11 Feb
2023
11 Feb
'23
3:09 a.m.
On 2/10/23, Bakul Shah <bakul(a)iitbombay.org> wrote:
Somewhat related: there was enough RF leakage when the Fortune motherboard
was not in the case. I could "tune into it" near a Jazz FM station.
Stan Rabinowitz, longtime member of DEC's PDP-8 software group,
discovered that the same could be done with the PDP-8. He wrote a
program to play music on the PDP-8 that way.
That was
quite useful because the noise pattern changed depending on what the system
was doing.
Back when I was in grad school my hearing was keen enough that I could
hear the high-pitch noise of television set vertical retrace and
acoustic burglar alarm systems. The power supply on the VAX-11/780
emitted a steady sound at about 15KHz, which I could hear. The pitch
varied depending on what the system was doing. There was a particular
sequence of pitch changes when the spooling system was about to start
a print job. I used to astound people by pointing at the line printer
a second or two before the print job started.
-Paul W.