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Author Topic: Fat Agnus 8372A vs 8375?  (Read 10069 times)

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Offline AmigaPixelTopic starter

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Fat Agnus 8372A vs 8375?
« on: March 09, 2008, 11:34:32 AM »

 Does anyone know the diffrence between the Fat Agnus 8372A and 8375? I have the 8372A installed but had an extra 8375 I sold on Ebay.
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Offline alexh

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Re: Fat Agnus 8372A vs 8375?
« Reply #1 on: March 09, 2008, 04:07:51 PM »
Which versions, there are close to 10 of slightly different 8375 chips.

318069-10, 318069-11, 318069-16, 318069-17, 318069-18, 318069-19, 390544-01, 390544-02

Not all 8375 chips are pin compatible with all Amiga's

What's it for?

Only the 1Mbyte 8375 chips (318069-16 / 318069-17) are drop in replacements for the 8372A.

A 1Mbyte 8375 is effectively identical to a 1Mbyte 8372A.

http://groups.google.co.uk/group/comp.sys.amiga.hardware/msg/259d7e187bd3b044
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Offline AmigaPixelTopic starter

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Re: Fat Agnus 8372A vs 8375?
« Reply #2 on: March 10, 2008, 01:38:27 PM »

 Oh! good question, I don't know since I sold it.Is the   8372A ECS or OCS? I remember seeing one of these chips with an HP logo stamped on it. I thought that was pretty cool, they must of been licsense to make a few. I am pretty sure it was the Fat Agnus chip.
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Offline rkauer

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Re: Fat Agnus 8372A vs 8375?
« Reply #3 on: March 10, 2008, 01:45:17 PM »
 The ECS 8375 Fat Agnus is not pin-compatible with A500 or A2000.

 If you want to put an ECS Agnus in your OCS Amiga, you need to re-route some wires.
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Offline alexh

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Re: Fat Agnus 8372A vs 8375?
« Reply #4 on: March 10, 2008, 01:45:24 PM »
Quote

AmigaPixel wrote:
Is the 8372A ECS or OCS?

ECS.

Quote

AmigaPixel wrote:
I remember seeing one of these chips with an HP logo stamped on it. I thought that was pretty cool, they must of been licsense to make a few. I am pretty sure it was the Fat Agnus chip.

AFAIK HP did not make any Agnus chips. They were all made at CSG (Commodore Semiconductor Group) formally known as MOS.

The A1200 AGA Lisa was fabbed at HP

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Offline alexh

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Re: Fat Agnus 8372A vs 8375?
« Reply #5 on: March 10, 2008, 01:48:55 PM »
Quote

rkauer wrote:
 The ECS 8375 Fat Agnus is not pin-compatible with A500 or A2000.

That statement is not entirely correct. The 8375 1Mbyte Agnus chips are pin compatible with the later A500 motherboards. i.e. An A500 (non plus) with 1Mbyte chip ram and an 8372A Agnus.

I dunno about A2000, but I would imagine the same is true.

Quite why you would want to do such a thing I dont know.
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Offline bloodline

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Re: Fat Agnus 8372A vs 8375?
« Reply #6 on: March 10, 2008, 01:54:20 PM »
Quote

alexh wrote:
Quote

AmigaPixel wrote:
Is the 8372A ECS or OCS?

ECS.

Quote

AmigaPixel wrote:
I remember seeing one of these chips with an HP logo stamped on it. I thought that was pretty cool, they must of been licsense to make a few. I am pretty sure it was the Fat Agnus chip.

AFAIK HP did not make any Agnus chips. They were all made at CSG (Commodore Semiconductor Group) formally known as MOS.

The A1200 AGA Lisa was fabbed at HP




I seem to remember the reason for HP was due to Lisa being a hybrid chip, which required technology not available at MOS...

I can't believe making all those different variants of chips was cost effective... They should have fixed on one over specified and used it in all devices... :-)
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Offline rkauer

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Re: Fat Agnus 8372A vs 8375?
« Reply #7 on: March 10, 2008, 03:07:30 PM »
Quote

alexh wrote:
Quote

rkauer wrote:
 The ECS 8375 Fat Agnus is not pin-compatible with A500 or A2000.

