Alwin Henseler wrote:
>>Giovanni dos Reis Nunes <[EMAIL PROTECTED]> wrote:
>> I know that SONY HB FS-XDJ (MSX2+) and FS-XmkII (MSX2) has a speed
>> controler. I call it "fMSX for MSX" :) Using it you can reduce the
>> clock speed (ideal for games).
>
>I might be mistaken, but aren't you talking about RenSha-turbo here?
>That would be something controlling the speed of an autofire (also
>working with the space bar), but NOT doing anything with CPU clock
>speed. In fact, I don't think there are ANY MSX-machines that have
>hardware for controlling CPU clock speed built in. Not even the
>Turbo-R, this thing doesn't change clock speeds, but changes CPU's
>instead...
No, the HB-F1XDJ has a RenSha-Turbo AND Speed Controller. The Speed
Controller makes your CPU go slower. I've never seen it in action, so I
don't know for sure whether it's really the CPU that's slowed down or it's
just the VDP interrupts.
>I did figure out this about this MSX2+ hardware-controlled pause: a
>Z80 "DI" instruction seems to disable it (jippie! yes! chaka!). I'm
>not QUITE sure, check out this piece of code to make sure:
***SNIP***
>There is one big problem with this: it seems that there are various
>low-level hardware-actions that immediately re-enable the pause
>function again:
>-any VDP access, EVEN if still in "DI" state (damn..)
>-Z80 "EI" instruction (regardless of interrupt routines used)
Interesting stuff!
Greetz,
Patriek
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