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REFRESH and DRAMMODE: Difference between revisions
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The '''REFRESH''' line comes out of pin 40 of the [[S-CPU]]. It goes into: | The '''REFRESH''' line keeps DRAM from forgetting. It comes out of pin 40 of the [[S-CPU]]. It goes into: | ||
* pin 7 of [[S-WRAM]] | * pin 7 of [[S-WRAM]] | ||
* pin 33 of the [[Cartridge Slot]] | * pin 33 of the [[Cartridge Slot]] | ||
The [[S-CPU]] is paused for 40 master cycles while a REFRESH happens. <sup>[2]</sup> | |||
/'''DRAMMODE''' is the name of pin 49 on the [[S-CPU]], tied directly to ground (low). | /'''DRAMMODE''' is the name of pin 49 on the [[S-CPU]], tied directly to ground (low). | ||
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=== References === | === References === | ||
# https://forums.nesdev.org/viewtopic.php?p=62572#p62572 | |||
# https://problemkaputt.de/fullsnes.htm#snestimingoscillators | |||
[[Category:SNES Hardware]] | [[Category:SNES Hardware]] | ||
[[Category:Traces]] | [[Category:Traces]] | ||
Latest revision as of 01:21, 15 July 2023
The REFRESH line keeps DRAM from forgetting. It comes out of pin 40 of the S-CPU. It goes into:
- pin 7 of S-WRAM
- pin 33 of the Cartridge Slot
The S-CPU is paused for 40 master cycles while a REFRESH happens. [2]
/DRAMMODE is the name of pin 49 on the S-CPU, tied directly to ground (low).
In 2010, 6502freak theorized that setting this pin high disables the refresh cycle logic and frees up CPU time.
In 2013, nocash tested Donkey Kong Country with /DRAMMODE high. The game ran normally, so he hypothesized that when setting REFRESH low the game would still work too.