6 Dec
2014
6 Dec
'14
12:46 p.m.
NOTE: In contrast with modern marketing, Seagate did
NOT try to
"maximize" the numbers by changing units nor using extraneous
"significant" digits.
They called the 506 a "5 Megabyte drive", NOT "5.33" nor
"5.08".
They called the 412 a "10 Megabyte drive", NOT "10.4" nor
"10.16".
I believe the last 2 digits of those model numbers was the unformatted capacity in some
flavour of megabytes. As well as the ST412 (which had 2 platters, 4 heads), there
were the less common ST406 (one platter, 2 heads) and ST419 (3 platters, 6 heads).
I guess it was a bit over 6 megabyes per platter, so by the time you had 3 of them
it rounded to 19 megabytes unformatted.
The ST406 and ST419 were used in the HP9133V and 9133XV respectively where the
suffix letters helpfully give the formatted capacity in roman numerals.
-tony