Atari 800XL blue screen and cursor. No READY.

[llopis]

I have an Atari 800XL in good apparent condition. When I turn it on, I get the normal blue screen with the dark border. I even get as far as getting a block cursor, but I never get the normal READY message.

 

Any idea what might be wrong? Without knowing much about it, I would think the BASIC ROM, but someone will probably have a better idea.

 

A couple pre-emptive questions:

- If it's the ROM, I saw it's a 32-pin IC, so it's not a straightforward substitution with a 27C128. Any idea what kind of EPROM I could use to replace it?

- Is there a repository of preserved system ROMs for Atari 8-bit computers somewhere?

 

Thanks!

 

[ebiguy]

try with a game cartridge to check if everything is working (basic is disabled).

If the game does not work then BASIC is not the problem.

[DavidMil]

Have you tried booting into test mode (hold down the Option key while turning on the computer)? And also turn on the PC will holding down the Start key to see if you get a beep (tape drives is

loading sound).

 

David

[tane]

I have an Atari 800XL in good apparent condition. When I turn it on, I get the normal blue screen with the dark border. I even get as far as getting a block cursor, but I never get the normal READY message.

 

Any idea what might be wrong? Without knowing much about it, I would think the BASIC ROM, but someone will probably have a better idea.

 

A couple pre-emptive questions:

- If it's the ROM, I saw it's a 32-pin IC, so it's not a straightforward substitution with a 27C128. Any idea what kind of EPROM I could use to replace it?

- Is there a repository of preserved system ROMs for Atari 8-bit computers somewhere?

 

Thanks!

 

 

It's the Pokey chip. If you remove it and then turn the Atari on, it's the same behavior.

[_The Doctor__]

who knows maybe you acquired a modified unit.. have you looked at the main board yet?

looks like some suggestions are already posted.

Edited February 1, 2019 by _The Doctor__

[+Nezgar]

BASIC ROM is 24 pins. To replace with an EPROM, requres a 2764->2364 adapter.

OS ROM is 28 pins. 27C128 EPROM is a drop-in replacement.

POKEY is 40 pins.

 

I'd start with re-seating those 3 at a minimum, hopefully they're socketed.

[llopis]

try with a game cartridge to check if everything is working (basic is disabled).

If the game does not work then BASIC is not the problem.

Doh! I can't believe I didn't try that :-) The cartridge loads fine.

 

Have you tried booting into test mode (hold down the Option key while turning on the computer)? And also turn on the PC will holding down the Start key to see if you get a beep (tape drives is

loading sound).

 

David

I tried that, but it didn't do anything.

[llopis]

BASIC ROM is 24 pins. To replace with an EPROM, requres a 2764->2364 adapter.

OS ROM is 28 pins. 27C128 EPROM is a drop-in replacement.

POKEY is 40 pins.

 

I'd start with re-seating those 3 at a minimum, hopefully they're socketed.

That's right! I remember counting and the BASIC ROM not being 28 pins. It's 24.

 

Of those, only the POKEY chip is socketed. I took it out and put it back in again, but there was no difference.

 

Could still be the POKEY even though cartridges load fine?

[llopis]

I realized that the 800XL shares a lot of chips with the 600XL, and I have several of those around. So I first changed the BASIC ROM and... nothing. Then I changed the POKEY chip and... bingo! That was it.

 

Also, for completeness sake, I tried turning on the computer with a working POKEY and without a BASIC ROM, and it went straight to the self test. Good to know for the future.

 

Now off to see of POKEY chips are easily available to purchase. I have a bad feeling about any chips with proper names :-b

[+DrVenkman]

I realized that the 800XL shares a lot of chips with the 600XL, and I have several of those around. So I first changed the BASIC ROM and... nothing. Then I changed the POKEY chip and... bingo! That was it.

 

Also, for completeness sake, I tried turning on the computer with a working POKEY and without a BASIC ROM, and it went straight to the self test. Good to know for the future.

 

Now off to see of POKEY chips are easily available to purchase. I have a bad feeling about any chips with proper names :-b

Best Electronics has NOS (New, Old Stock) POKEYs though they are relatively pricey at $20 each, limit 1.

[+Nezgar]

Also, for completeness sake, I tried turning on the computer with a working POKEY and without a BASIC ROM, and it went straight to the self test. Good to know for the future.

 

Yep, but if you watch the memory test, you'll see it's still missing the 8KB of RAM reserved for the BASIC ROM even when the chip is not physically present, unless you held OPTION on powerup.

[llopis]

Best Electronics has NOS (New, Old Stock) POKEYs though they are relatively pricey at $20 each, limit 1.

I reached out to them a couple of weeks ago about getting a POKEY but they never replied. Are they still in business? (Yes, I read their page about having the right incantation in the subject line).

 

Any other sources for a POKEY chip? (especially in Europe).