Are 800XL's less stable than 65/130 XE's?

[Bryan]

Interleaving CPU and DMA access is a neat trick, but on both the Apple and the C64 it meant a 1MHz CPU since it creates two RAM cycles for each CPU cycle. Atari's more textbook method of running the RAM and CPU at the same (higher) speed gave you access to more CPU power, but less predictable timing (which is why DLISTS and WSYNC are so important). Even with all the DMA going on, the Atari is still the fastest machine.

 

The Apple slot system was very useful, but the expandable chassis had FCC issues and could not be certified as a TV compatible device. Atari engineers have stated that they wanted open slots, but had to encase the whole thing within the computer to pass FCC tests. Apple drives are fast because they are on the system bus, but the simple controller-less interface means the CPU is completely tied up during loads (which, I admit, is usually not a problem). Woz kept the Apple's design so simple that it didn't need custom ASICs, but the price was still through the roof. I think Atari did a better job of designing for the home market, but a much worse marketing job.

 

So, I also value the Apple II but it's a statement in minimalism. Only someone as clever as Woz could have created a capable home computer (and indeed, an industry) without a huge initial investment. When Atari entered the computer game (and while the engineering team was intact), Atari represented cutting-edge engineering but clueless leadership.

Edited August 21, 2010 by Bryan

[MEtalGuy66]

Interleaving CPU and DMA access is a neat trick, but on both the Apple and the C64 it meant a 1MHz CPU since it creates two RAM cycles for each CPU cycle. Atari's more textbook method of running the RAM and CPU at the same (higher) speed gave you access to more CPU power, but less predictable timing (which is why DLISTS and WSYNC are so important). Even with all the DMA going on, the Atari is still the fastest machine.

In what respect? Player/missile animation? Not raw number crunching.. The apple shits all over it on exact equivelant 6502 code, unless you turn off ANTIC, in which case the ATARI does beat it, but not nearly by as much as you'd expect.. (Please remember, I have been on the ATARI side of this argument for about 26-27 years now.. I alwayse had an ATARI and My Brother was an Apple guy.. These days, he's part of a chip design team and writes firmware for internal diagnostic tests on new communications procesors.. The company he works for is called Legerity.. It's a spinoff of AMD.) So we have "been there and done that" where the metal actually hits the pavement... MANY times.. Growing up, I dont think either of us would have made the career choices we did, if there hadnt been such fierce competition in the house between "The Apple Guys" and the "Atari Guys".. Go get a real APple, and do the test yourself.. I Know from far too many experiences that I'm 100% right... Only way I could shut him up is by loading up a Demo or game that had decent sound, lots of colors, and smooth animation.. And then he'd bitch about the (comparatively) long load-times..

 

The Apple slot system was very useful, but the expandable chassis had FCC issues and could not be certified as a TV compatible device.

You have got to be shitting me.. heh.. The FCC's requirements in the 80s were rediculous.. The video circuits in the XL/XE series suck total ass by ANY DECENT analog/RF circuit designer's standards.. They were designed primarily to be cheap, but on top of that, they just made real sloppy choices on many key aspects of the video output circuits.. Ever seen all the various "Video tune-up" hacks out there? They make a huge improvement by just correcting the "way off in left field" component values, simple power distribution/rf induction issues, etc.. Apple on the other hand, as I recall, had a prestine ass picture on TV if you bought their external RF modulator box, had great composite color output with no smearing or vertical "ghosting" (which is also more than I can say for most stock XL/XE machines) and actually did a damn clear 80 columns (7bits per char), even on a color monitor.. They had the sense to tunr off the chroma component of the composite signal when outputting 80 columns for productivity software, and that made all the difference.. You could turn it back on in software (hence double hi-res modes) if you wanted twice as many colors in hi-res..(or twice the horizontal color clocks anywayze.)

Atari engineers have stated that they wanted open slots, but had to encase the whole thing within the computer to pass FCC tests.

My guess is that the original XL/XE prototype designs were probably decent, but they might have been "revised" to meet low targetted production costs and rediculous FCC standards.. Possibly, whoever did the "revisions" was not the best in the world, and was probably rushed by management..

 

Apple drives are fast because they are on the system bus, but the simple controller-less interface means the CPU is completely tied up during loads (which, I admit, is usually not a problem).

Dude.. The atari doesnt have a dedicated processor for disk access either... The CPU has to take all the data from pokey and move it to appropriate places in memory.. Apple's VERY REAL disk controller chip which is located on the motherboard of every Apple II, is not a standalone processor either.. But the Apple doesnt have to go through the extra layer of crap to convert everything to serial and send it over a (comparatively) slow assed 19.2k - 57k connection, and then have very little low level control of the chips that actually ARE manipulating the drive, as is the case with ATARI..

