Modems and external dialers.

[Grant Taylor]

On 6/5/19 9:58 AM, Ethan Dicks via cctalk wrote:
> Not quite... the USD 801 ACU I keep mentioning supported dialing using 
> either RS-232 or RS-366 over the same physical port.  It was a flexible 
> device that would work with a parallel dialing controller like the DEC 
> DN11 or by just using a second serial port from your host.

Okay.  Now I'm even more confused.  I'll have to go back and re-read 
some of the links you shared.  I'd swear that the brochure mentioned 1 x 
RS-232 + 1 x RS-366 -or- 2 x RS-232 port requirement on hosts.

> The other connector was a handset connector for a standard US telephone 
> (narrow 4p4c jack).
> 
> To use this modem, you'd load and run your terminal app then pick up the 
> phone and dial the number.  When the far end answered, you'd unplug the 
> coiled cord from the handset and quickly plug it into the VICmodem before 
> the other end hung up.

So the phone played an active role in modem communications.  At least in 
so far as it converted the purely audio from the modem to telephony used 
by the PSTN.

> It did have the advantage over an acoustic coupler in that room noise 
> was not a factor

ACK

Analogues to the Line-Out to Line-In for audio recording vs speaker and 
microphone.  (Quite literally.)

> it had the advantage over a Hayes modem of cost (ISTR the VICmodem 
> was somewhere around $70 and did not require the $50 Commodore RS-232 
> "interface" (analog level shifter with DB25 port).  I did eventually get 
> that RS-232 cartridge but not for modem work.  I got it to hook my C-64 
> to other local machines for file transfer.

ACK

> Like a lot of hobbyists in the 70s and 80s, I spent a lot of time making 
> serial adapters and debugging serial comms.  It came in handy when I 
> went to work for the place that made sync serial devices.  I still do 
> most of my hacking on a Dell laptop that's old enough to have a real 
> serial port and I do use that port.  It has advantages over USB dongles 
> for some of the less-traditional uses (like 45.45 / 50 bps and 2 stop 
> bits for old teletypes).

Intriguing.  I've never done much with anything other than 9600 or 
115200 for terminal connections to equipment to configure & manage said 
equipment.



-- 
Grant. . . .
unix || die