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Chris.LDN

Posted Sat Jul 17, 2021 4:54 am

After years of searching/waiting/saving I'm finally (once again) the proud owner of an Amiga 1000 after my parents gave away our family A1000 many years ago.

It's a beauty with almost no signs of wear or tear including the original box! :D

The only issue I have hit is this:

Your browser does not support the video tag.
  • Double-click does not work, tried multiple mice
  • Clock "freaks out"
I ran Amiga Test Kit and found this:

Image


So it looks like I have a bad CIA chip. I read the it's possible to swap the chip around so I did:

Image

Double click now works! :D

Clock now works! :D

However Amiga Test Kit still reports the same CIA errors :(

So I guess I need to replace the CIA chips. Before I do, I'm hoping you guys can answer:

1) Should I replace both CIA chips or just one of them?
2) The current CIA chips are both MOS 8520R2. Are these the same as MOS 8520A-1?
3) Will this do the trick?

User avatar
iljitsch
Website

Posted Sat Jul 17, 2021 5:27 am

I have no answer to the question, but...

It sure sounds like you were almost ready to sing the chicken lips blues! (money quote: 2:40)

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intric8
Seattle, WA, USA
Website

Posted Sat Jul 17, 2021 9:03 am

I had a CIA chip go out on me, too. You're kinda lucky - my machine wouldn't even boot! It was a mess.

I only changed the one chip, though. And I don't know if an A500 CIA (which I do see on Ebay) will work in an A1000. Some very interesting info about them here. Sounds like the Amiga's CIA was very similar to one also found in the 1581 disk drive!
The 8520 revision of the CIA, as used in the Amiga and the Commodore 1581 disk drive, modified the time-of-day clock to be a 24-bit binary counter, replacing the BCD format of the 6526. Other behavior was similar, however.
I have a feeling the CIA of a 500 should work, but I don't know 100% for sure. Hopefully one of the hardware gurus here can give you a definitive answer.

User avatar
intric8
Seattle, WA, USA
Website

Posted Sat Jul 17, 2021 9:11 am

UPDATE:

I found this.
The only compatible [A500] chips are Denise (Daphne on early boards), Paula (Portia on early boards), and the CIA chips.
If that's true you should be good to go. The whole thread is worth a read as the CIA's sound to be finicky as hell.

User avatar
Chris.LDN

Posted Sat Jul 17, 2021 2:22 pm

Excellent, thanks for you help! I've found a pair of 8520A-1's on Ebay for £25 and it's local to me so I should have them in a few days.

https://www.retropassion.co.uk/ is about an 1.5hr drive from me so I'm hoping within the next a few weeks I'll drop my A1000 (and some other bits and pieces) there for Steve to recap and clean. He supplied me an A600 and recapped my A1200 a while back so I have complete trust my A1000 will be in good hands.

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A10001986
1986
Website

Posted Sun Jul 18, 2021 6:36 am

Just any 8520 will work, as long as it's a DIP version. The PLCC ones won't fit, naturally.

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retrorewind.ca

Posted Mon Jul 19, 2021 7:21 pm

intric8 wrote:
Sat Jul 17, 2021 9:11 am
UPDATE:

I found this.
The only compatible [A500] chips are Denise (Daphne on early boards), Paula (Portia on early boards), and the CIA chips.
If that's true you should be good to go. The whole thread is worth a read as the CIA's sound to be finicky as hell.
You can totally use the CIAs from a 500 in a 1000.

User avatar
McTrinsic

Posted Tue Jul 20, 2021 6:25 am

Didn’t the C128 CIAs work also? Or was it the other way round. Like, being able to put Amiga CIAs in a C128.

User avatar
iljitsch
Website

Posted Tue Jul 20, 2021 10:32 am

Hm I believe the 8520s have a different time-of-day clock and the Amiga runs at 7 MHz, the C128 only 2 MHz...

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nadoom

Posted Wed Jul 21, 2021 3:59 am

The CIA chips are as old as the hills and very similar to the ones used in the C64 so I expect they will work across all OCS/ESC amiga models. Glad u were able to diagnose the problem and can now fix it easily :)





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