The "teh" at 12:40 for like a minute just glared at me and was all I could see. Haha, amazing breakdown, so fun to see someone revisit all this years later.
You need to run ground wires between the connections and twist them all together to reduce noise and reflection on your custom cable, there is a reason cables are designed that way
It was even worse in workplaces where there's no way to identify the cable wiring by any markings, no meter available to check the pinout, and there's a tangle of various things from straight thru, null crossover, non standard with some pins not wired up, non standard not even meant for RS232, and you just have to go through them all until something works or you blow something up. Then of course you find one that works but it's only 3 feet long and you need the 25 foot one
One subtle thing that may prove to be useful to solving your mystery problem: on those sportsters, they will half work like that if you are using a 9v dc supply. Some of the circuit is after the regulator and some of the circuit is before the regulator. The items before the regulator are expecting ac current from the supply. So, double check that the supply is ac, not dc.
Nice video :) I am looking to find a way to make a phone line simulation network for some retro computers with modems. The cable you are using you showed that you bought from the pinout you started with I believe the DE-9 to DB-25 cable you are showing is a NULL modem cable based on the connections you showed and the pinout photo you were using for a reference. Had to deal with all kinds of DB-25 and DE-9 serial ports back in the 80's and 90's with the job sites I had to go too. Which I also had a couple spare Laplink serial cables that had a DB-25/DE-9 connector pair on one side and a DE-9 connector on the other end. Plus a bag of gender changers. Oh the joys of having to deal with Apple II, Tandy, Commodore, and IBM systems back in the day lol.
Yeah a null modem cable would work directly between computer serial ports but to get the modems working I need to make them think there's a phone line. But I had one weird serial cable that didn't match pinouts of straight through or null modem so that was weird too.
Modems supply voltage on the phone line port, so all you need to do is connect the 2 modems phone line to phone line...ATDT(any number) on one ATA on the other...to simulate 2 real phone lines (to get "ring" signaling) use a cheap VOIP adaptor (Like a PAP2T) and set it for IP dialing so 1 line can directly call the other. To dial on some you have to turn off dial tone detection.
I could never get any combination of dialling and answering and configuration strings to work without providing my own current. Information scattered over the past 20 years in various forums have some people saying some modems supplied their own line current and some don’t so I’m assuming I have the ones that don’t.
@@GadgetReboot It's not that they "supply" voltage rather they output an ac audio signal through a line transformer which produces a small voltage on the line...as opposed to a lot of telephones that modulate the output resistance on the line. I have never seen or heard of a modem that modulates the resistance on the line. Also telephones need voltage on the line to operate the internal electronics, modems already have power. Maybe there are other settings that are at play ie. some modems need the dial tone detection turned off before they will operate in this manner. ATX3 I think....every modem I have ever seen had a line transformer in it. I have been connecting modems together since the 80's and it has always worked. MIND YOU in this world of many things I'm sure there are some modems that won't work like this, it's just I have never came across one...This was always a convenient way to transfer data from one platform to another..like MAC to SGI to CP/M and was the reason I did it so much back in the day.
Thinking back, thought CS stood for 'Carrier Sense' which could be turned off with one of the DIP switches so you can just dialout without waiting for a dialtone. Then there's no need for the 9v battery and such additional hardware?
All that would do at best is allow the modem to start dialing without listening for a dial tone first, but the line still has to have a current loop to function unless one of the modems provides the current (I've never had one of those but they existed)
I can’t remember everything I tried right now but I remember trying things similar in concept to get it to talk. When I get a chance I will power that one up and try that command. I’m going to be getting back into the modem and phone line experiments over these cold months coming up. Thanks for the tip.
I tried ATQ0 and a few other strings while I was at it and I still can’t make it respond other than just echoing back what I type in. It’s a real mystery that it’s obviously alive but nonresponsive. I will take this project to the grave if I must!
It sounds like maybe the serial interface is alive but something else is broken so there's nothing to respond. Did you try the factory reset - 'AT&F' ?
I think that's one of the first things I tried but I'll be trying it again before I put the modem away for another while. As long as I have the other two 33.6k and 56k working, the mystery won't hold anything up. Since there is a socketed chip, I am wondering if a chip swap would fix it. Maybe similar to a motherboard's corrupted BIOS being re-flashed. If I ever get another 14.4k with identical design, I'll try swapping chips.
