Chip differences...

[+kheller2]

I'm running through my stockpile of 8bit chips and came accross some differences that lead to questions I hope my fellow 8bitters can answer.

 

What is the difference between Antic (CO12296D) and Antic XL/XE (CO21697)? I have a blurb of text here that states the 12296 is a direct replacement for 21697 except in the case of the 130XE -- so this leads me to believe 21697 has some additional memory related circuits.

 

I also have a GITA (CO14805-03) stamped "5200 Only". Most of my other GTIAs are 14805-01. So what is so special about -03 5200 Only?

 

Thanks,

 

Karl

[+warerat]

I'm running through my stockpile of 8bit chips and came accross some differences that lead to questions I hope my fellow 8bitters can answer.

 

What is the difference between Antic (CO12296D) and Antic XL/XE (CO21697)? I have a blurb of text here that states the 12296 is a direct replacement for 21697 except in the case of the 130XE -- so this leads me to believe 21697 has some additional memory related circuits.

 

I also have a GITA (CO14805-03) stamped "5200 Only". Most of my other GTIAs are 14805-01. So what is so special about -03 5200 Only?

 

Thanks,

 

Karl

 

I know for sure the CO21697 (ANTIC "E") generates an additional bit in the address counter during a refresh cycle-- refreshes 256 rows instead of 128. So, the internal refresh counter on the CO12296 is 7-bits, and 8-bits on the CO21697. You can use a CO21697 in place of a CO12296 (I'm running an 800 with one). Not always the same way around unless you generate the refresh for larger DRAMs separately or use modern DRAMs with internal refresh counters, which in that case, you don't care about row address during RAS (which is what goes on the address bus when ANTIC's -REF is asserted).

 

Wouldn't think there would be any functional differences in the GTIA between the 5200 and the regular machines, but then again as I'm not as familiar with the GTIA timings.

[re-atari]

I know for sure the CO21697 (ANTIC "E") generates an additional bit in the address counter during a refresh cycle-- refreshes 256 rows instead of 128. So, the internal refresh counter on the CO12296 is 7-bits, and 8-bits on the CO21697. You can use a CO21697 in place of a CO12296 (I'm running an 800 with one). Not always the same way around unless you generate the refresh for larger DRAMs separately or use modern DRAMs with internal refresh counters, which in that case, you don't care about row address during RAS (which is what goes on the address bus when ANTIC's -REF is asserted).

Correct. Antic CO14887 provides a 7-bits refresh, CO21698 a 8-bits refresh (both nrs. referring to PAL version). When upgrading memory to 256K on a system with an Antic CO14887 you'd have to add extra some circuitry to create the missing refresh bit.

 

re-atari