On Thu, Jun 16, 2016 at 11:55:53AM -0400, James Knott via talk wrote:
Data General Nova & Eclipse computers had a choice of AC power or various clock rates derived from a crystal. The crystal wasn't all that accurate, but normally AC is.
It would be pretty accurate for sure.
The Data General Nova predates microprocessors. It was first build around 1969, IIRC. The Eclipse, while a later generation, used the same basic I/O board, which included the RTC circuits, along with serial port for the console and ports for the paper tape punch & reader.
Yeah that would be old enough to such a thing.
Incidentally, one thing I did was modify those boards from 20 mA current loop to RS-232 for the console and also replaced the fixed crystal serial port clock (you had to change the crystal to change speeds) with a baud rate generator chip that used a colour burst crystal to generate a variety of baud rates. With the 2 mods, those boards moved from 110 b/s Teletypes, to 9600 b/s CRT terminals for the console.
That's a nice improvement. -- Len Sorensen