Network 3 Controller ripe for a repro?

[IBM Portable PC]

I just noticed how simple the Network 3 Controller circuit actually is.

TRS-80 Network 3 Controller Service Manual

It's basically just an RS232 switch, with no processor or firmware. etc. The main chips also appear to be readily available still, at least on ebay.

The only change I would make is using RJ45 jacks for the slaves to save space, as only 5 pins are needed (re the Service Manual above):
Signal Ground Pin 1
Transmit Data Pin 2
Receive Data Pin 3
Request To Send Pin 4
Data Set Ready Pin 6

The host could also be a RJ45, although a DB25 somewhere would be nice. The pinout is:
Signal Ground Pin 1
Transmit Data Pin 2
Receive Data Pin 3
Request To Send Pin 4
Data Terminal Ready Pin 20
Calrrier Detect Pin 8
Clear To Send Pin 5

This video Network 3: The First Practical TRS-80 Model 12-CoCo Setup prompted this post, thanks TJBChris.

 

[shirsch]

I've been hoping someone would take this up as a project.

 

[jlang]

I would suggest you make the pinout on your RJ-45 match the pinout used for lots of other devices.
like Cisco/Juniper routers.
Then you will be able to use off the shelf cables and adapters.

 

[TJBChris]

This video Network 3: The First Practical TRS-80 Model 12-CoCo Setup prompted this post, thanks TJBChris.

Glad you liked the video! It’s a fun device to play with. There’s been some discussion about a repro here and there, and it seems like the main concern was the serial ports and size of the thing.

Shrinking it down with smaller connectors would probably help…It can be made to work with any system with a serial port and the necessary control lines, but you’d be starting from scratch when it comes to software.

The only commercial software for these that was made available is the Model III/4 software that RS sold to schools. Anything else would have to be written from scratch. Fortunately interfacing the controller itself is fairly easy.