800XL Startup Problem

[Daedalus2097]

Hi all,

I recently rescued my old Atari 800XL from my parents' attic and wanted to give it a whirl. It's just a base unit with an XC12 cassette deck, bust I spent a huge amount of time on it when I was a kid, both playing games and programming. I connected it up and was delighted to find that familiar blue screen looking at me!

 

However, it does not seem to be able to read data from the tape deck. In fact, having the tape deck even attached seems to affect the startup of the computer - with nothing attached to the SIO port, it starts up as normal. With the cassette deck attached however, the little noise before READY appears is different and much faster. I don't know what the purpose of that clicky noise is between the blue screen appearing and READY appearing, but having the tape deck attached affects it where it never used to back when I used it regularly.

 

Anyone have any ideas what might cause this? I'm pretty good technically, but most of my retro experience is repairing Amigas - I don't have any experience with the Atari at all, so any pointers as to where the fault might lie would be appreciated. Thanks!

[russg]

Hi all,

I recently rescued my old Atari 800XL from my parents' attic and wanted to give it a whirl. It's just a base unit with an XC12 cassette deck, bust I spent a huge amount of time on it when I was a kid, both playing games and programming. I connected it up and was delighted to find that familiar blue screen looking at me!

 

However, it does not seem to be able to read data from the tape deck. In fact, having the tape deck even attached seems to affect the startup of the computer - with nothing attached to the SIO port, it starts up as normal. With the cassette deck attached however, the little noise before READY appears is different and much faster. I don't know what the purpose of that clicky noise is between the blue screen appearing and READY appearing, but having the tape deck attached affects it where it never used to back when I used it regularly.

 

Anyone have any ideas what might cause this? I'm pretty good technically, but most of my retro experience is repairing Amigas - I don't have any experience with the Atari at all, so any pointers as to where the fault might lie would be appreciated. Thanks!

If you press START at power on, it should beep twice and wait for you to load a binary tape.

You hold OPTION and START if you want to binary load a binary file from tape.

Holding OPTION at startup disables BASIC.

I think, if you boot with the tape on, but without START, you should go to BASIC READY prompt. You can then

CLOAD or LOAD "C" a BASIC program with the tape cued.

If you turn the computer on with the tape attached but turned off, it should ignore the tape and go to BASIC READY.

If you turn the computer on with only OPTION pressed, it should go to the self test screen and ignore the tape.

Edited March 17, 2016 by russg

[Bryan]

Are these helpful? Sounds like the tape deck might not be behaving properly on the SIO bus.

 

 

In this one he holds START/OPTION at power up:

 

[_The Doctor__]

the xc12 cassette door is propably twisted you will need to straighten it... this is common... also the xc-12 is sio powered.. the power supply to the computer may be weak...

 

you can apply gentle heat and pressure to straighten it... some people just take it off..... I suggest straightening it though... be careful how you load cassettes till it is straight or it may damage the head etc...

[Daedalus2097]

Thanks for the replies everyone! Everything appears to be behaving normally other than the startup "pre-READY" noise being much quicker, and the computer ignoring the data from the tape. It still starts the tape deck running and I can still hear the tape data through the audio output of the computer when it starts, but it just sits there with the blank blue screen and cursor until the tape runs out. I also tried using CLOAD to load some programs I wrote myself many moons ago (which can be read fine by WAV2CAS and run in an emulator). No error, the computer just sits there ignoring the tape until I reset it.

 

The startup sound in the first video posted there is what I get when I start it without the tape attached, but with it attached, the clicks are much closer together and READY appears much more quickly. It behaves exactly as in the second video with Start & Option held down as normal, but it never finishes loading. The door on the deck is fine - it all looks mechanically perfect and the audio through the computer appears to be fine.

 

Interesting point about the power supply, I'll check it and see if it's sagging when the computer starts up.

[Rybags]

The data circuit on the tape drive might be sending random garbage over the data line which might cause quick sneeze rather than slow fart sound.

 

You're supposed to hold Start to get the tape to boot though, in which case the attempted disk boot (fart) shouldn't occur until after the tape boot has completed (unless otherwise overridden).

You should here a single load prompt sound then press a normal keyboard key.

 

In normal circumstance the tape shouldn't even play unless you've initiated a load properly.

[Daedalus2097]

Yep, that sounds plausible, and corresponds to what I'm seeing - probably the tape deck so. I might stick a scope on the data line and have a look, though I don't know what it should look like when healthy. Yes, when I try to boot from a tape I get the prompt beep, and it starts the tape when I press Return. The reason I said about the startup sound when booting into BASIC is because it's another symptom that appears to be related.

 

Thanks for the ideas, I'll see if I can find the timing specification and have a look at it.

[Rybags]

Sometimes a tape fails to load because the leader is too long or too short.

 

But if it's a commercially made tape, should work fine from fully rewound position. If something you did yourself, maybe try FF the tape equivalent to about 5 seconds playtime first.

[Daedalus2097]

I've tried commercial and self-made tapes, tried with and without the leader and tried adjusting the position a couple of seconds either side of the start of the recording, no joy. It's actually still in the attic of my parents' house, so next time I'm there I'll dig it out again and check the data coming from the tape deck. It's certainly the suggestion that seems closest to what I'm seeing. Thanks for the help!