A 600XL puzzle

[MAC-42]

Here's a puzzle for you folks to chew on.

 

I picked up an as-is 600XL on the Evil Bay. It arrived, and I glanced askance at the Ingot power supply as I unpacked it. I connected it using the good PS from my XEGS and turned it on. All that came up was a black screen with nine vertical bars on the left side of the screen. No BASIC, so I grabbed my Pac-Man cart. Same result. On a whim, I stuck my Star Raiders cart in, and the thing came to life. The keyboard seems to work. The joystick button works, but the stick itself is non-responsive. Sounds were okay, by the way. I don't have a BASIC cart so I can't see what happens as far as loading it at all. Finally, I tried to connect my SIO2PC to boot a DOS from a PC, but without result. The Atari didn't respond to the SIO2PC.

 

I'm worried that the Ingot cooked some stuff in this Atari under a previous owner's ownership. I'd be willing to take a stab and guess that the PIA is shot based on the joystick issue. (Does PIA handle input from the SIO? I was trying to read the schematic in the midst of trying to put three screamin' little girls to bed.). POKEY seems fine, as, I guess, does ANTIC and GTIA.

 

Anyway, all of that ramble to ask if anyone can tell me why one cart would work and one won't. That's what has me scratching my head. Any ideas? Thanks.

[+MrFish]

The Star Raiders cart runs in diagnostic mode -- as does Asteroids, I believe.

[atari8warez]

I'd be willing to take a stab and guess that the PIA is shot based on the joystick issue. (Does PIA handle input from the SIO?

 

Pin 19 (CB2) of PIA controls the SIO Command Line (SIO7). So I'd say if PIA is bad SIO will not work either. PIA also controls SIO Proceed/Motor Control and Interrupt lines but none of those signals are used by Atari disk drives or SIO2PC (the only exception that i know off is my SIO2PC/10502PC combo which uses the Proceed line to determine whether it is connected to an Atari computer or an Atari disk drive)

 

You can check the voltage levels on SIO7 if you have a multimeter, a healthy pin should read close to 5v.

Edited June 5, 2014 by atari8warez

[russg]

Here's a puzzle for you folks to chew on.

 

I picked up an as-is 600XL on the Evil Bay. It arrived, and I glanced askance at the Ingot power supply as I unpacked it. I connected it using the good PS from my XEGS and turned it on. All that came up was a black screen with nine vertical bars on the left side of the screen. No BASIC, so I grabbed my Pac-Man cart. Same result. On a whim, I stuck my Star Raiders cart in, and the thing came to life. The keyboard seems to work. The joystick button works, but the stick itself is non-responsive. Sounds were okay, by the way. I don't have a BASIC cart so I can't see what happens as far as loading it at all. Finally, I tried to connect my SIO2PC to boot a DOS from a PC, but without result. The Atari didn't respond to the SIO2PC.

 

I'm worried that the Ingot cooked some stuff in this Atari under a previous owner's ownership. I'd be willing to take a stab and guess that the PIA is shot based on the joystick issue. (Does PIA handle input from the SIO? I was trying to read the schematic in the midst of trying to put three screamin' little girls to bed.). POKEY seems fine, as, I guess, does ANTIC and GTIA.

 

Anyway, all of that ramble to ask if anyone can tell me why one cart would work and one won't. That's what has me scratching my head. Any ideas? Thanks.

I don't know much. But the 600XL isn't going to boot DOS, I don't think because it is 16K, just enough RAM to run a 16k cart. I do believe that you should get some action on the SIO2PC when

you power on, but without LEDs (like in an APE interface), you aren't going to know.

[MAC-42]

Thanks, folks, for your thoughts on this. My XEGS has run like a top for a year or so now, so this is all new territory for me. I've read about others' problems before, but never had to face them down myself.

 

The Star Raiders cart runs in diagnostic mode -- as does Asteroids, I believe.

You know, now that you mention it, I've seen this mentioned before. That might go a long way in explaining it, mightn't it? Thanks.

 

 

Pin 19 (CB2) of PIA controls the SIO Command Line (SIO7). So I'd say if PIA is bad SIO will not work either. PIA also controls SIO Proceed/Motor Control and Interrupt lines but none of those signals are used by Atari disk drives or SIO2PC (the only exception that i know off is my SIO2PC/10502PC combo which uses the Proceed line to determine whether it is connected to an Atari computer or an Atari disk drive)

 

You can check the voltage levels on SIO7 if you have a multimeter, a healthy pin should read close to 5v.

