We've just updated MediaWiki and its underlying software. If anything doesn't look or work quite right, please mention it to us. --RanAS
REFRESH and DRAMMODE: Difference between revisions
From SnesLab
(added DRAMMODE) |
(see also SRAM) |
||
| (5 intermediate revisions by the same user not shown) | |||
| Line 1: | Line 1: | ||
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). | ||
| Line 11: | Line 11: | ||
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. | 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. | ||
=== See Also === | |||
* [[SRAM]] | |||
=== 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 04:01, 15 July 2024
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.