Plug and Play RS-232 Connection for Teletype Model 33

General discussions related to the Altair 8800 Clone

Plug and Play RS-232 Connection for Teletype Model 33

Postby AltairClone » October 7th, 2018, 4:14 pm

I've developed a small board that provides a plug and play connection between a Teletype Model 33 and an RS-232 serial port. Here's a link to a video that demonstrates the new board. (If you don't want to watch the whole video, start watching at the 4:20 mark in the video.)

https://youtu.be/PNbo46Yw92M

The new board plugs directly onto the P2 connector in the rear of the Model 33 Teletype where it picks up the transmit and receive data loops and also picks up power from the 48vac supply provided on the connector. The RS-232 connection is via an RJ-14 modular jack. Modular DB-25 and DB-9 connectors for the other end of the cable are still readily available.

The board uses SMT components and the 16 pin switching regulator has 0.5mm lead spacing. In addition, the back of the regulator (inaccessible with a soldering iron) is a large ground pad and must be soldered to the board for proper thermal conduction. For these reasons, the board will have to be pre-assembled by an SMT assembly house.

Pricing will be $40-$70 depending on how many boards I run. If you are seriously interested in buying one of these boards, please contact me at deramp5113 followed by ASCII 0x40 followed by the yahoo domain name so I can get a count started and run the first batch as soon as possible.

Mike
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Re: Plug and Play RS-232 Connection for Teletype Model 33

Postby toml_12953 » October 10th, 2018, 10:12 am

While I'm waiting for the board itself to become available, I ordered the modular plugs to go with it. I ordered both DE-9 and DB-9 connectors since I'll be swapping between the Altair Clone and a PC. The wires of the connectors aren't in the shells, though. You have to plug them in so I need to know the pinout of the board so I can get these assembled and ready.

P.S. Any progress on either the Kenbak-1 or IMSAI? How about an Altair 8800B front panel for the Clone? Am I ever satisfied? Heck no! :)
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Re: Plug and Play RS-232 Connection for Teletype Model 33

Postby AltairClone » October 10th, 2018, 8:05 pm

toml_12953 wrote:The wires of the connectors aren't in the shells, though. You have to plug them in so I need to know the pinout of the board so I can get these assembled and ready.


I’ll be putting together some instructions for the interface board that will include an illustration of how to determine modular connector wiring. Pin numbers and wire colors are ambiguous with phone wiring depending on whether you’re a telephone or a telephone jack - much like RS-232 signal names are confusing depending on whether you’re DCE or DTE.

Mike
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Re: Plug and Play RS-232 Connection for Teletype Model 33

Postby toml_12953 » November 3rd, 2018, 8:56 pm

My adapter arrived today. Great job! It looks so much neater than the four wires, screw terminal bar, current-loop to RS-232 adapter and power supply wall wart that I was using. I'm sure it'll be a heckuva lot more reliable, too. The DB-25 adapter worked perfectly right off the bat with the Altair Clone. My modular DE-9 adapter colors were reversed from your diagram and I hooked it up wrong (key up instead of down) at first. Once I got all the correct wires in the right holes, I fired up my PC and...nothing. It turned out I had my terminal program set for COM1: and the plug in COM2: Arrgh! I changed TeraTerm to use the correct COM port and then I could communicate with the Teletype with no problem. Now I just need to swap the modular DE-9 with the DB-25 when using either the PC or the Clone.

Thanks for a fantastic product (as usual!)

Tom L
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Re: Plug and Play RS-232 Connection for Teletype Model 33

Postby wheagy » November 13th, 2018, 9:19 pm

Hi,

Are the pinouts/wiring diagrams available yet for the RJ14 and DB9/25 connectors? I ordered a board the other day and will need to wire a couple connectors.

Thanks!

Win
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Re: Plug and Play RS-232 Connection for Teletype Model 33

Postby AltairClone » November 13th, 2018, 10:26 pm

wheagy wrote:Are the pinouts/wiring diagrams available yet for the RJ14 and DB9/25 connectors? I ordered a board the other day and will need to wire a couple connectors.


Yes, here’s the manual for the adapter http://deramp.com/downloads/teletype/TT ... Manual.pdf

Mike
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Re: Plug and Play RS-232 Connection for Teletype Model 33

Postby wheagy » November 17th, 2018, 4:20 pm

Hey Mike,

The PnP card for my ASR-33 showed up yesterday. Tested today and it works great!

Quick question. Do you know if there is an easy way to have both a 9600 baud terminal (via a Raspberry Pi) and the ASR-33 connected at the same time? Can they run at different baud rates? I messed around with the serial port config, but have not been able to get either my RPi or the ASR-33 to work on anything other than port 1. If not, is there a quick, easy way to switch from the ASR-33 back to the RPi at a higher baud rate to do some quick things, then back to the ASR?

Thanks,

Win
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Re: Plug and Play RS-232 Connection for Teletype Model 33

Postby AltairClone » November 17th, 2018, 9:46 pm

CP/M 2.2b supports IOBYTE which lets you easily swap between consoles. If you set ports 1 and 2 on the Clone to be the two ports on an 88-2SIO with the Teletype on port 1 and the pi on port 2, then...

The system will boot to your Teletype as console. To switch the console to the pi, type:

A>STAT CON:=UC1:

To go back to the Teletype, type:

A>STAT CON:=CRT:

TYPE the IOBYTE.TXT file on the CP/M 2.2b disk for more info.

Mike
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Re: Plug and Play RS-232 Connection for Teletype Model 33

Postby wheagy » November 18th, 2018, 3:39 pm

I gave this a quick try today, and while the commands seemed to be accepted, nothing changed. The ASR was still the primary input device. I'm running 59K CP/M VERSION 2.2MITS (07/28/80), so maybe that's not correct. I'll mess with it more. I also did not have the IOBYTES.TXT file on B:, so I suspect I don't have the correct version of CP/M running.

For a quick hardware fix, I connected to switch box. All I need to do it switch between the RPi and the ASR-33 and then change baud rates.

Thanks Mike,

Win
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Re: Plug and Play RS-232 Connection for Teletype Model 33

Postby AltairClone » November 18th, 2018, 3:47 pm

It has to be CP/M 2.2b, Burcon CP/M does not support IOBYTE.

See http://altairclone.com/downloads/cpm/CPM%202.2/CPM%202.2B/

Mike
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