🚀 go-pugleaf

The discs on the English Electric KDF9 spun at
constant speed but had a variable number of
sectors per track.  The gory details:
From: firth@sei.cmu.edu (Robert Firth)
Path: sei.cmu.edu!firth

speed: 1000 rpm
discs: 16 (+ 2 for control)

read arms: each arm had 4 heads above and
4 below the platter, and could be moved to
64 positions, giving 256 tracks per surface
or 512 per disc.

blocking:  The inner half of each
surface had 8 sectors per track and the outer
half had 16; each sector was 40 words and
each word was 48 bits.  Total capacity was
therefore about 3.9 Mword.

Transfer rate was 10600 word/sec for the
outer zone and half that for the inner zone;
average latency was about 240ms.

It was a beast to program, too!