I'll have a look at the SIO port tomorrow. (Didn't realize that my multimeter is sitting here right on my desk in front of me all evening long. It's been a long, long day.) Thanks for pointing this out. Narrows down at least one problem with this machine, most likely.

 

I don't know much. But the 600XL isn't going to boot DOS, I don't think because it is 16K, just enough RAM to run a 16k cart. I do believe that you should get some action on the SIO2PC when

you power on, but without LEDs (like in an APE interface), you aren't going to know.

 

Is that right about the DOS? I'm so spoiled living with 64k that it never really occurred to me whether a DOS would run on 16k. I'll have to bear that in mind. Assuming I can noodle out what the rest of the problems with this thing might be and actually repair them.

[Joey Z]

Thanks, folks, for your thoughts on this. My XEGS has run like a top for a year or so now, so this is all new territory for me. I've read about others' problems before, but never had to face them down myself.

 

You know, now that you mention it, I've seen this mentioned before. That might go a long way in explaining it, mightn't it? Thanks.

 

I'll have a look at the SIO port tomorrow. (Didn't realize that my multimeter is sitting here right on my desk in front of me all evening long. It's been a long, long day.) Thanks for pointing this out. Narrows down at least one problem with this machine, most likely.

 

 

Is that right about the DOS? I'm so spoiled living with 64k that it never really occurred to me whether a DOS would run on 16k. I'll have to bear that in mind. Assuming I can noodle out what the rest of the problems with this thing might be and actually repair them.

if you get a black screen on normal bootup, then it's likely that it isn't even attempting to load from SIO. I don't think it's very likely that a bad PIA alone would cause the problems you are having, but I suppose it's possible. You do almost definitely have a bad PIA though, so replace it and see what happens.

 

Also, you shouldn't immediately assume that the ingot killed it. You should check it with a multimeter. It should be 5v +/- 5%. if it's good, then it's not too likely the ingot killed the atari. That means it could be other issues still, like bad connections. You can try reseating the PIA if it's socketed, and see what happens. It's not uncommon for the Atari OEM sockets to build up oxidation, and reseating the chip a few times might solve the problem if that is the case.

 

EDIT: Did you try running self test? I doubt it will run, but it's best to know for sure rather than assume.

Edited June 5, 2014 by Joey Z

[+bob1200xl]

A 600XL will boot DOS 2.0 with almost 7K of memory left.

 

Using a diagnostic cart like Star Raiders circumvents all the system tests that occur very early in the power-up sequence. If you leave the cart out, one of the first things that should happen is to initialize the hardware. This will clear the screen and turn 'off' ANTIC. If this is not happening, you have a low-level failure. Memory does not need to work, nor do most of the other support chips.

 

This is probably an MMU failure (U2).

 

Bob

[russg]

A 600XL will boot DOS 2.0 with almost 7K of memory left.

 

(snip)

Bob

Thanks for answering that. DOS.SYS is 4992 bytes (39*128) and loads at $700 to $1A80 ( 1792 to 6784) I think. The 600XL has RAM to $4000 (16K). DUP.SYS loads

5114 bytes at $1F0C to $3305 (7948 to 13061) and runs at $2075. So a 16K 600XL can not only load DOS.SYS but also can run DUP.SYS. It has BASIC built in

so it can save BASIC programs.

I had a friend many years ago that had a 600XL. I took a floppy drive over and tried to boot DOS and it failed, so that's where I got the idea it was insufficient memory.

I guess now that the 600XL had some defect. (I'm talking about DOS 2.0S) addresses and sizes may not be right, 39 sectors only has about 125 useful bytes per sector,

the rest are file sector links.

Edited June 6, 2014 by russg

[MAC-42]

if you get a black screen on normal bootup, then it's likely that it isn't even attempting to load from SIO. I don't think it's very likely that a bad PIA alone would cause the problems you are having, but I suppose it's possible. You do almost definitely have a bad PIA though, so replace it and see what happens.

 

Also, you shouldn't immediately assume that the ingot killed it. You should check it with a multimeter. It should be 5v +/- 5%. if it's good, then it's not too likely the ingot killed the atari. That means it could be other issues still, like bad connections. You can try reseating the PIA if it's socketed, and see what happens. It's not uncommon for the Atari OEM sockets to build up oxidation, and reseating the chip a few times might solve the problem if that is the case.

