Different AGNUSes 8372 vs 8375

[Tumbleweed]

What the difference between the different versions of AGNUS?

There's alot of info on the web and across various Amiga forums but seems there is a lot of misinformation out there as well. The Big Book Of Amiga Hardware shows:

Chip Name   Chip Number   Part Number   Used In
Agnus (512K)   8361   252125-01   A1000 (NTSC), A2000A (NTSC)
Agnus (512K)   8361 R3       A1000(NTSC), A2000A(NTSC)
Agnus (512K)   8367   252362-01   A1000 (PAL), A2000A (PAL)
Agnus (512K)   8370   318070-01   A500 (NTSC), A2000 (NTSC)
Agnus (512K)   8371   318071-01   A500 (PAL), A2000 (PAL)
Agnus (1MB)   8372   318069-02   A500 (PAL), A2000 (PAL) Regular Type
Agnus (1MB)   8372A   318069-029   A500 (PAL), A2000 (PAL) (changed after some damage)
Agnus (2MB)   8372AB   318069-03   A3000 (PAL), A3000T (PAL)
Agnus (2MB)   8372B   318069-03   MegAChip (NTSC)
Agnus (2MB)   8375 R0   318069-18   A500+ (PAL), A600 (PAL)
Agnus (1MB)   8375 / 8375 R1   318069-16   A500 (PAL), A2000 (PAL)
Agnus (2MB)   8375 R2   318069-10   A500+ (PAL), A600 (PAL)
Agnus (2MB)   8375   318069-11   A500+(NTSC) and A600(NTSC)
Agnus (1MB)   8375   318069-17   A500 (NTSC), A2000 (NTSC)
Agnus (2MB)   8375   318069-19   A3000 (NTSC), A3000T (NTSC)
Agnus (2MB)   8375   390544-01   A500+ (PAL), A600 (PAL)
Agnus (2MB)   8375   390544-02   A500+ (NTSC), A600 (NTSC)

My question is can I run a 8375 Agnus [Agnus (2MB)   8375   318069-19   A3000 (NTSC), A3000T (NTSC)] in my A3000T which is fitted with a 8372 Agnus [Agnus (2MB)   8372AB   318069-03   A3000 (PAL), A3000T (PAL)]

And if so what are the advantages?

Weed

[Tumbleweed]

Cheers Matt.

Seems BBoH is missing entries. I found that there is a 8375 Agnes (PAL) version for the 3000T:

Agnus (2MB) 8375 318069-18 A3000 (PAL), A3000T (PAL)

Ill do more digging - its the compatibility aspect I'm interested in. As I understand it Agnes has a part to play in DMA - do the later revisions of the chip improve the stability of DMA?

Weed

[Tumbleweed]

@psxphill

Thanks for that doc. Very helpful.

Does anyone know whey there were so many revisions? The jump from 512k to 1MB to 2MB I can understand but why so many versions of the 2MB parts?

Im edging towards leaving the 8372 as is as its not clear what the advantages of the 8375 part are. I did find schematics for an an adapter board to use a 8375 in a A3000D but Ive not found anything yet to show what improvements the 8375 has over the 8372.

Much appreciated.

Weed

[Tumbleweed]

Towards the end Commodore were strapped for cash so maybe they used what the had out of necessity and used whatever parts they had available.

I think Ill stick with what I have - the only reason for considering tinkering was to potentially to improve stability.

I think the small niggle Ive got with he A3000T is it doesnt always boot up from powering on. A reset always resolves it and it boots fine. I think the issue may be caused by the Deneb card I have and potential DMA locking up as I also have a CV64 3D, CV64 and BigRam plus installed. I upgraded Buster to version 11 but I know there are limits to how many bus masters you can have at the same time. The Deneb is configured for DMA. I can force it to use PIO or Zorro II but that will slow down transfer rates accessing a USB pen drive I have plugged in.

Much appreciated.

Weed

[Tumbleweed]

This looks interesting.

https://www.buffee.ca/a-little-side-project/

A new Agnus

Weed