Talk:MMC3 pinout: Difference between revisions
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(→PRG RAM /CE and PRG RAM +CE: fixed a mistake on the pinout) |
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How PRG RAM +CE works? Is it just inverted PRG RAM /CE? Or it's controlled via the $A001 register while PRG RAM /CE is low when $6000-$7FFF addressed? [[User:Cluster|Cluster]] ([[User talk:Cluster|talk]]) 19:03, 8 August 2021 (UTC) | How PRG RAM +CE works? Is it just inverted PRG RAM /CE? Or it's controlled via the $A001 register while PRG RAM /CE is low when $6000-$7FFF addressed? [[User:Cluster|Cluster]] ([[User talk:Cluster|talk]]) 19:03, 8 August 2021 (UTC) | ||
:I am pretty sure (but not confirmed) +CE is being controlled by $A001 bits 6 and 7, and /CE is being controlled by the CPU address bus range $6000-7FFF. (/ROMSEL, A14, A13 = 1,1,1) [[User:Ben Boldt|Ben Boldt]] ([[User talk:Ben Boldt|talk]]) 19:08, 8 August 2021 (UTC) | :I am pretty sure (but not confirmed) +CE is being controlled by $A001 bits 6 and 7, and /CE is being controlled by the CPU address bus range $6000-7FFF. (/ROMSEL, A14, A13 = 1,1,1) [[User:Ben Boldt|Ben Boldt]] ([[User talk:Ben Boldt|talk]]) 19:08, 8 August 2021 (UTC) | ||
::Furrtek's reverse-engineered schematic from the die shots of the ULA [https://github.com/furrtek/VGChips/tree/master/Nintendo/MMC3C] show that pin is just /RD... so I grabbed a continuity tester and verified that /CE on my NES-TSROM-08 cart here is grounded, and that pin 30 is /OE. | |||
Revision as of 00:43, 9 August 2021
Pinout with chip rotated 45°
No offense but the pinout with the chip rotated 45° by Lidnariq in july 2012 looks awful in my personal opinion. (How could it go unnoticed by me for 6 years ?!) Bregalad (talk) 05:55, 5 October 2018 (MDT)
PRG RAM /CE and PRG RAM +CE
How PRG RAM +CE works? Is it just inverted PRG RAM /CE? Or it's controlled via the $A001 register while PRG RAM /CE is low when $6000-$7FFF addressed? Cluster (talk) 19:03, 8 August 2021 (UTC)
- I am pretty sure (but not confirmed) +CE is being controlled by $A001 bits 6 and 7, and /CE is being controlled by the CPU address bus range $6000-7FFF. (/ROMSEL, A14, A13 = 1,1,1) Ben Boldt (talk) 19:08, 8 August 2021 (UTC)
- Furrtek's reverse-engineered schematic from the die shots of the ULA [1] show that pin is just /RD... so I grabbed a continuity tester and verified that /CE on my NES-TSROM-08 cart here is grounded, and that pin 30 is /OE.
