21 Feb
2013
21 Feb
'13
2:50 p.m.
On 2013 Feb 21, at 3:10 AM, allison wrote:
On 02/20/2013 10:14 PM, Brent Hilpert wrote:
The 680 was shortly after the first Altair, it was still part of that
era, when people were assembling there own systems from whatever they
could scrounge together. Odd baud rates and code incompatibilities
were exactly what the 680 monitor dealt with. From the code, the in-
memory rep was still ASCII and the baud rate was set for 45.45 bps.
A friend with an IMSAI paid good money for an ASR-33 at the time. At
the same time, my high school received two surplus 5-level machines
(for free I expect, as it wasn't something the physics teacher was
about to spend significant money on). It wasn't what I would call
"only a small amount cheaper".
The interest in 5-level machines quickly faded as their limitations
became apparent and the industry moved on quickly with built-in video
console/terminal support and such, but there was interest in using them.
The point is, the 680 monitor did have 5-level support.
On 2013 Feb 20, at 11:01 AM, Holger Veit wrote:
I'm not forgetting as I had one of the first Altairs, the 680 was
later. A baudot machine was only a small amount cheaper
and far slower, odd baud rate and code incompatable with the
limited software of the day. In all of LICA
(Long ISland Computer Association) one one person had a baudot
machine (for ham RTTY) and he was
interested in using the computer to replace it.
Baudot for micros was always an oddity. Am 20.02.2013 15:04, schrieb Allison:
According to the ref'd manual there is a 'Baudot'/5-level option.
To quote, page 21:
BAUDOT TELETYPE OPTION
The Baudot version of the PROM Monitor .. to support a Baudot
Teletype ..
and convert between Baudot (5-level code) and 7-bit ASCII.
The manual goes on to talk about the 5-bit character translations
and shows a layout of a simple 5-level teletype keyboard.
You guys are forgetting that one of the most affordable terminal/
consoles for the computer hobbyist in the Altair era was a 5-bit
teletype. They were obsolete and available as surplus. 8-bit
ASR-33s and the like were still current equipment and not cheap.
If you were lucky you might manage to get your hands on a 7-or-so-
year-old surplus video terminal for cheap. A current video
terminal would be another significant expense in addition to the
computer.
On 02/20/2013 04:17 AM, Holger Veit wrote:
>
> What you have to set the terminal to depends on the jumper
> settings on the board. It also depends on the monitor itself -
> there is an ACIA version which can work with 9600 8n1, but
> there is also a Baudot TTY version.
>
There is no baudot TTY option its a 20ma serial loop option
commonly used for the asr33.
This was referred to in the listing as
"Baudot". You're right,
this is not 5 bit baudot/murray code. It is bit-banging tty, in
contrast to an ACIA, though.