9 Nov
2010
9 Nov
'10
1:15 a.m.
From: Johnny Billquist <bqt at softjar.se>
Gah. I have no idea what PPU mean, nor PP.
You're probably just not old enough.
In the 50s the main processor was called the CPU (Central Processing Unit) to
differentiate it from the various PPUs, (Peripheral Processing Units). The first machine I
programmed, the IBM 7094 had a CPU and two PPUs, one to read cards and write the images to
tape transports, which would then be switched over to the CPU to read, compile and execute
the job and write the results back to another tape transport which then got switched to
the other PPU which then transferred the tape image to a line printer.
Somehow now (when most peripherals have embedded processors which could be called PPUs) we
seem to have stopped using the term.