9 May
2017
9 May
'17
7:58 p.m.
On 2017-May-09, at 9:06 AM, Chuck Guzis via cctalk wrote:
Looking at this documents:
http://www.samhallas.co.uk/repository/telegraph/data_set_101c.pdf
I sill can't figure out what a lot of the stuff inside is for.
I've looked at one of these modems in the bottom of a 33 although not examined it in
great depth.
I expect a large part of the volume of stuff like the relays isn't really modem but
call-management sequencing & switching: on/off hook, incoming-call detect, answer
detect, originate/answer mode switching, etc.
Going from examination of another modem from the era, the modem proper can be expected to
be on the several PCB cards, modularised as filters, modulator, discriminator, 20mA loop
interface, etc.
The telephone equipment manufacturers in those days were very good at laying out and
wiring things in an exceedingly complex manner, they really liked wire bundles and dress.