There were several versions of Agnus created over the years by Commodore. Based on a previous discussion around here about the Agnus chip, I wanted to see if I had a proper replacement (going from PAL to NTSC). But since I personally didn’t know which chips were which I needed to do a little bit of homework first.
Here’s what was created back in the day for reference:
- OCS Agnus which can address up to 512 kB of Chip RAM (PLCC versions add 512 kB of pseudo-fast RAM)
- 8361 (DIP) - Amiga 1000 (NTSC); Amiga 2000 model A (NTSC)
- 8367 (DIP) - Amiga 1000 (PAL); Amiga 2000 model A (PAL)
- 8370 (PLCC) - Amiga 500 to Rev 5.x (NTSC); Amiga 2000 model B to Rev 4.5 (NTSC)
- 8371 (PLCC) - Amiga 500 to Rev 5.x (PAL); Amiga 2000 model B to Rev 4.5 (PAL)
- ECS Agnus which can address up to 1 MB of Chip RAM
- 8372 - no data*
- 8372A - Amiga 500 from Rev 6 (NTSC/PAL); Amiga 2000 model B from Rev 6.0 to Rev 6.3 (NTSC/PAL); Commodore CDTV
- 8375 (318069-16 only) (PAL) - Amiga 500 from Rev 6 (PAL); Amiga 2000 model B from Rev 6.4 (PAL)
- 8375 (318069-17 only) (NTSC) - Amiga 500 from Rev 6 (NTSC); Amiga 2000 model B from Rev 6.4 (NTSC)
- ECS Agnus which can address up to 2 MB of Chip RAM
- 8372AB - Amiga 3000 from Rev 6.1 to Rev 8.9 (NTSC/PAL)
- 8372B - Amiga 3000 Rev 9 (NTSC/PAL)
- 8375 (PAL) - Amiga 500 Plus; Amiga 600 (PAL)
- 8375 (NTSC) - Amiga 600 (NTSC)
Well, boo.Agnus was replaced by Alice in the Amiga 4000 and Amiga 1200 when the AGA chipset was introduced in 1992.
Agnus Slang
Poor Agnus got called a lot of names, and most not particularly nice. It seems to depend on which continent you’re from, but I’ve heard various names thrown around for the various levels of Agnus’. I think it goes something like this:
Agnus = 512KB
Fat Agnus, Obese Agnus = 1MB
Super Fat Agnus, Super Obese Agnus = 2MB
And, I think, if you're running "Super Fat Agnus" on Phoenix/500/2000 you have to use what's called the MegaChip, which is a small board that sits into the slot that Agnus used to reside in, and your 2MB Agnus fits into the board. With the A3000 you were good-to-go.
My own personal stock of extra Agnus chips: Here’s what I know:
- My daily-driver A2000 is running the ECS 8375 (PAL), which has 2MB of Chip RAM.
- I have 3 spare loose chips.
- Two: 8372A (318069-02) - this is an ECS 500/2000 1MB chip. I don’t know if mine are PAL or NTSC, but assume they are NTSC.
- 8372B (318069-03) - this is a 2MB Agnus. Again, I don’t know if it is NTSC or PAL. The one in my daily is PAL. I have a sneaking suspicion this one is NTSC, as I have the original box and it was marked NTSC. That being said, I’ve never had any issues with it and my 2000 looks, smells and acts like an NTSC machine through and through.
In regards to our previous discussion about maybe making my Phoenix 100% NTSC, I think if I put one of my loose 8372A’s in the Phoenix in theory that should do the trick (if it’s an NTSC chip, which they all should be).
And I think my loose 8372B is in fact an NTSC chip. I wonder if i should put it in my daily driver (which doesn’t really have any issues except the viewable 4:3 is slightly off-center) or leave it be? What's really interesting about that is that in the Phoenix's user manual, it claims to have full support for this chip built in... The Agnus for the A3000. Really? With no mods? Seems hard to believe.
To more tests!