Hi, I have a problem for some days now and didn't find a solution yet. I want to get the rs232 ring-indicator (RI) working that I can recognize it with a little C-program and do stuff when it's on and when it'f off. I have no modem connected, instead I want a simple switch on this side who switches the ring indicator on and off. I measured over 11 kOhm from RI to ground of the serial-cable that's coming out from COM-Port1 from my computer. How much current should I give the RI to work? I tried to connect some other cables (TX for example) to RI and my multimeter says that about 1-2 mA are flowing, but with my C-program I never see that the signal changes. I give my RI positive and negative voltage, but nothing happens.
I haven’t looked it up in a while but for RS-232 I believe a logic 0 is registered when the voltage is between +3 V and +12 or maybe more, and a logic 1 for -3 V to -12 V or so. I also can’t remember if the polarity for ring indicator is active high or active low but I just did a quick test on Linux using GTK Term so that I can see the status of signals down in the bottom of the window for things like CTS RTS and ring indicator. I was using a serial to USB cable with a 9 pin serial connector on it so pin five was ground and pin nine is ring indicator. I took a 9 V battery and put minus on ground and plus on ring indicator and RI lit up in GTK term so I know that works. So depending on your set up, I would expect if TX out of the serial connector is connected to ring indicator, it would be giving appropriate voltages and trigger the ring indicator when you send data out but I haven’t tried that myself, so otherwise how are you detecting ring indicator, are you using custom software? I would use a terminal program that can show the status of ring indicator to confirm it’s not a software issue and you can also try the 9 V battery test since now I know that works.
@@GadgetReboot Wow, thanks for your superb answer! "it would be giving appropriate voltages and trigger the ring indicator when you send data out ." Ah ok, I don't know this. But with the 9 V battery you got the ring indicator lit up even when no data was sent? I have no interface to send data, that's my problem. I already hooked up even 2x old 9V batteries in series wit ground and ring, but my little c tester-program compiles without errors and open the com-port but I get nothing even when I reverse the polarity. I wired it like a half-duplex sniffer (only the picture down right is relevant): www.lammertbies.nl/comm/cable/RS-232-spy-monitor.html Update: OK, I understand it now. You mean I should send data from TV out to the same serial port to ring indicator. I will try that!
@@GadgetReboot I found out when I connect GND and the ring indicator, it's too few current that flows and signal is not detected. So I used an other pin that gives me enough current.
My experience with serial connections back 30 years ago are they are most of the time a bitch to set up. something simple turns out to be a pain in the ass. You definitely had to invest in a break-out box and just make your own cables. Then the software would do weird things with the control lines. it was one of the most screwed-up' standard rs-232' i have seen.
Just yesterday I actually located another US robotics modem power adaptor in the basement that I needed to get two modems going on the phone line simulator so I will be getting back to it. I have a bunch of plans, just need the time now.
try to get a cheap 4 line PBX for home use. the are great to work/test those old modems. you can find them in most thrift stores. you have the line. you have to dail sounds. so all is there that you need and the modem thinks its connected to the phone line.
Thrift store shopping is on the near term to do list. I’d like to get a nice old eight track player as well. I regret discarding some old stereo equipment as well as old computer equipment and now I’m trying to re-create all of that old technology.
The two modems will connect ifyou just connect the phone jacks bottom two (black and yellow) to each other. no need for battery. done it 100s of times!!
some modems support a direct connection but the ones I have don’t do that and they need a loop current. Things would be so much simpler if mine would work directly.
i have a pair of supra 2400 modems that will do that, but it's a slow transfer.. still, it's a way to get software downloaded off the internet onto an old computer that is not internet capable like old cp/m systems.
@@GadgetReboot Well the usrobitics you have in the video does work with a simple line between them. No problem, tried 10-20 modems like this over the years.
You should totally setup a pbx and get them calling one another. You could even get a pci card like this. rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F122681928992 I think the db9-db25 cable you have is probably seen esoteric config. Maybe crossover, or db25 to db9 adapter or something weird. The standoffs on the db25 that were interfering I think are because db25 was also used for parallel printer ports and such. The fixed side, the side attached to a device was the one with the socket of the standoff. ... This is why USB exists. A -> B (though things have gotten a bit more complicated.)