 

EDIT: Did you try running self test? I doubt it will run, but it's best to know for sure rather than assume.

That's a good point about SIO not even being looked at by the computer if it's booting badly. Didn't think about that. Trust me to put the cart before the horse. It's been a really rough couple of days so I haven't been able to take the multimeter to the SIO port as I had planned, let alone the PSU, but I can do that in a little bit.

 

I tried loading the self test, but as you thought, it won't respond.

 

A 600XL will boot DOS 2.0 with almost 7K of memory left.

 

Using a diagnostic cart like Star Raiders circumvents all the system tests that occur very early in the power-up sequence. If you leave the cart out, one of the first things that should happen is to initialize the hardware. This will clear the screen and turn 'off' ANTIC. If this is not happening, you have a low-level failure. Memory does not need to work, nor do most of the other support chips.

 

This is probably an MMU failure (U2).

 

Bob

So, if I'm understanding correctly, plugging in Star Raiders and getting a result will eliminate a few possible points of failure and we can be pretty sure that chips like ANTIC and the RAM are all right. (The RAM is not a big deal as I was planning to perform an upgrade in any case.) That's interesting as I was kind of treating this whole thing as a post-mortem until now.

 

Thanks for all of the useful information, everybody. This is, as I say, kind of new ground to me. Having to deal with this practically adds a dimension to the stuff I've read.

[RodLightning]

Thanks for all of the useful information, everybody. This is, as I say, kind of new ground to me. Having to deal with this practically adds a dimension to the stuff I've read.

 

Ditto. Good subject. I'm getting a Star Raiders cart as a direct result of this thread. It's a cool game either way.

 

Besides Asteroids, how may other cartridge titles run in diagnostic mode?

[russg]

Thanks for answering that. DOS.SYS is 4992 bytes (39*128) and loads at $700 to $1A80 ( 1792 to 6784) I think. The 600XL has RAM to $4000 (16K). DUP.SYS loads

5114 bytes at $1F0C to $3305 (7948 to 13061) and runs at $2075. So a 16K 600XL can not only load DOS.SYS but also can run DUP.SYS. It has BASIC built in

so it can save BASIC programs.

I had a friend many years ago that had a 600XL. I took a floppy drive over and tried to boot DOS and it failed, so that's where I got the idea it was insufficient memory.

I guess now that the 600XL had some defect. (I'm talking about DOS 2.0S) addresses and sizes may not be right, 39 sectors only has about 125 useful bytes per sector,

the rest are file sector links.

I know what happened. I was using SpartaDOS 3.2d. That DOS won't run in 16K, I think. I know MyDOS 4.53 won't run in 16K. Well, I think I was trying Sp 3.2d.

DOS 2.0S and 2.0d will load in 16K. And will run on 800/400. SpDOS won't run on 400/800. Well, disk based SpDOS, I guess SpX cart versions will run 400/800.

[BillC]

I know what happened. I was using SpartaDOS 3.2d. That DOS won't run in 16K, I think. I know MyDOS 4.53 won't run in 16K. Well, I think I was trying Sp 3.2d.

DOS 2.0S and 2.0d will load in 16K. And will run on 800/400. SpDOS won't run on 400/800. Well, disk based SpDOS, I guess SpX cart versions will run 400/800.

Disk based SpartaDOS 1.x(original disks have purple label) does run on the 400/800, I don't know whether it will run with only 16K though.

[MAC-42]

Giving this post a nudge up for information's sake. I finally got around to ordering the PIA chip and, just in case, the MMU chip that bob1200xl suggested I look into. I just replaced the PIA--thank goodness for those sockets--and, for giggles, decided to see if that, at least, fixed my Star Raiders joystick problems before moving on to the MMU chip. (I tried unseating and reseating the PIA as Joey Z suggested above to no effect, unfortunately.) As usual, Star Raiders loaded, but this time I had full joystick functionality. One problem down.

 

I decided to pull Star Raiders out and fire it up again without the new MMU, however, because I accidentally bumped the power switch before plugging in the cart the first time around and saw a cursor. I hit the switch and let it load to a READY prompt. I was, sure enough, booted into BASIC. It appears that the PIA was in fact bad, and that the bad PIA was in fact preventing the machine from booting up.

 

Just thought I'd pass that on to posterity and those of you good folks who helped me out with this. Thanks again for your information and assistance!

 

And boy, do I love cheap fixes!