Woz kept the Apple's design so simple that it didn't need custom ASICs, but the price was still through the roof. I think Atari did a better job of designing for the home market, but a much worse marketing job.

The Apple II does use LSI chips for it's Display, Disk Access, etc.. And if they didnt have them made, I dont know who did, because they are damn sure proprietary as hell.. No subsystem of the machine has it's core logic built simply out of discrete TTL logic ICs, as you seem to suggest.

 

So, I also value the Apple II but it's a statement in minimalism. Only someone as clever as Woz could have created a capable home computer (and indeed, an industry) without a huge initial investment. When Atari entered the computer game (and while the engineering team was intact), Atari represented cutting-edge engineering but clueless leadership.

True.. Though I can think much more minimalistic systems from the same era the Apple II was made, and later...

[Bryan]

In what respect? Player/missile animation? Not raw number crunching.. The apple shits all over it on exact equivelant 6502 code, unless you turn off ANTIC, in which case the ATARI does beat it, but not nearly by as much as you'd expect..

 

Umm.. The Atari is 1.79MHz vs 1.0 for the Apple. For the Atari to be slower than the Apple it would need to lose 45% of its cycles to DMA, which never happens.

 

You have got to be shitting me.. heh.. The FCC's requirements in the 80s were rediculous.. The video circuits in the XL/XE series suck total ass by ANY DECENT analog/RF circuit designer's standards..

 

You totally missed my point. Apple's case kept them from selling it as a consumer TV device (in other words they were forbidden from selling it with a modulator and had to offer a monitor). It was central to Atari's plan that you be able to use your own TV, so they couldn't use an easily expandable case like Apple's. The standards were later relaxed.

 

Dude.. The atari doesnt have a dedicated processor for disk access either... The CPU has to take all the data from pokey and move it to appropriate places in memory.. Apple's VERY REAL disk controller chip which is located on the motherboard of every Apple II, is not a standalone processor either.. But the Apple doesnt have to go through the extra layer of crap to convert everything to serial and send it over a (comparatively) slow assed 19.2k - 57k connection, and then have very little low level control of the chips that actually ARE manipulating the drive, as is the case with ATARI..

 

Atari drives have a Western Digital disk controller, an on-board CPU, and then are slowed down by the SIO bottleneck. Apple's have a very simple drive-to-bus interface that requires the main CPU to do the grunt work of decoding the raw data stream (see picture). It was very cheap and fast but had no controller.

 

The Apple II does use LSI chips for it's Display, Disk Access, etc.. And if they didnt have them made, I dont know who did, because they are damn sure proprietary as hell.. No subsystem of the machine has it's core logic built simply out of discrete TTL logic ICs, as you seem to suggest.

 

You've never seen an old Apple II, have you? It's a sea of TTL logic with a few big 65XX MOS chips and ROMs in there. Only later Apple II's had custom logic to make small machines like the IIc possible. Atari's designs would never have fit if done discretely.

[MEtalGuy66]

Yeah I have.. I actually have a working IIe motherboard, complete with floppy controller, paralell card, super serial card, 80 column/128k card, etc. on a shelf somewhere.. One of my neighbors literally THREW the computer out to the curb and the case & keyboard was pretty trashed, so I salvaged the guts and threw away all the broken stuff. One day I'll find a burned out IIe to fix with it..

 

But yeah, you got a point.. I was thinking of the IIc where they integrated all that into a single chip.. But same thing, electronically. ANywayze, if you ask me, I'll take super fast load times over the ablity to play complex content DURING disk access any day.. I was alwayse jealous of how fast & reliable Apple's disk system was..

 

ATARI's SIO bus is slow, noise prone, and much less stable, overall.. NTSC XF551s usually do not even work 100% error free with NTSC 130XEs until you remove the "FCC filters" from the SIO bus on the 130xe. Freakin rediculous. I guess that was all in the name of being able to market it as a "TV Appliance" like you suggest..

 

It'd be kewl as hell to take that Disk II controller card and use it as the basis for a small PBI board.. With custom firmware in ROM on the card..

[Divya16]

Yeah I have.. I actually have a working IIe motherboard, complete with floppy controller, paralell card, super serial card, 80 column/128k card, etc. on a shelf somewhere.. One of my neighbors literally THREW the computer out to the curb and the case & keyboard was pretty trashed, so I salvaged the guts and threw away all the broken stuff. One day I'll find a burned out IIe to fix with it..