I can’t get the modems hooked up to a terminal right now to query any internal settings, although I am currently working on a new modem and phone line related project so within a couple of months I should be going through everything again and figuring it all out so you can keep an eye out for that video. but it also depends on exactly what you’re doing like are you using a real landline or other compatible service where you should be able to get a dialtone or something, or are you using a battery to simulate phone line current? and are you trying to dial into this phone line or answer the phone line? if you have current in the phone line whether it’s real or simulated and you try to answer with something like ATA, I would expect you would be able to hear the tones trying to answer. if you’re trying to dial and obviously there’s going be no dial tone if it’s not a real phone service, that’s where you might have trouble unless you instruct the modem to not wait for a dial tone when dialling and I forget the exact command it might be something like ATX3D and then some digits and I think that’s how I got it to try to dial without a dial tone. The new project I’m working on actually creates proper phone voltages and currents and creates dial tones and works like a regular phone line so I’m hoping it works with modems but it’ll be a couple of months.
@@GadgetReboot I'm trying to replicate your testing with a 9V battery / 9V DC psu / 12v DC PSU and / or different resistor values, but the modem won't will off-hook but it won't dial a number.. I'm in X4 settings... which is the magic? :)
Can't remember now but I will eventually be making a more permanent project and starting all over with a custom designed circuit board to get it going better.
Oddly, I have these modems (some are flaky) and DB9 to DB25 cables. Storing them in another state right now though. I suppose, if you were inclined to modernize them, you could get some MAX232 chips to convert to TTL level serial, then maybe a 40-cent MCU to bang out an ACM/USB device ... like an atmega8 using USBASP. Have also built a thing with a 9V battery that enables line detection for a friend who was trying to recover data from an old Mac. s.hswstatic.com/gif/telephone3.gif
I guess that’s sort of what that blue USB to nine pin serial interface is doing, which is how I’ve been connecting the modems up to the Mac and to an old Linux mini tower for testing right now but the end goal is to get them actually on proper nine pin serial on a 386 or 486. I also thought about getting one of those serial to Wi-Fi modem emulators to get online from an old PC wirelessly and maybe see how slow Netscape is on one of those machines. I wish I never got rid of my original external 14.4 and 28.8 modems as well as my internal 2400. I could use them all now just playing around.
Funny, as I repair and salvage old PCs, I collect modems. Never liked the Winmodems much, but will keep the USRobotics, and those that have true serial. Your Sportsters there, I would never buy because they were expensive. Saw them in the office a lot though often used in fax and dial-up banks. Remember that the init strings and bios upgrades were important to keep them compatible. A random thought: Is ISDN service still available? That was a short lived thing.
The only mode am I ever bought for myself was the $50 internal 2400 modem in the early 90s. My next one was the External US robotics 14.4 as a Christmas gift. Eventually I traded that away as part of a deal to upgrade to an external 28.8 Motorola and by then the Internet was becoming a thing and I had access to LAN connections in school so that was it for dial up modems until this past year. I think I have a radio electronics or popular electronics magazine issue talking about ISDN and it had a big corded telephone on the cover. I should flip through all those old magazines and see if there’s any project ideas. I think I have a magazine article somewhere that shows how to build your own external box with an LCD screen for call display before they came standard on home phones.
try to get a real serial port or a USB to serial that not only has the rx and tx but also all the handshake signals. and make sure it levels are the RS-232 levels (some where between +/-12 to +/- 15v) www.sparkfun.com/tutorials/215 some modems dont work if they dont get the handshaking.
Oh no, haha, cable gender issues. XD 23 years ago I had a DD-50 cable made up for a Sun3 workstation, only to realize once I received it I specified it to be made horizontally mirrored. =|
The largest Dsub I worked with was a DC-37 pin because there was a footprint for one on the side of a solder proto board. Too many pins to hand solder. Didn't have a ribbon connector, had to use solder cup pins.
The "teh" at 12:40 for like a minute just glared at me and was all I could see. Haha, amazing breakdown, so fun to see someone revisit all this years later.
You need to run ground wires between the connections and twist them all together to reduce noise and reflection on your custom cable, there is a reason cables are designed that way
I'm old enough that I recognized your cable problem a few seconds into the video. I remember living that the hard way :)
It was even worse in workplaces where there's no way to identify the cable wiring by any markings, no meter available to check the pinout, and there's a tangle of various things from straight thru, null crossover, non standard with some pins not wired up, non standard not even meant for RS232, and you just have to go through them all until something works or you blow something up. Then of course you find one that works but it's only 3 feet long and you need the 25 foot one
thanks alot, ima play around wih some of my equipment myself. have access to a DSLAM and some cheap DSL modems. maybe ill make a vid of that.
