According to the book "IBM's Early Computers" no, it used a servo
mechanism and a long cable. The same motor to move the heads in and
out as well as to move the arm from disk to disk. Detentes where used
to lock the arm and head into position. The first mention of hydraulic
actuators was with the 1301 announced in mid 1961. The 1301 features
"slider" heads that flew like modern disk heads and a head per surface,
instead of having to retract and move the arm vertically.
Paul.
On 2026-06-10 22:50, Jim Davis via cctalk wrote:
Did it have hydraulic positioners like the old CDC 3300 drives?
On Wed, Jun 10, 2026 at 6:29 PM Paul Koning via cctalk
<[email protected]> wrote:
On Jun 10, 2026, at 7:32 PM, Fred Cisin via cctalk <[email protected]>
wrote:
Didn't show up on the list, so re-sending it:
---------- Forwarded message ----------
Date: Wed, 10 Jun 2026 12:14:39 -0700 (PDT)
From: Fred Cisin <[email protected]>
Subject: [cctalk] Ramac : The real first disk drive? (Was: Floppy disk
The first known and recognized disk drive of ANY type (hard disk preceded
floppy) was the Ramac, 70 years ago, 1956
https://www.computerhistory.org/storageengine/first-commercial-hard-disk-drive-shipped/
First one shipped was to Crown-Zellerbach Paper Company
CHM says June;
EDN and Google AI (Gemini) say September 13, 1956
https://www.edn.com/ibm-intros-1st-computer-disk-storage-unit-september-13-1956/
But, Gemini seems to also hallucinate RAMAC as being a company!
"At the 1958 Worlds Fair, RAMAC showcased its revolutionary random-access
capabilities by answering world history questions in 10 different languages."
(There was no Ramac Company exhibiting at the 1958 Worlds Fair)
Ramac had fifty 2 foot diameter double sided platters, and could hold a total
of about 5MB. Modern drives can have even higher density!
I have a crashed Ramac platter, that I have made into a patio table, with the
platter under glass.
"Higher density" indeed. One of the first hard drives I used was 128 kB (DEC
RC11/RS64).
One peculiar aspect of the RAMAC is that it only had one head, or one pair, so
track switching was a lot slower than cylinder switching: it had to retract all
the way, then move the head vertically to the correct track, then seek in again
to the right cylinder.
paul
