1 reply to this topic

[gdement]

I recently realized that there are 2 revisions of the NTSC Maria chip in production 7800's:

C024674 Maria-B
C025349 Maria-C

I found a B in my 1987 console and a C in my 1988 console. Looking them up online turned up the "Master Chip Listing" that Curt Vendel posted.
There's also a PAL Maria (C025718), but only 1 listed so I assume it's equivalent to the C revision.


What are the differences between revision B and C? There must be something different about them. I'm curious if these differences are known and if they might have any obscure effect on programming.

In the GCC 2004 reunion audio, one of the chip designers made a reference to how many times he had to revise the Maria, but didn't elaborate on what the issues were except for the first prototype.

[GroovyBee]

gdement, on Wed May 20, 2009 5:21 AM, said:

What are the differences between revision B and C? There must be something different about them. I'm curious if these differences are known and if they might have any obscure effect on programming.

I doubt theres anything different in software interface terms. There isn't a "revision register" to detect what rev the silicon is at. If the revision register existed, its contents could be used to make the software behave differently (based on the MARIA detected). Having said that, in the past I've used other "features" of a chip to detect its revision. Its not always clear cut .