Home  |  Contents 

Microcontroller and PC projects
  Forum Index : Microcontroller and PC projects         Section
Subject Topic: daisywheel typewriter printer mod Post ReplyPost New Topic
Author
Message << Prev Topic | Next Topic >>
chronic
Guru
Guru


Joined: 21 January 2012
Location: Australia
Online Status: Offline
Posts: 591
Posted: 16 April 2018 at 9:21pm | IP Logged Quote chronic

I rescued an old daisywheel typewriter a while ago. It works, very noisily !
The intent was...yada ...yada ... anyway... it looks like it had an
interface added so as to enable use as a printer. I very vaguely
remember there were popular articles written about that, I thought one
was in ETI but I can't see it. The interface has a 25 pin connector,
maybe Centronics parallel ?(!) Anyone remember these things ?




Back to Top View chronic's Profile Search for other posts by chronic
 
VK2MCT
Senior Member
Senior Member


Joined: 30 March 2012
Location: Australia
Online Status: Offline
Posts: 114
Posted: 16 April 2018 at 9:41pm | IP Logged Quote VK2MCT

Daisywheel or Golfball ?
IBM Golfball and interface I know about.

John

Edited by VK2MCT on 16 April 2018 at 9:51pm
Back to Top View VK2MCT's Profile Search for other posts by VK2MCT
 
matherp
Guru
Guru


Joined: 11 December 2012
Location: United Kingdom
Online Status: Offline
Posts: 2156
Posted: 16 April 2018 at 10:53pm | IP Logged Quote matherp

Quote:
I very vaguely remember there were popular articles written about that


Can't help with the daisywheel but many years ago (April 1978) I had an article in issue 3 of Personal Computer World showing how to connect a teletype to a Commodore PET (110 baud, 20mA current loop) and providing 6502 machine code to allow you to print program listings and output from within a program - happy days

Back to Top View matherp's Profile Search for other posts by matherp
 
redrok
Senior Member
Senior Member
Avatar

Joined: 15 September 2014
Location: United States
Online Status: Offline
Posts: 208
Posted: 16 April 2018 at 10:54pm | IP Logged Quote redrok

Hi chronic;
chronic wrote:
I rescued an old daisywheel typewriter a while ago. It works, very noisily !
The intent was...yada ...yada ... anyway... it looks like it had an
interface added so as to enable use as a printer. I very vaguely
remember there were popular articles written about that, I thought one
was in ETI but I can't see it. The interface has a 25 pin connector,
maybe Centronics parallel ?(!) Anyone remember these things ?


I suspect it's a conventional RS-232 serial interface. That means the serial voltages are up to +- 12V or so.

To be fair there were 25pin Centronics parallel interface connector variants. Notably on the original IBM PC. But I don't think that is what you have, kind of rare.

I used to have a Brother Daisy wheel which has the standard 25 pin serial interface. It used standard ASCII protocol, and not the IBM EBDIC serial.

Kind of slow, but did very high quality printing.

redrok
Back to Top View redrok's Profile Search for other posts by redrok Visit redrok's Homepage
 
Phil23
Guru
Guru


Joined: 27 March 2016
Location: Australia
Online Status: Offline
Posts: 1492
Posted: 17 April 2018 at 8:38am | IP Logged Quote Phil23

I'd take a stab at it being serial as well.

Is the interface a 25 Pin D connector?





If so, look at the voltages on Pins 2 & 3 with respect to ground, (Pin 7).

Depending on which pin has the -12V? (or is it +12 idle), Pin 2 or 3 will indicate if it's a DTE or DCE calss device. Basically the two transmit & receive on opposite pins.

Cheers

Phil
Back to Top View Phil23's Profile Search for other posts by Phil23
 
CaptainBoing
Guru
Guru
Avatar

Joined: 07 September 2016
Location: United Kingdom
Online Status: Offline
Posts: 541
Posted: 17 April 2018 at 5:26pm | IP Logged Quote CaptainBoing

Phil23 wrote:

Depending on which pin has the -12V


You are right. "proper" RS232 Marks with -12V and is left in a marking state when idle. I am sure there are variations but I never met one.

I used to use this to steal a negative supply with a diode/capacitor pump on stuff connected to RS232 with no negative supply available

Edited by CaptainBoing on 17 April 2018 at 5:32pm
Back to Top View CaptainBoing's Profile Search for other posts by CaptainBoing
 
chronic
Guru
Guru


Joined: 21 January 2012
Location: Australia
Online Status: Offline
Posts: 591
Posted: 17 April 2018 at 10:40pm | IP Logged Quote chronic

Thank you all ! At this stage it looks most like the full rs232,
so I'll check that direction. It's a long time since I saw full RTS/CTS etc.
It was a third-party conversion so it is a bit unusual.
There is a sticker with the original service address on it - but that address has been beneath a shopping mall for decades.
Quite impressive engineering with a daisywheel and hammer etc all precisely located on a snap-to-grid using steel wire and steppers.
Originally I was thinking of using the 0.1 inch spacing for component layout on a pcb somehow, not much point now, considering the 3d printers available.
Back to Top View chronic's Profile Search for other posts by chronic
 
Quazee137
Senior Member
Senior Member


Joined: 07 August 2016
Location: United States
Online Status: Offline
Posts: 141
Posted: 17 April 2018 at 11:36pm | IP Logged Quote Quazee137


easy check if pin 25 to I think 18 is all ground it the old IBM port interface.
Back to Top View Quazee137's Profile Search for other posts by Quazee137
 
Phil23
Guru
Guru


Joined: 27 March 2016
Location: Australia
Online Status: Offline
Posts: 1492
Posted: 19 April 2018 at 8:52pm | IP Logged Quote Phil23

chronic wrote:
Thank you all ! At this stage it looks most like the full rs232,
so I'll check that direction. It's a long time since I saw full RTS/CTS etc.


So now the fun begins!

Out with the break box with the LEDs, DIP switches & jumpers, try & work out how the Hell DTR/DSR & CTS/RTS need to be wired on this occasion...

Xon/Xoff.... Might be luck & be able to use that in a very few cases...

Phil.
Back to Top View Phil23's Profile Search for other posts by Phil23
 
Quazee137
Senior Member
Senior Member


Joined: 07 August 2016
Location: United States
Online Status: Offline
Posts: 141
Posted: 21 April 2018 at 12:54pm | IP Logged Quote Quazee137

@chronic

here is a free windows tool to debug/test serial driven devices.
ComDebug

and a site with quick run down on usage of signals
Serial ref

Years ago I built a Z80 based IBM Selectric golf ball typewriter to printer
board. It had both serial and Diablo interfaces. Had 4k byte buffer expandable
to 128k with bank switching dram. The driver for CP/M was really a bios hook.
Sadly the design is in TANGO sch/pcb and all code is asm, and on 8" floppy.

Hope the test software can help see the needed pin functions.

Quazee

Edited by Quazee137 on 21 April 2018 at 12:55pm
Back to Top View Quazee137's Profile Search for other posts by Quazee137
 


If you wish to post a reply to this topic you must first login
If you are not already registered you must first register

  Search the forums using Google.
In the news...
 
Post ReplyPost New Topic
Printable version Printable version
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot delete your posts in this forum
You cannot edit your posts in this forum
You cannot create polls in this forum
You cannot vote in polls in this forum

Powered by Web Wiz Forums version 7.8
Copyright ©2001-2004 Web Wiz Guide

This page was generated in 0.1416 seconds.
Privacy Policy     Process times : 0.02, 0, 0, 0.12