 

But yeah, you got a point.. I was thinking of the IIc where they integrated all that into a single chip.. But same thing, electronically. ANywayze, if you ask me, I'll take super fast load times over the ablity to play complex content DURING disk access any day.. I was alwayse jealous of how fast & reliable Apple's disk system was..

 

ATARI's SIO bus is slow, noise prone, and much less stable, overall.. NTSC XF551s usually do not even work 100% error free with NTSC 130XEs until you remove the "FCC filters" from the SIO bus on the 130xe. Freakin rediculous. I guess that was all in the name of being able to market it as a "TV Appliance" like you suggest..

 

It'd be kewl as hell to take that Disk II controller card and use it as the basis for a small PBI board.. With custom firmware in ROM on the card..

 

Fortunately, Atari already had a faster way to read in data/programs-- it's called a cartridge. That's what I use. Disk drives were slow but nowadays you can see the potential of POKEY with those warp speed simulated drives. Apple II is only respected because it came earlier-- it's inferior in everything to Atari as far as I can tell. I played some digitized audio demos on A8 and Apple one sounds all crappy and noisy so whatever those DMA cycles are, the programmers knew how to deal with them. Even Berzerk audio is crystal clear. I think you are just making things up-- you really think Atari was selling stuff was noise prone and unstable. Don't you think it would have failed the quality assurance and be headlines given the cut-throat competition in those days? I seriously think you lost this debate.

[Rybags]

Practically all the early Atari speech/digitized stuff was crap.

 

They used delay loops instead of timers or VCount based waits in almost all cases, plus it worked poorly with the screen enabled.

 

Modern day times... we know how to cope with all that stuff now - just look at the virtual multi-channel stuff for GTIA Consol sound as an example.

[Bryan]

Yeah I have.. I actually have a working IIe motherboard, complete with floppy controller, paralell card, super serial card, 80 column/128k card, etc. on a shelf somewhere.. One of my neighbors literally THREW the computer out to the curb and the case & keyboard was pretty trashed, so I salvaged the guts and threw away all the broken stuff. One day I'll find a burned out IIe to fix with it..

 

But yeah, you got a point.. I was thinking of the IIc where they integrated all that into a single chip.. But same thing, electronically. ANywayze, if you ask me, I'll take super fast load times over the ablity to play complex content DURING disk access any day.. I was alwayse jealous of how fast & reliable Apple's disk system was..

 

ATARI's SIO bus is slow, noise prone, and much less stable, overall.. NTSC XF551s usually do not even work 100% error free with NTSC 130XEs until you remove the "FCC filters" from the SIO bus on the 130xe. Freakin rediculous. I guess that was all in the name of being able to market it as a "TV Appliance" like you suggest..

 

It'd be kewl as hell to take that Disk II controller card and use it as the basis for a small PBI board.. With custom firmware in ROM on the card..

 

You'd probably need a local CPU as well to get the accurate timing needed. That's pretty much what's in a C= 1541. It also does GCR decoding with a 6502 instead of MFM with a controller. Why not just put a WD controller on a PBI board? It relaxes the timing over polling for flux changes and you could use a circuit like the one in the 1450XLD.

[Bryan]

Practically all the early Atari speech/digitized stuff was crap.

 

They used delay loops instead of timers or VCount based waits in almost all cases, plus it worked poorly with the screen enabled.

 

Modern day times... we know how to cope with all that stuff now - just look at the virtual multi-channel stuff for GTIA Consol sound as an example.

The Apple could do remarkable digital stuff with that 1-bit speaker due to having deterministic timing loops. Of course, it was tough to make it do much else if you wanted decent sound. I think having 4-voice in-game music is much nicer.

[+bob1200xl]

I tried to PBI a WD2797 on the 1200XL - can't be done. (yeah, OK... with DMA you can) You have data being read from the disk that will not tolerate -HALT cycles at the 'wrong' time. You get this burst of data and then a pause where you overran the buffer, then more data.

 

The 1450XLD uses an 8039 CPU to run the disk drives. The Floppy Board has a processor, also. (I think)

 

One of my early projects was a parallel interface from a 1050 to the Atari. That worked pretty well but was not PBI so it ate up a lot of resources. Doing one on the PBI would be more useful.

 

Bob

 

 

 

Yeah I have.. I actually have a working IIe motherboard, complete with floppy controller, paralell card, super serial card, 80 column/128k card, etc. on a shelf somewhere.. One of my neighbors literally THREW the computer out to the curb and the case & keyboard was pretty trashed, so I salvaged the guts and threw away all the broken stuff. One day I'll find a burned out IIe to fix with it..

