On 8 Aug 2004 at 21:42, Tony Duell wrote:
> So the LED is dark if the machine is off, on steadily if the machine
> is on and no error (555 is held reset, so the output is low all the
> time), and blinks (controlled by the 555) if there's an error.
The chief electrical engineer at our company in the 1980s was a fellow who
excelled at making components in his designs do two or three jobs each.
It's an artistry that HP displayed, as you indicate.
> I can't easily reproduce the schematic in ascii-art, and I don't have
> a scanner, but if anyone is seriously interested I will see what can
> be done.
The schematic for the HP 64000 circuit appears on page 8-41 of:
http://www.bitsavers.org/pdf/hp/64000/64100-90910_64100svc_Dec83.pdf
...and it's described on page 8-13.
-- Dave
Received on Tue Aug 10 2004 - 10:40:17 BST