Teletype ASR-33 questions and needs

[Mike Katz]

I was given an ASR-33 complete with stand, reader & punch.

This ASR-33 has been modified for RS-232 though a blue perfboard mounted in the connection enclosure (under the cover place where the dialer would be on the right side).

It has a DB25 ribbon cable coming off of this board.  The perfboard does not have a label on it that I can find.

The ASR-33 also has a 3 x 5 conductor rectangular connector coming out of the rear of the unit with 6 female contacts installed.

I was able to connect the ARS-33 to a VT-330+ at 110B 8-N-2 and send and receive on the teletype.

The punch seems to work as well.

The reader will "chatter" then the reader is put in the start position and the tape out sensor is pressed but the sprocket does not advance and the reader pins to not move.

Questions:

1. Why the reader is not advancing and the pins are not activating?  Could this be a read enable contact not being in the active position?
2. What are the pin outs of the RS-232 DB-25.  Other than TX, RX and GND
   
3. What are the pin outs of the 3 x 5 rectangular connector. I think this is the current loop and other control signals.

Does any one of the items below for sale or have a 3D model I can print:

1. Roll Paper spindle (the spindle that the roll paper spins on)
2. Paper Tape Punch Spindle (the spindle that the paper tape spins on)
3. Paper Tape Chad feed tube
4. Paper Tape Chad Box

I will be connecting this to either a PiDP-8/I or a PDP-8/E for now and eventually a PDP-8/L

Thank you,

     Mike

[Mike Katz]

Thank you 

As I said I already have it communicating with a VT-330+ for transmit & receive.  So tx, rx & ground are 2, 3 & 7.  I did have to reverse 2 & 3 between the ASR-33 and the VT-330+

My question was about the reader and connector pin outs.  And any ideas in why the reader isn't working.  and the parts I need.

On Tue, Jun 3, 2025, 1:04 AM Peter Sandilands <pe...@sandilands.vu> wrote:

RS232 has many incarnations and depends on what the builder did.

But for a guide

These are the pinouts for a DTE - Data Terminal Equipment

2 - TX

3. - RX

4 - RTS  (Request to send)

5 - CTS (Clear to send)

6 - DSR (Data set ready)

7 - gnd

8 - DCD (data carrier detect)

20 - DTR (Data Terminal Ready)

It should work with 4 - 5, 6- 20 and just 2, 3, 7

You may need to link 8 to 6, 20

If the other end is setup as DCE (Data Communications Equipment it should just work)

If the other end is DTE then you'll need to cross 2, 3 and 4, 5 and 6, 20

20ma current loop is so much easier :-)

Peter

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==========================

Peter Sandilands

Sandilands Security Pty Ltd

0439 738 371

pe...@sandilands.vu

==========================

[Steve Tockey]

I can't remember all of the gory details but ASR-33 paper tape readers require a special mod to work on PDP-8s. It has something to do with the Reader Run signal, as best as I can recall. Maybe the best source would be to contact Curious Marc and see what he can tell you on the topic. Otherwise, I have the print set for my pdp-8/e at home in Seattle but I'm in Austin, Tx most of this week. I can see if there's anything about it there when I'm home on Friday. For sure, unmodified ASR-33 readers don't work on DEC equipment.

-- steve

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