Hitachi makes a pin and instruction compatible CPU (6309), I don¡¯t know if they make the B variant though.
This CPU can run up to 4 MHZ, where¡¯s the 6809 maxes out at 1.89 or so.
There are additional registers an instructions in the 6309 when running in enhanced mode, that offer additional features, notably performance enhancements.
However the ROMS would need to be rewritten to take advantage of the new speed, and it is highly likely a lot of peripheral hardware
Would be affected. With the higher performance, it may be possible to add new features in the same 64K addressing space, because of the extra instructions and registers. It would be a monumental effort though, and a lot of time.
No silver bullet there.
>>>
Am 15.06.2018 um 00:20 schrieb min struct
min.struct@... [xpantastic]:
?
Hello,
Would this work bring any chance to be able to
replace the 6809 CPU with an upgraded reference ?
What would happen if the CPU frequency would be 4
times the original one ?
When speeding up CPU frequency by the facor of 4,- in a synthwhere
lots of modulators are realized in software, almost everything
speeds up in relation,- LFO rate p.ex. and even the actually slowest
possible rate.
Same w/ ENV segment times (Delay, A, D & R), Ramp times,
Portamento times and so on.
No sound formerly being programmed and stored into memory would
sound the same like it does today.
I know well because they got that issue w/ the "Musitronics"
SpeedKit for the D50/550 w/ the target making the synth tighter when
playing chords.
They got it, but after they had speed up the processor by a factor
of 4? (there?s a daughterboard which fit?s the original socket,
which also offers 3 more memory banks and a 2nd/separate battery in
addition as also they replaced the original quartz making the clock
more accurate) they had to slow down those rates mentioned above to
make the synth sounding the same as it did w/ the original
processor, quartz and firmware.
Would it be possible to speed up the software
envelopes ? or some software modulation sources ?
In case of the ENVs, you want to make ?em snappier, not faster ...
that?s the Attack/Decay times and probably also slope ...
For LFOs, you might want ?em to go faster (audio rate), but want ?em
as slow as tthey originally go,- or slower in addition.
Same for Ramps.
And those things are all realized in software in Xpander/ M12
Or would it be a mess for the other controls ?
not urgently when done right.
:-)
P.