One subtle thing that may prove to be useful to solving your mystery problem: on those sportsters, they will half work like that if you are using a 9v dc supply. Some of the circuit is after the regulator and some of the circuit is before the regulator. The items before the regulator are expecting ac current from the supply. So, double check that the supply is ac, not dc.
exactly, old good modems used AC adapters. 1/2 wave is rectified for receive, the other half wave for transmit circuits.
Nice video :)
I am looking to find a way to make a phone line simulation network for some retro computers with modems.
The cable you are using you showed that you bought from the pinout you started with I believe the DE-9 to DB-25 cable you are showing is a NULL modem cable based on the connections you showed and the pinout photo you were using for a reference.
Had to deal with all kinds of DB-25 and DE-9 serial ports back in the 80's and 90's with the job sites I had to go too. Which I also had a couple spare Laplink serial cables that had a DB-25/DE-9 connector pair on one side and a DE-9 connector on the other end. Plus a bag of gender changers.
Oh the joys of having to deal with Apple II, Tandy, Commodore, and IBM systems back in the day lol.
ATE0 will eliminate the echo of characters from the modem
Well you need a null modem cable, not all serial cable are equal, that cable is just an db25 to db9 adapter as a cable
Yeah a null modem cable would work directly between computer serial ports but to get the modems working I need to make them think there's a phone line. But I had one weird serial cable that didn't match pinouts of straight through or null modem so that was weird too.
Time to get some straight-thru cables and use B.O.B. For standard rs-232 sucks. We almost always had to make custom cables back in the day.
Modems supply voltage on the phone line port, so all you need to do is connect the 2 modems phone line to phone line...ATDT(any number) on one ATA on the other...to simulate 2 real phone lines (to get "ring" signaling) use a cheap VOIP adaptor (Like a PAP2T) and set it for IP dialing so 1 line can directly call the other. To dial on some you have to turn off dial tone detection.
I could never get any combination of dialling and answering and configuration strings to work without providing my own current.
Information scattered over the past 20 years in various forums have some people saying some modems supplied their own line current and some don’t so I’m assuming I have the ones that don’t.
@@GadgetReboot It's not that they "supply" voltage rather they output an ac audio signal through a line transformer which produces a small voltage on the line...as opposed to a lot of telephones that modulate the output resistance on the line. I have never seen or heard of a modem that modulates the resistance on the line. Also telephones need voltage on the line to operate the internal electronics, modems already have power. Maybe there are other settings that are at play ie. some modems need the dial tone detection turned off before they will operate in this manner. ATX3 I think....every modem I have ever seen had a line transformer in it. I have been connecting modems together since the 80's and it has always worked. MIND YOU in this world of many things I'm sure there are some modems that won't work like this, it's just I have never came across one...This was always a convenient way to transfer data from one platform to another..like MAC to SGI to CP/M and was the reason I did it so much back in the day.
Thinking back, thought CS stood for 'Carrier Sense' which could be turned off with one of the DIP switches so you can just dialout without waiting for a dialtone. Then there's no need for the 9v battery and such additional hardware?
All that would do at best is allow the modem to start dialing without listening for a dial tone first, but the line still has to have a current loop to function unless one of the modems provides the current (I've never had one of those but they existed)
Excellent Video!
try a obihal phone line emulator there really good for small business and it uses google voice plus its good for modems
ps i was looking for a new terminal program so you just helped me out a lot
I think I just found a db25 to db9 that has the same weird pin out. I hope I can find a cable that has the correct pinout
If it's echoing back but not giving a command response, have you tried issuing the ATQ0 (A T Q zero) command to tell it not to supress result codes?
I can’t remember everything I tried right now but I remember trying things similar in concept to get it to talk. When I get a chance I will power that one up and try that command.
I’m going to be getting back into the modem and phone line experiments over these cold months coming up. Thanks for the tip.
I tried ATQ0 and a few other strings while I was at it and I still can’t make it respond other than just echoing back what I type in. It’s a real mystery that it’s obviously alive but nonresponsive. I will take this project to the grave if I must!
It sounds like maybe the serial interface is alive but something else is broken so there's nothing to respond. Did you try the factory reset - 'AT&F' ?
I think that's one of the first things I tried but I'll be trying it again before I put the modem away for another while. As long as I have the other two 33.6k and 56k working, the mystery won't hold anything up. Since there is a socketed chip, I am wondering if a chip swap would fix it. Maybe similar to a motherboard's corrupted BIOS being re-flashed. If I ever get another 14.4k with identical design, I'll try swapping chips.
