I've not tried it personally, quiet is supposedly the fastest. from: https://www.lemon64.com/forum/viewtopic.php?t=89802 ## Bus Operation Modes * Quiet (Default): The Ultimate minimizes traffic on the external expansion bus. It only asserts signals when explicitly addressing an external cartridge. This is the safest, most stable setting for standard C64 operation and general emulation, as it reduces electrical noise and prevents bus clashes. * Writes: Forces the Ultimate's bus bridge to pass write cycles through to the external cartridge port. * Dynamic: Adjusts the bus timing and address mirroring dynamically. This is required for high-speed external expansions, complex co-processors, or when using the Ultimate 64's Turbo modes alongside physical external hardware. * Dyn. & Writes: Combines both Dynamic timing adjustments and external write capabilities. Having 64mhz (or 48mhz on earlier U64) makes for some interesting projects. On 06/08/2026 18:23, Justin wrote: > What I discovered was that U64E and C64U behave slightly differently in terms of REU performance as you turbo. 8Mhz aligns with my benchmarks on C64U. I see that below that I can use the REU’s DMA to accelerate some of my crypto math, and above that the CPU outruns it. I reworked my affected crypto math libraries to have two different profiles. > > What setting alters the REU’s behavior that way? > > I am very eager for some of the fixes since firmware 3.14 for U64E to be released. In particular the writemem/temp folder garbage collection issue, which exists in the C64U firmware as well. > > Justin > >> On Aug 6, 2026, at 10:28, smf <smf_at_null.net> wrote: >> >> REU should be able to run at ~8mhz, though there are some compatibility settings that cause it to slow down to 1mhz. >> >> The Hyper Speed kernal is also incredibly fast, if you mount an image then even sector reads/writes work. >> >> I've got a project coming soon that benefits from both of them. >> >> On 06/05/2026 16:00, Justin wrote: >>> REU is also clocked to 1Mhz regardless of turbo.Received on 2026-08-11 22:00:01
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