That statement is not entirely correct. The 8375 1Mbyte Agnus chips are pin compatible with the later A500 motherboards. i.e. An A500 (non plus) with 1Mbyte chip ram and an 8372A Agnus.

I dunno about A2000, but I would imagine the same is true.

Quite why you would want to do such a thing I dont know.


 To use 2Mb on board?

 IIRC, the 8372a just accept 1Mb, not 2Mb like ECS 8375. BTW: AFAIR, 1Mb Agnuses are OCS, not ECS.
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Offline Zac67

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Re: Fat Agnus 8372A vs 8375?
« Reply #8 on: March 10, 2008, 03:23:40 PM »
I assume the 8375 was designed to cover all three variants with one single chip. However, to make it pin-compatible to its predecessors, its models differ in bonding.

Strangely 8372ABs have been reported to be made after the 8375s, but that was probably due to some manufacturing problems (which CSG had quite a lot of).

And yes, 1 MB 'Fatter' Agnuses are ECS, I'm running an 8372A in my first A500 with a Hires Denise.
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Offline alexh

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Re: Fat Agnus 8372A vs 8375?
« Reply #9 on: March 10, 2008, 03:43:29 PM »
Quote

rkauer wrote:
To use 2Mb on board?

No to use 1Mbyte.

Quote

rkauer wrote:
IIRC, the 8372a just accept 1Mb, not 2Mb like ECS 8375.

Two of the 8 variants of 8375 chips are 1Mb only.

Quote

rkauer wrote:
BTW: AFAIR, 1Mb Agnuses are OCS, not ECS.

I don't know for sure. I do not know what the distinction is .

I only learned last month that there is possibly a chipset BEFORE OCS called ICS! It was in the early Amiga's. There is debate as to whether it should have it's own name, but it definitely differs in capability to OCS. Denise has no EHB and Agnus has slightly different capabilities too.
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Offline SamuraiCrow

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Re: Fat Agnus 8372A vs 8375?
« Reply #10 on: March 10, 2008, 03:52:05 PM »
@rkauer

OCS could accept a maximum of 512K chip RAM.  The 1 meg fat Agnus could be used with an OCS Denise graphics display but the Super-Denise upgrade, when used with the older 1 meg Agnus chips, would make it full ECS.
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Offline AmigaPixelTopic starter

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Re: Fat Agnus 8372A vs 8375?
« Reply #11 on: March 13, 2008, 12:24:15 AM »

 I originally purchased the 8375 from SoftHut to replace the 8372A because I thought it might be the cause of the my A2000 locking up. But i turned out to be the 8mb simm on the 030 that had gone bad. I swapped for 16mb I pulled out of an old Sony Vio. The problem was solved.

The 8375 still showed as 1 meg. Could it be wired to be a 2 meg configuration? In other words is it like the Fatter Agnus found in the A3000 but backwards compatible as an  1meg when no modification is done?

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Offline AmigaPixelTopic starter

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Re: Fat Agnus 8372A vs 8375?
« Reply #12 on: March 13, 2008, 12:31:16 AM »
 The funny thing about the lock up issue, was it only occured after the first 5 minutes. And only if I switched to Workbench. If I stayed in the program like ImageFX I could keep going as long as I wanted.
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Offline rkauer

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Re: Fat Agnus 8372A vs 8375?
« Reply #13 on: March 13, 2008, 12:41:45 AM »
 A3000's Fatter Agnus is not pin-compatible with A500/+/2000!

 I don't remember if there was a 2Mb version for A500/2000 pin compatible. But you dare, take a look at the A3000's pinout and the A500/2000 schematics to know how to re-route the traces needed.

 BTW: IIRC, the A600/3000 Agnus pinouts is very hard to find... Someone have it? If so, send to meh, plizzzzzzzz?
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Offline alexh

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Re: Fat Agnus 8372A vs 8375?
« Reply #14 on: March 13, 2008, 12:46:04 AM »
Quote

AmigaPixel wrote:
The 8375 still showed as 1 meg. Could it be wired to be a 2 meg configuration?

No.
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