12 Apr
2024
12 Apr
'24
2:27 p.m.
On Fri, 2024-04-12 at 16:13 -0400, Paul Koning via cctalk wrote:
Not all that fast, well, it depends on what you're
comparing with.
Given tube logic with cycle times measures in microseconds, quite
possibly serial rather than parallel organization, those acoustic or
drum memory systems weren't all that terrible.
Speaking of drum machines....
On the Bendix G-15, memory was logically 20 "long" delay lines, each of
108 words of 29 bits, and four "short" lines of four words each, 27
times faster, used for registers.
The "delay line" was not an acoustic mercury delay line. Rather, it was
implemented on a drum as a digital delay line, with data read and them
immediately written a short distance away on the same track. Data were
not retained on the drum when the machine was turned off.
It was a serial machine. Even the instructions were designed to
minimize how much had to be held in flop flops.
The machine was remarkably cost effective for its time. Being five feet
tall with a one square yard footprint, it could have been a home
computer, but as far as I know, the only "home" version was one that
the designer, Harry Huskey, got. It was based on the Automatic
Computing Engine, or ACE, designed by Alan Turing. Huskey had worked
with Turing for about a year. Huskey also worked on SWAC. He did most
of the G-15 design work while he was a professor at UC Berkeley.
Nicklaus Wirth was one of his grad students. David Evans, cofounder of
Evans and Sutherland, worked for him on the G-15 project.