Article View: comp.sys.amiga.tech
Article #13468Re: How does the blitter decode/encode MFM data?
From: Colin Plumb
Date: Fri, 02 Feb 1990 01:50
Date: Fri, 02 Feb 1990 01:50
18 lines
1459 bytes
1459 bytes
In article <242@sunee.waterloo.edu> sjorr@sunee.waterloo.edu (Stephen_Orr) writes: >An article on this very topic (and the source of my knowledge) was written >by Betty Clay, and appears in V3 I1 of the Amiga Transactor. It is also wrong in a couple of points, most notably in asserting that GCR, due to its 4/5 data rate, achieves greater density than MFM's 1/2 rate. It does not point out the need for the two differnt bit clock rates (2us and 4us) due to the different minimum run lengths in the codes. Since it's safe to clock out MFM at twice the rate, it gets 20% more bits in the same amount of disk space. The interaction of encoding schemes and analog channel design (everything that talks to the read/write head) is a complex one. See Magnetic Recording (especially volume II, computer data storage) by C. Denis Mee and Eric D. Daniel for all the details. This three-volume set has more than you ever really wanted to know on the subject. -- -Colin
Technical Details
Message-ID:
<20446@watdragon.waterloo.edu>Path:
arc1-ca.pugleaf.net!utzoo!utgpu!watserv1!watdragon!lion!ccplumbReferences:
<75676@tut.cis.ohio-state.edu> <242@sunee.waterloo.edu>Show Full Headers
Complete Article Headers
Path: arc1-ca.pugleaf.net!utzoo!utgpu!watserv1!watdragon!lion!ccplumb From: ccplumb@lion.waterloo.edu (Colin Plumb) Newsgroups: comp.sys.amiga.tech Subject: Re: How does the blitter decode/encode MFM data? Message-ID: <20446@watdragon.waterloo.edu> Date: 2 Feb 90 01:50:02 GMT References: <75676@tut.cis.ohio-state.edu> <242@sunee.waterloo.edu> Sender: daemon@watdragon.waterloo.edu Reply-To: ccplumb@lion.waterloo.edu (Colin Plumb) Organization: U. of Waterloo, Ontario Lines: 18