🚀 go-pugleaf

In article <8445@c3pe.UUCP>, charles@c3pe.UUCP (Charles Green) writes:
> serial input channels	(mind you, this scheme would need to clock at
>   A B C D E F G H	something like 384K bps for eight 9600 bps lines...)
>   | | | | | | | |
> +-+-+-+-+-+-+-+-+-+                           +-----------------+
> |     U A R T     +---------------------------+     U A R T     |
> +-----------------+   multiplexed data line   +-+-+-+-+-+-+-+-+-+
>                                                 | | | | | | | |
> (and no, I haven't done it.  Yet.)		A B C D E F G H
> 					      serial output channels

  It's been done. Consider the Gandalf PACX IV data switch - 256 terminal
ports to 128 computer ports with _NO_ UARTS in the data path (true, there
are 4 for the "connection engine" and 2 for the console and status ports.
All the serial lines end up as bits on parallel ports which are then scan-
ned at 38.4 KBPS and copied (more or less sucessfully) to their destina-
tions.

  Here's my entry in the "silly UART trick" contest:

  The Volker-Craig VC4404 "Chat" terminal was a microprocessor-driven
replacement for the VC404 terminal. The 4404 had 2 UARTS - one for the
host's serial interface and one to receive data from the keyboard. The
KB UART had no use for the transmitted data pin. During development,
it was determined that there wasn't enough CPU power (the terminal
only had an effective 1/2 6502 CPU, as alternate cycles were given to
the display) to beep the beeper. So, they programmed the transmit side
of the KB UART for 1200 BPS and wrote x'55' characters to it to pulse
the feeper element!

	Terry Kennedy		Operations Manager, Academic Computing
	terry@spcvxa.bitnet	St. Peter's College, US
	te...@spcvxa.spc.edu	(201) 915-9381