8375 are newer versions of what? What Amigas work with them?

Hello,
I have a pair of FAT Agnus 8375 here.

Which Amigas do they work in? Are they an updated version of the 8372A or B ? How much chip RAM to they support?

Thank you all!

[Lokki]

What Commodore part number are they?
Most likely 2Meg and different pinout.
A500+, A600, etc - dependant on part number.

Lokki wrote:
What Commodore part number are they?
Most likely 2Meg and different pinout.
A500+, A600, etc - dependant on part number.

They are part no. 318069-17 and they have the same PLCC package as all other fat Agnus I have ever seen; 8370, 8371, and both 8372A and B.

[Lokki]

They appear to be listed on BBoAH as a 1 meg A500/A2000 Agnus... it would be interesting to know for sure if the pinout is the same as the 8372s.

[James]

If they're the 'Fatter Agnus' variety, they were around quit a lot a few years back between the A3000 and A500+. OCS owners would hack away at their 500s for 1mb of CHIP ram. It also enabled NTSC machines to boot in PAL.

They are getting increasingly rare. Its the reason why got myself a 600 instead of a 500, I didn't want to have to look for one of these.

[alexh]

These are a 1-Meg varient of the SuperFAT (2-Meg) Agnus which was made for the A500+/A600 and has a packaging / bondout to make them compatible with ECS machines.

They are directly usable in 1-Meg Amiga's. A500/A2000/CDTV computers.

To make them usable in earlier 512k Amiga's you have to do some work, add a capacitor, cut a track, change a jumper.

http://www.l8r.net/technical/t-agnus-installation.shtml

@James

You've got the date wrong for this chip. They are some of the last chips made ever by commodore. The earliest date code I've seen for a -17 chip is Week 25, 1992.

-17 is NTSC

[alexh]

eslapion wrote:
they have the same PLCC package as all other fat Agnus I have ever seen; 8370, 8371, and both 8372A and B.

Unfortunately most Agnus chips have exactly the same PLCC packaging but they have a widely different electrical pinout.

[voxel]

Hi :-)

Look at it more closely, if you see 8375 VBB on it it's a 2Meg Agnus :-)

without VBB it's 1Meg sort of it :-)

[alexh]

VBB is a process code. Not sure exactly what it means but it is something to do with the factory / packaging / ESD.

It has nothing to do with functionality what so ever!

Lots of oher Amiga chips (Denise, Paula, Budgie etc.) made at the same time also have VBB on them.

I've got 2-Mbyte Agnus chips without VBB printed on them and I have 1-Mbyte ones with VBB printed on.

[satiropan]

since you seem very expert on all the Fat Agnus evolution, I have one question for you:
I was planning to do this 2MB Agnus chipram modification to my A2000 rev6.2:

http://mylinuxisp.com/~jdbaker/oldsite/documents/2MBAgnushack_v1.4.txt

For this I bought a 8375 390544-01 4291 20 chip from ebay, don't know which machine it came from.
But now I have the doubt: is my 2MB Agnus pin compatible with the one requested in the modification, which should be a 8372B or 8375B Agnus part number 318069-03?
And... where can I find a trustful pinout description for all these chips?
BTW, I invite you to visit my site, www.oldfab.tk and check the mods I did.
Ciao
Satiropan

[amesie2]

The 8375 is used in the DKB Megachip to give 2MB of ram according to BBOH.

[amesie2]

The 8375 is used in the DKB Megachip to give 2MB of ram according to BBOH.

[alexh]

satiropan wrote:
I bought a 8375 390544-01 is it pin compatible with the 8372B or 8375B Agnus part number 318069-03?

I am not sure. It's a case of suck it and see. If your A2000 catches fire, dont blame me ;-)

And... where can I find a trustful pinout description for all these chips?

Nowhere. I've not been able to find any real information despite many pleas here and usenet.

[Ilwrath]

Unfortunately most Agnus chips have exactly the same PLCC packaging but they have a widely different electrical pinout.

Really??  Which ones are these, so we can look out for them?  It would be a shame to accidentally fry one.  All I've encountered have been pin compatible, but admittedly, I haven't gone looking for trouble, either.  ;-)

To make them usable in earlier 512k Amiga's you have to do some work, add a capacitor, cut a track, change a jumper.

Actually, they are USABLE as a direct drop-in replacement in an A500.  No mods needed.  And they provide boot-time PAL/NTSC switching without mods (rev 5 and earlier A500s won't do that otherwise).  If you want to enable the extra 512k CHIP RAM, then yes, thats how to do it.  

[alexh]

amesie2 wrote:
The 8375 is used in the DKB Megachip to give 2MB of ram according to BBOH.

The Agnus page of BBoH is a little screwed up. It is not a 100% accurate source of information.

But yes you can find the 8372B 318069-03 and 8375 390544-01 on the DKB MegaChip. However it is not known if they changed the PCB to use one or the other.