games for computers such as the Atari, C=64 and Atari ST work fine on either system.
Demos are really only a special case if they use a full display. That can cause problems on NTSC, either/both with the display going outside what the TV can show, or the machine not having enough cycles to be able to frame render quick enough.
PAL machines have around 35,500 cycles per frame, NTSC only gets29,900.
Almost all Atari 8-bit games base their movement/rendering on the VBlank interval so the only side effect will be that games will play slower on PAL.
I've never come across a piece of software that won't work on PAL. The only ones I've heard of having problems are certain hardware turbo-disk accelerators.
A final note is that sound on PAL is slightly different (lower pitch), but barely detectable in most cases.
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Should be fine. In most cases, the only difference is less speed on PAL systems for games.
I have it on .ATR image, but haven't tried it on my PAL XL or XE.
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[LePix] Assembler Question
in Atari 8-Bit Computers
Posted
That code looks a bit over-complicated.
Why not just add your offset, then use the following code to correct out-of bounds conditions:
That code is a bit over-complicated too, but you can't just AND out the high bits of the cursor position, as the wrap-around won't work properly.