MauriceH
Experienced Member
Have a question about old analog Modems.
In photo is the current setup with a home telephone exchange.
As a follow up on the modem setup question See Threat
Its al working, but with some typical problem that I can't figure out.
Have a PDP8M serial setup card 110Bd, than a modem 200Bd (LEM NR 200Bd) a parallel old phone to dial a number.
A Wyse-85 Terminal, 110Bd setup, an old 300Bd Datacoupler, Anderson Jacobson Model A211.
A ASR33 Teletype with build-in LEM-NR 200Bd modem (same type as with the PDP8M),also with parallel dial phone.
If in this setup I cal from PDP8M to ASR33, its working fine, good connection.
If in this setup I cal from Wyse-85 terminal to ASR33, its working fine.(Not very useful but though fun to connect them)
Then If I cal from PDP8M to Wyse-85 terminal, have no carrier detection on that Datacoupler.
At the LEM-NR200Bd attached to PDP8M , I have to switch internal a switch 1,2,3 ,seems to be a carrier tone change.
Normal its set to 1 (same setting at LEM 200Bd inside the ASR33).
For connection with Wyse-85 datacoupler, I have to set that modem to 3.
2 is an auto switch, through a 6Vdc external wire I can switch between the 2 settings 1 and 3 external.
Original that LEM modem inside ASR33 was wired that way, so with a switch on top ASR33 I could change carrier tone.
But as I had to rebuild that circuit back to original to stop ASR33 printer when using the tape reader, and stop
printer for local print, when using keyboard ASR33 with PDP8M, other wise I get double characters printed, due to
fact PDP8M is returning characters. A DIR would end up DDIIRR at ASR33 side.
As that ASR33 switch was the "Stop-Printer"and was rewired to carrier-tone switch.I reversed that.
I can not believe that a costumer had to manually select a carrier tone to call a computer, back in the day's.
Other way, when at computer side you want to sent a file to a ASR33 you first have to call by phone to ask if
carrier tone switch is set correctly.
The ASR33 has also a light "carrier-detect" .
So why is datacoupler working with LEM-Modem ASR33, at switch 1 carrier tone (Not in setting 3)
LEM to LEM both in switch 1 carrier mode.I have carrier detect at ASR33.
But when datacoupler wants to talk to PDP8M ,LEM needs to be set to other carrier tone , setting 3.
This to get Datacoupler recognise that carrier tone. (carrier detect).
Perhaps something with Host and remote carrier type of tone?
Then these are old analogue modems, But is it possible to connect them to a, say old 14k4 baseband modem?
I thought these try to pol to other modem to setup baud-rate?
Then manual Hayes codes, IBM - Modem-Setup strings.
But can't find a setting to talk to old analog modems.
Maurice.
In photo is the current setup with a home telephone exchange.
As a follow up on the modem setup question See Threat
Its al working, but with some typical problem that I can't figure out.
Have a PDP8M serial setup card 110Bd, than a modem 200Bd (LEM NR 200Bd) a parallel old phone to dial a number.
A Wyse-85 Terminal, 110Bd setup, an old 300Bd Datacoupler, Anderson Jacobson Model A211.
A ASR33 Teletype with build-in LEM-NR 200Bd modem (same type as with the PDP8M),also with parallel dial phone.
If in this setup I cal from PDP8M to ASR33, its working fine, good connection.
If in this setup I cal from Wyse-85 terminal to ASR33, its working fine.(Not very useful but though fun to connect them)
Then If I cal from PDP8M to Wyse-85 terminal, have no carrier detection on that Datacoupler.
At the LEM-NR200Bd attached to PDP8M , I have to switch internal a switch 1,2,3 ,seems to be a carrier tone change.
Normal its set to 1 (same setting at LEM 200Bd inside the ASR33).
For connection with Wyse-85 datacoupler, I have to set that modem to 3.
2 is an auto switch, through a 6Vdc external wire I can switch between the 2 settings 1 and 3 external.
Original that LEM modem inside ASR33 was wired that way, so with a switch on top ASR33 I could change carrier tone.
But as I had to rebuild that circuit back to original to stop ASR33 printer when using the tape reader, and stop
printer for local print, when using keyboard ASR33 with PDP8M, other wise I get double characters printed, due to
fact PDP8M is returning characters. A DIR would end up DDIIRR at ASR33 side.
As that ASR33 switch was the "Stop-Printer"and was rewired to carrier-tone switch.I reversed that.
I can not believe that a costumer had to manually select a carrier tone to call a computer, back in the day's.
Other way, when at computer side you want to sent a file to a ASR33 you first have to call by phone to ask if
carrier tone switch is set correctly.
The ASR33 has also a light "carrier-detect" .
So why is datacoupler working with LEM-Modem ASR33, at switch 1 carrier tone (Not in setting 3)
LEM to LEM both in switch 1 carrier mode.I have carrier detect at ASR33.
But when datacoupler wants to talk to PDP8M ,LEM needs to be set to other carrier tone , setting 3.
This to get Datacoupler recognise that carrier tone. (carrier detect).
Perhaps something with Host and remote carrier type of tone?
Then these are old analogue modems, But is it possible to connect them to a, say old 14k4 baseband modem?
I thought these try to pol to other modem to setup baud-rate?
Then manual Hayes codes, IBM - Modem-Setup strings.
But can't find a setting to talk to old analog modems.
Maurice.
