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General Category => Technical support - Hardware related => Topic started by: Overkill on 17:51, 21 June 24

Title: Messed-up spites, is it that the Plus is just fussy about the RAM?
Post by: Overkill on 17:51, 21 June 24
Hello all, I have a 464 Plus that was dead (Someone had already had a repair attemp  :picard:).

I should point out, that this was a 6128 Plus board, but the 6128 parts have been removed.

I found 4 bad traces and have soldered in 4 bodge wires, now I have a picture and it will run the diagostic ROM without error, apart from the corrupted sprites.
You can also see that Burning Rubber has messed-up graphics and sometimes crashes.

The board has sockets for the RAM, and I have loads of NEC 41464-10 and a few NEC 41464-12 but some seem better than others.  I do have 1 original working KMS RAM, and it seems to crash less with that one installed.

I could pinch another KMS from another board, but I thought I'd get all your thoughts first :)
Title: Re: Messed-up spites, is it that the Plus is just fussy about the RAM?
Post by: abalore on 18:26, 21 June 24
If it only fails in Plus features, but not in CPC games, I would bet the problem is a faulty ASIC.
Title: Re: Messed-up spites, is it that the Plus is just fussy about the RAM?
Post by: Overkill on 19:17, 21 June 24
Quote from: abalore on 18:26, 21 June 24If it only fails in Plus features, but not in CPC games, I would bet the problem is a faulty ASIC.
It's not 100% stable just on the BASIC screen.
Title: Re: Messed-up spites, is it that the Plus is just fussy about the RAM?
Post by: andycadley on 23:12, 21 June 24
The Plus sprites are stored in registers inside the ASIC, so it's either a failing ASIC or a fault on the bus which is causing corruption when the Z80 is reading/writing data. 
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