Help to identify this A500 mood.

[desantii]

I thought most 8272s chips were the 8372A variant that address 1mb chip ram. Only the 8272 A/B or 8372B can address 2mb (both of these found in A3000s)

I had always thought 8371s were 512kb... we'll you learn something new everyday


1mb

I gots to reading..... .....  a lot =)


an OCS chip set is just that, it comprises of DENISE, and 8370 Agnus.

an ECS chip set seen on the A500 is a Super Denise and an 8375 Agnus, this is also an A600 as well.

Now this will bake your noodle a bit, what makes the chip set OCS or ECS is in fact the Denise.  If you have a Super Denise installed you essentially have an Enhanced Chipset, as you gain extra screen modes.

Agnus is just an (Address Generator Unit) - depending on what you have 8370, 8371, 72, 74 will determine the address it can generate, it also handles some aspects of video in regards to PAL / NTSC.

the 8370 can address 512KB of CHIP
the 8371 can address 1MB of CHIP
the 8372 can address 2MB of CHIP*
the 8375 can address 2MB of CHIP*

*I should mention that there are some revisions of 8372 and 8375 that can only address 1MB of CHIP - most notably a particular revision in the early rev5.3 A2000's

Sadly I don't think Commodore had any idea when it came to name convention and there are some crazy revisions within each iteration - its quite difficult to get a right answer as well as very easy to be complete confused.

Alexh, I believe a member here, he probably knows more about Agnii than anyone outside the designers at commodore to be honest