[sdiy] uC with mul

John Loffink jloffink at austin.rr.com
Sun Dec 30 16:07:43 CET 2001


The multiply cycle on the 68HC16 is 8 cycles.  Other micros do have the
multiply instruction, usually multi cycle instructions.  These might be
good enough depending on your application, particularly for low
frequency stuff like note generation, envelopes, LFOs, control sources,
etc., but for anything related to analog synthesis it's generally better
to have 12-16 bits of resolution to avoid stair-stepping.

John Loffink
jloffink at austin.rr.com 

-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of Byron G. Jacquot
Sent: Saturday, December 29, 2001 10:29 PM
To: synth-diy at dropmix.xs4all.nl
Subject: RE: [sdiy] uC with mul

>Motorola M68HC16 microcontroller series has a 16 bit
>multiplier/accumulator.

The "little brother" 68HC11 could also do 8*8 multiply, and (IIRC) 16/8
division.  They were both kinda slow.  I think a multiply took 12
cycles,
and the divide something amazing like 42.

Byron Jacquot




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