Closed Fat Agnus (Any version)

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rcade

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Looking for fat Agnus, 8372A preferable... I have an 8375 that is the -18 VBB version, which won't work with 1MB chip in A500 Rev5, and I have an 8370 PAL Agnus already.
 
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Hmm...don't know what You want to do with them,
just want to point out - chips You mentioned have different pinout, so it's impossible to use them on same board without adapter..
 
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I thought any of those would run in an A500 and the only pinout difference was 8372AB (for the A3000)?

Ah, I checked - you are right of course. So I guess some models of 8375 are not compatible? I have an 8375 in there now that will not get past the second gray screen. Maybe that is the whole problem...
 
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Nope!
You can use 8375 Agnus in A500 (not Plus),
However You need a special adapter (Megachip)
8370 will not fit, because You will get problems with refreshing due different RAM chip (rev 3 & 5 have 16 chips)
 
I currently have a rev5 board, and an 8370 works fine in it. I also have an 8375 that does not, but I need to check the version as I may have one with a different pinout.
 
OK, mine is an 8375 318069-19, which looks like an 8372B variant. I guess that's why it won't boot in my A500.

So, I do still need an Agnus, or an adapter... Even if so, will this A3000 variant work in a Megachip?
 
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It turns out that the 8375 318069-19 "VBB" seems to work just fine in my Rev5 A500. Crazy, eh? The list I found says this is the A3000 variant, when it clearly is not, and no adapter.

The ultimate problem turned out to be some traces I broke replacing all the RAM (what a pain, socketed 16 chips). It seems to run fine now...

 
Upon further work on this machine, it's still not right.

I have modified the board to allow 1MB chip RAM, but it would not work with the 318069-19 "VBB" Agnus. Green screen. However, it still works fine set up only as 512k chip RAM with no problem. I guess it is not pin compatible with the 8327A?

So, still looking for 8372a...
 
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As you live in the States, I gather the Rev 5 board is NTSC, the following numbers are probably what you are after
( If you are not sure if it is NTSC or PAL, have a look at the Crystal (oscillator) near the Agnus, values 28.6363 = NTSC, 28.37516 = PAL)
(If you are not sure what the crystal is, google is your friend:))

8375 318069-17 (1Meg) Agnus NTSC
8372A 318069-02 (1Meg) Agnus NTSC / PAL

I have a 318069-02 in an NTSC A2000 MB.
Unfortunately I am still using it ATM, but I am thinking of converting this board to PAL and installing a megachip
If it becomes available and you are still looking will send you a PM
cheers,
Dan
 
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Individual Computers sells the chip you're looking for. I ordered one a few weeks back.
 
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