 

But yeah, you got a point.. I was thinking of the IIc where they integrated all that into a single chip.. But same thing, electronically. ANywayze, if you ask me, I'll take super fast load times over the ablity to play complex content DURING disk access any day.. I was alwayse jealous of how fast & reliable Apple's disk system was..

 

ATARI's SIO bus is slow, noise prone, and much less stable, overall.. NTSC XF551s usually do not even work 100% error free with NTSC 130XEs until you remove the "FCC filters" from the SIO bus on the 130xe. Freakin rediculous. I guess that was all in the name of being able to market it as a "TV Appliance" like you suggest..

 

It'd be kewl as hell to take that Disk II controller card and use it as the basis for a small PBI board.. With custom firmware in ROM on the card..

 

You'd probably need a local CPU as well to get the accurate timing needed. That's pretty much what's in a C= 1541. It also does GCR decoding with a 6502 instead of MFM with a controller. Why not just put a WD controller on a PBI board? It relaxes the timing over polling for flux changes and you could use a circuit like the one in the 1450XLD.

[atariksi]

DMA cycles are also deterministic given the graphics mode. Only text mode, you have a high latency with consecutive DMA cycles. In graphics mode even with if you take control on a DMA cycle, the next will be free almost 100% of the time. So audio doesn't suffer in graphics mode and you can guarantee avoiding latency by cycle-exact stuff, but even with the one cycle latency hit, that's like running 900Khz..1.79Mhz. It's more optimal to use DMA and run at almost twice the speed than avoid DMA cycles and run at half the speed. Also, the DMA cycles are mostly under your control using a display list. Amiga is also using whole bunch of DMA cycles for different stuff yet it outperforms Mac/Atari ST even with slightly higher processor speeds.

[MEtalGuy66]

 

Fortunately, Atari already had a faster way to read in data/programs-- it's called a cartridge. That's what I use. Disk drives were slow but nowadays you can see the potential of POKEY with those warp speed simulated drives. Apple II is only respected because it came earlier-- it's inferior in everything to Atari as far as I can tell. I played some digitized audio demos on A8 and Apple one sounds all crappy and noisy so whatever those DMA cycles are, the programmers knew how to deal with them. Even Berzerk audio is crystal clear. I think you are just making things up-- you really think Atari was selling stuff was noise prone and unstable. Don't you think it would have failed the quality assurance and be headlines given the cut-throat competition in those days? I seriously think you lost this debate.

 

Dude, I hate to break this to you.. The absolute FASTEST "ultraspeed POKEY hack" does not even come close to the speed of a stock Apple II disk drive.. If you have ever used ADT on the apple to transfer disk images from the PC to real floppies on the Apple, you'll notice that the disk drive has no problem "out running" the serial port, even at 115kbps.. It will make an entire 140k disk from the PC in a little over 30 seconds..

 

But as we already discussed, its not even fair to compare the two.. One (apple) has the obvious speed/control advantage, while the other (atari) has the advantage of scalability of the bus, and much lower CPU resource requirements. This is due to vast differences in design/implementation.

 

Apple's disk drives are controlled/accessed similar to the way that hardisks are controlled/accessed on the ATARI.. But as Bryan pointed out, its a very rudimentary interface, hardware-wise.. And very limited as far as what you can hook up to it.. Two disk drives is about it..

 

MyIDE probably a really good comparisson.. It's fast as hell.. ANd the hardware layer of the interface is virtually non-existant.

[Bryan]

There's an article out there on the interwebz (ah yes, Wikipedia mentions it: http://en.wikipedia.org/wiki/Group_code_recording) which discusses how the different versions of Apple DOS actually have different GCR encodings, something you could never do unless you have CPU-based decoding.

 

The copy protections that were possible on Apple and C= drives were insane. You can make up your own track formatting, sector sizes, data encoding, etc... Atari's protection methods couldn't go much beyond seeing how the controller responded to malformed data (oh, and I guess there were a few tricks related to rotational and step speed).

 

The fact that the 1541 can load extremely quickly under software control makes it such a crime that they released it the way they did.

[Kylev]

Just as an anecdotal statement, I bought my first Atari (an 800XL) in 1983 and upgraded it to 256K in either 1984 or 1985. I used that computer consistently until about 1996 for everything from writing reports to playing games and never experienced any problems with stability of the system. I think I would say that the 800XL is a stable platform. I cannot compare the 130XE to it because I only used my 130XE for a few years, not the 13 years for the 800XL.

 

Russ