Model T Serial Cable

Summary

The ideal cable to go from a PC to a Model 100, 102, 200, or 600, would be described as "9F/25M serial null-modem full-handshake".

That is an uncommon configuration to find in a single cable without needing adapters or needing to build it yourself custom.

The serial ports on Models 100-600 are wired DTE, the same as a com port on a PC, but with a female connector, unlike any pc.

This is a backwards configuration from everything else today. It has been suggested that maybe this is actually the original standard, and IBM came along later and changed it by putting male connectors on their PCs (probably to distinguish them from the printer port), but the standard today is that DTE ports are male. A female 25 pin port is either a parallel printer port or a DCE port on a modem.

That means that usually you always need some kind of adapter between a PC and a M100/102/200/600, because none of the normal cables you will have lying around will have the right combination of wiring and connectors.

The easiest way to connect with parts you are most likely to already have lying around, is to use a common 9F/25M Modem Cable combined with a 9M/F Null-Modem Adapter.

Ideal cables

These cables are wired null-modem, have all the connections for hardware flow-control, and the right connectors on both ends, all in one factory-molded piece. You don't need any null-modem adapters or gender-changer adapters.

C2G 03019

DCD+DSR<-->DTR

S+PG (Shield is also connected to pin 1 on the 25 pin connector, aka PG, Protective Ground)

No RI

Amphenol CS-DSNL4259MF-005

DCD+DSR<-->DTR

S+PG

No RI

Includes nuts (removable) on the 9-pin plug screws, so you can screw a usb-serial adapter together to the cable.

StarTech SCNM925FM

No DCD

No RI

Less ideal cables

These cables actually work fine for pretty much everything, including TPDD client/server connections, since there isn't even any way to *set* hardware flow control in either BASIC or TELCOM anyway.

But the hardware in Models 100-600 *can* actually do RTS/CTS, if you manipulate the UART registers yourself from a machine language program. The only software I know of that does this is HTERM. So these cables are NOT suitable for HTERM

These cables are wired null-modem and have the right connectors all in one factory-molded piece also. They don't need any null-modem adapters or gender-changer adapters.