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FastROM: Difference between revisions
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'''FastROM''' is 3.58 MHz. It is about 33% faster than [[SlowROM]]. FastROM is a property of the ROM chip itself and not the board it is soldered onto.<sup>[2]</sup> When the [[5A22]] is operating at fastROM speed, there are 6 [[master clock]] cycles per CPU [[machine cycles]]. | '''FastROM''' is 3.58 MHz and its ROM access speed is 120ns. It is about 33% faster than [[SlowROM]]. FastROM is a property of the ROM chip itself and not the board it is soldered onto.<sup>[2]</sup> When the [[5A22]] is operating at fastROM speed, there are 6 [[master clock]] cycles per CPU [[machine cycles]]. | ||
FastROM speeds only apply to the upper halves of banks $80-bf and all of banks $c0-ff.<sup>[1]</sup> | FastROM speeds only apply to the upper halves of banks $80-bf and all of banks $c0-ff.<sup>[1]</sup> | ||
The [[SAS]] cannot use FastROM.<sup>[3]</sup> Games which utilize fastrom should indicate this at bit 4 of FFD5 of the cartridge header.<sup>[4]</sup> | The [[SAS]] cannot use FastROM.<sup>[3]</sup> Games which utilize fastrom should indicate this at bit 4 of FFD5 of the cartridge header.<sup>[4]</sup> | ||
[[File:master_clock_divider_speeds.png]] | |||
=== See Also === | === See Also === | ||
* [[List of FastROM Games]] | * [[List of FastROM Games]] | ||
* [[420Dh]] | |||
=== External Links === | === External Links === | ||
Latest revision as of 17:08, 19 August 2024
FastROM is 3.58 MHz and its ROM access speed is 120ns. It is about 33% faster than SlowROM. FastROM is a property of the ROM chip itself and not the board it is soldered onto.[2] When the 5A22 is operating at fastROM speed, there are 6 master clock cycles per CPU machine cycles.
FastROM speeds only apply to the upper halves of banks $80-bf and all of banks $c0-ff.[1]
The SAS cannot use FastROM.[3] Games which utilize fastrom should indicate this at bit 4 of FFD5 of the cartridge header.[4]
See Also
External Links
- https://gbatemp.net/threads/romhacker-kandowontu-converts-more-than-80-snes-titles-into-fastrom-improving-their-performance.629133
- "High Speed Required?" checkbox on page 1-2-9 of Book I of the official Super Nintendo development manual
References
- Near, https://forums.nesdev.org/viewtopic.php?t=9585
- Bregalad, lbid.
- caution 3.3.6.1 on page 1-3-4 of Book II of the official Super Nintendo development manual
- http://problemkaputt.de/fullsnes.htm#snesmemorycontrol