Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!uunet!munnari.oz.au!uniwa!andreww
From: andreww@uniwa.uwa.oz (Andrew John Williams)
Newsgroups: comp.arch
Subject: Re: Bitfield instructions--a good idea?
Message-ID: <1991Apr26.140902.18773@uniwa.uwa.oz>
Date: 26 Apr 91 14:09:02 GMT
References: <1991Apr15.193425.3436@waikato.ac.nz> <712@seqp4.UUCP>
Organization: University of Western Australia
Lines: 13

Not really anything to do with this - but hows this for 'orrible...
I picked up the 1980 Nat Semi MOS book recently, and had a look at the
COPS420 (or whatever it was) specs. No shift instruction. The way they
suggested was to swap the accumulator out to the shift register (also
connected to the outside world) and wait. The shift register was
syncronised to the instruction cycle, so to shift one bit you swapped A
back in the next instruction. For a 2 bit shift, you inserted a NOP (or
other such useful instruction). Don't worry though - the maximum delay
was 4 instructions, 'cos thats how big A was. And people complain about
the 8086!

John West (stealing Andrew's account)
Do fish need aqualungs?