Hi, I have a problem for some days now and didn't find a solution yet. I want to get the rs232 ring-indicator (RI) working that I can recognize it with a little C-program and do stuff when it's on and when it'f off. I have no modem connected, instead I want a simple switch on this side who switches the ring indicator on and off. I measured over 11 kOhm from RI to ground of the serial-cable that's coming out from COM-Port1 from my computer. How much current should I give the RI to work? I tried to connect some other cables (TX for example) to RI and my multimeter says that about 1-2 mA are flowing, but with my C-program I never see that the signal changes. I give my RI positive and negative voltage, but nothing happens.
I haven’t looked it up in a while but for RS-232 I believe a logic 0 is registered when the voltage is between +3 V and +12 or maybe more, and a logic 1 for -3 V to -12 V or so. I also can’t remember if the polarity for ring indicator is active high or active low but I just did a quick test on Linux using GTK Term so that I can see the status of signals down in the bottom of the window for things like CTS RTS and ring indicator.
I was using a serial to USB cable with a 9 pin serial connector on it so pin five was ground and pin nine is ring indicator. I took a 9 V battery and put minus on ground and plus on ring indicator and RI lit up in GTK term so I know that works.
So depending on your set up, I would expect if TX out of the serial connector is connected to ring indicator, it would be giving appropriate voltages and trigger the ring indicator when you send data out but I haven’t tried that myself, so otherwise how are you detecting ring indicator, are you using custom software? I would use a terminal program that can show the status of ring indicator to confirm it’s not a software issue and you can also try the 9 V battery test since now I know that works.
@@GadgetReboot Wow, thanks for your superb answer!
"it would be giving appropriate voltages and trigger the ring indicator when you send data out ."
Ah ok, I don't know this. But with the 9 V battery you got the ring indicator lit up even when no data was sent? I have no interface to send data, that's my problem. I already hooked up even 2x old 9V batteries in series wit ground and ring, but my little c tester-program compiles without errors and open the com-port but I get nothing even when I reverse the polarity. I wired it like a half-duplex sniffer (only the picture down right is relevant): www.lammertbies.nl/comm/cable/RS-232-spy-monitor.html
Update: OK, I understand it now. You mean I should send data from TV out to the same serial port to ring indicator. I will try that!
@@GadgetReboot I found out when I connect GND and the ring indicator, it's too few current that flows and signal is not detected. So I used an other pin that gives me enough current.
My experience with serial connections back 30 years ago are they are most of the time a bitch to set up. something simple turns out to be a pain in the ass. You definitely had to invest in a break-out box and just make your own cables. Then the software would do weird things with the control lines. it was one of the most screwed-up' standard rs-232' i have seen.
Follow-up video!
Just yesterday I actually located another US robotics modem power adaptor in the basement that I needed to get two modems going on the phone line simulator so I will be getting back to it. I have a bunch of plans, just need the time now.
@@GadgetReboot Good stuff. Yes, time is the one thing that everyone seems to have little of.
try to get a cheap 4 line PBX for home use. the are great to work/test those old modems. you can find them in most thrift stores.
you have the line. you have to dail sounds. so all is there that you need and the modem thinks its connected to the phone line.
Thrift store shopping is on the near term to do list. I’d like to get a nice old eight track player as well. I regret discarding some old stereo equipment as well as old computer equipment and now I’m trying to re-create all of that old technology.
i know the feeling. getting rid of old stuff when you where young and now re-grating that you had thrown it out.
is it easy to setup pbx?
The two modems will connect ifyou just connect the phone jacks bottom two (black and yellow) to each other. no need for battery. done it 100s of times!!
some modems support a direct connection but the ones I have don’t do that and they need a loop current. Things would be so much simpler if mine would work directly.
i have a pair of supra 2400 modems that will do that, but it's a slow transfer.. still, it's a way to get software downloaded off the internet onto an old computer that is not internet capable like old cp/m systems.
@@GadgetReboot Well the usrobitics you have in the video does work with a simple line between them. No problem, tried 10-20 modems like this over the years.
You should totally setup a pbx and get them calling one another. You could even get a pci card like this. rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F122681928992
I think the db9-db25 cable you have is probably seen esoteric config. Maybe crossover, or db25 to db9 adapter or something weird.
