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
