Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!umich!samsung!zaphod.mps.ohio-state.edu!van-bc!rsoft!mindlink!a186
From: a186@mindlink.UUCP (Harvey Taylor)
Newsgroups: comp.sys.amiga.tech
Subject: Re: How does the blitter decode/encode MFM data?
Message-ID: <974@mindlink.UUCP>
Date: 19 Jan 90 00:41:45 GMT
Organization: MIND LINK! - British Columbia, Canada
Lines: 26

In <19804@watdragon.waterloo.edu>, ccplumb@lion.waterloo.edu (Colin Plumb)
writes:
|In article <75676@tut.cis.ohio-state.edu> Ethan R Dicks <erd@cis.ohio-
| state.edu> writes:
|>I have been poring over the RKMs and have not been able to figure this
|>out... how does the blitter convert bit pairs into bits and bits into
|>bit pairs for the MFM <-> raw data section of trackdisk.device?
|        [how it works]
|
|This gets the job done quite neatly, but doesn't use the linear stretch
|technique you want for graphics magnification.  Sorry.
|
   There is a description of this (and some disassembly) in the Abacus
 Amiga Disk Drives Inside and Out [Chapter 9].
|
|(If you want *tricky*, try doing 1,7 RLL which has a 2/3 stretch factor.
|The same interleaving technique can be used, although you have to divide
|the data into sixths and shuffle the bits together.)
|
   Have you implemented RLL on the Amiga, Colin?

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                                                -H.L. Mencken
      Harvey Taylor      Meta Media Productions
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