The standoffs on the db25 that were interfering I think are because db25 was also used for parallel printer ports and such. The fixed side, the side attached to a device was the one with the socket of the standoff. ... This is why USB exists. A -> B (though things have gotten a bit more complicated.)
Hi, can you tell me the settings you had with a at&V ? With only one modem and this settings, my modem still cannot
get the hook off ;(
I can’t get the modems hooked up to a terminal right now to query any internal settings, although I am currently working on a new modem and phone line related project so within a couple of months I should be going through everything again and figuring it all out so you can keep an eye out for that video.
but it also depends on exactly what you’re doing like are you using a real landline or other compatible service where you should be able to get a dialtone or something, or are you using a battery to simulate phone line current?
and are you trying to dial into this phone line or answer the phone line?
if you have current in the phone line whether it’s real or simulated and you try to answer with something like ATA, I would expect you would be able to hear the tones trying to answer.
if you’re trying to dial and obviously there’s going be no dial tone if it’s not a real phone service, that’s where you might have trouble unless you instruct the modem to not wait for a dial tone when dialling and I forget the exact command it might be something like ATX3D and then some digits and I think that’s how I got it to try to dial without a dial tone.
The new project I’m working on actually creates proper phone voltages and currents and creates dial tones and works like a regular phone line so I’m hoping it works with modems but it’ll be a couple of months.
@@GadgetReboot I'm trying to replicate your testing with a 9V battery / 9V DC psu / 12v DC PSU and / or different resistor values, but the modem won't will off-hook but
it won't dial a number.. I'm in X4 settings... which is the magic? :)
Whats the maximun lenght you could connect?
Can't remember now but I will eventually be making a more permanent project and starting all over with a custom designed circuit board to get it going better.
@@GadgetReboot That would be great. I am thinking in replicating. My expertise is limited, but i'll get there!
Oddly, I have these modems (some are flaky) and DB9 to DB25 cables. Storing them in another state right now though. I suppose, if you were inclined to modernize them, you could get some MAX232 chips to convert to TTL level serial, then maybe a 40-cent MCU to bang out an ACM/USB device ... like an atmega8 using USBASP.
Have also built a thing with a 9V battery that enables line detection for a friend who was trying to recover data from an old Mac. s.hswstatic.com/gif/telephone3.gif
I guess that’s sort of what that blue USB to nine pin serial interface is doing, which is how I’ve been connecting the modems up to the Mac and to an old Linux mini tower for testing right now but the end goal is to get them actually on proper nine pin serial on a 386 or 486.
I also thought about getting one of those serial to Wi-Fi modem emulators to get online from an old PC wirelessly and maybe see how slow Netscape is on one of those machines.
I wish I never got rid of my original external 14.4 and 28.8 modems as well as my internal 2400. I could use them all now just playing around.
Funny, as I repair and salvage old PCs, I collect modems. Never liked the Winmodems much, but will keep the USRobotics, and those that have true serial. Your Sportsters there, I would never buy because they were expensive. Saw them in the office a lot though often used in fax and dial-up banks. Remember that the init strings and bios upgrades were important to keep them compatible.
A random thought: Is ISDN service still available? That was a short lived thing.
The only mode am I ever bought for myself was the $50 internal 2400 modem in the early 90s. My next one was the External US robotics 14.4 as a Christmas gift. Eventually I traded that away as part of a deal to upgrade to an external 28.8 Motorola and by then the Internet was becoming a thing and I had access to LAN connections in school so that was it for dial up modems until this past year.
I think I have a radio electronics or popular electronics magazine issue talking about ISDN and it had a big corded telephone on the cover. I should flip through all those old magazines and see if there’s any project ideas.
I think I have a magazine article somewhere that shows how to build your own external box with an LCD screen for call display before they came standard on home phones.
try to get a real serial port or a USB to serial that not only has the rx and tx but also all the handshake signals. and make sure it levels are the RS-232 levels (some where between +/-12 to +/- 15v) www.sparkfun.com/tutorials/215
some modems dont work if they dont get the handshaking.
_No dialtone_
cisco special cable :)
You might want to wiki a null-modem. Just saying.
Oh no, haha, cable gender issues. XD
23 years ago I had a DD-50 cable made up for a Sun3 workstation, only to realize once I received it I specified it to be made horizontally mirrored. =|
The largest Dsub I worked with was a DC-37 pin because there was a footprint for one on the side of a solder proto board. Too many pins to hand solder. Didn't have a ribbon connector, had to use solder cup pins.
Uh-boat?
it’s boot. A-boot.