[GTALUG] Microsoft open sources Windows Calculator

[James Knott]

On 03/17/2019 04:46 PM, Stewart Russell via talk wrote:
> I can confirm that Baudot is alive and (maybe not quite) well in RTTY
> for amateur radio. It's one of the few digital radio modes that's
> amenable to massive amplification, so 2 kW+ QRO RTTY rigs are not
> uncommon. Listen in around 14.1 MHz and you'll hear RTTY contests
> bleating away every weekend. Still around 45 baud, too. Fldigi on
> Linux can encode and decode it. 
>

Actually, 45.4 baud.  I used to run RTTY, with both Baudot and ASCII.  I
wrote the terminal software for my IMSAI 8080 and designed & built the
serial port board for it.  I designed and wired it for 8 ports, but only
had 3 installed.  I also built my demodulator, based on a couple of
magazine articles, but my Kenwood TS-820s had a built in FSK keyer, so I
didn't have to build that half of the system.

My serial board used the same 8250 UART as the IBM PC, but in a much
more intelligent manner.  Instead of each UART having it's own IRQ line,
my board shared one among all ports, in the same manner as used on
mini-computers, where 8 or 16 port boards were commonly used.  When one
UART generated an IRQ, my software would read a port to determine which
one needed service and write the same value back, to select the
appropriate UART.  In the process of testing that board, I discovered a
bug in the UART, that Western Digital didn't know about.  However, there
was an easy work around.

The software I wrote could convert between Baudot and ASCII, so that I
could copy the incoming traffic on my M35 Teletype.  It also had a few
canned messages and RY or U* generator, to create a continuous reversing
bit pattern, to help the other end tune in  the signal.  I also had
unshift on space and several other useful features in that software,
such as starting up the tape reader, on the M35, to send tapes, with
conversion to Baudot when needed.  Back in those days, you knew your
computer inside and out, because you did everything from scratch or a kit.