I recall around 1980, the "A" machine at Purdue University Electrical Engineering, a PDP-11/70
running Version 7 Unix had a RS04 drum drive used for swap. It was getting long in the tooth and
when a power failure occurred, someone would have to get a wrench to help spin it up as the head
lubricant was no longer as good as it once was...
--tom
On 4/15/24 11:33, Mike Katz via cctalk wrote:
There was drum storage for the early PDP-8 the "Straight 8", PDP-9 and PDP-10. Each drum stored
32,768 words. Up to 8 of them could be connected for a total storage of 262,144 words of storage.
IBM made a 5BM drum storage unit that was the side of a small refrigerator: The RAMAC's disk
storage unit, the IBM 350, weighed over a ton, had to be moved around with forklifts, and was
delivered via large cargo airplanes. It stored approximately 5MB of data: *five million 8-bit
characters on fifty 24-inch-diameter disks*, a form of drum memory.
On 4/15/2024 11:06 AM, Douglas Taylor via cctalk wrote:
At the VFC East just a few days ago a young man came up to me, I had a PDP11/53 on display, and
showed me pictures of his 11/45 and PDP-8 that he had just acquired and needed to learn about.
It was impressive, he said the 11/45 was missing the memory boards. If he shows up here on the
list please help him. To me, it look like he had stumbled into a Unicorn.
Doug
On 4/13/2024 5:26 PM, Christopher Zach via cctalk wrote:
Was reading the Wikipedia article on Drum memories:
https://en.wikipedia.org/wiki/Drum_memory#External_links
And came across this tidbit.
As late as 1980, PDP-11/45 machines using magnetic core main memory and drums for swapping were
still in use at many of the original UNIX sites.
Any thoughts on what they are talking about? I could see running the RS03/RS04 on a 11/45 with
the dual Unibus configured so the RS03's talk to memory directly instead of the Unibus, but
that's not quite the same as true drum memory.
Closest thing I remember was the DF32 on a pdp8 which could be addressed by word as opposed to
track/sector.
Thoughts?
C
