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Adding an IBM 1407 work-a-like
to the Connecticut 1401
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Background & Blog

updated through May 14, 2010

"Our" "Connecticut" 1401 was used by "Buzz" Bellefleur as an accounting machine for nearby country Connecticut clubs.

Buzz apparently felt the need for more than 16,000 characters of memory, and/or wanted to play. So his CE connected a CPM based microcomputer to the 1401 through the existing 8 bit wide 1401 papertape reader/punch channel. This gave Buzz access to another 64K characters of a faster than tape memory, and/or a play ground.

In 2010, Bill Newman and Stan Paddock struggled to
- figure the interface rules for this channel
- make an interface card between the 1401 and a PC.
They succeeded - now what ?

Make the 1401 an interactive machine of course !! Why not?

So Bob Erickson offered up a semi-working transmitting typewriter, which he has since made reliable.

George Ahearn, Bob Erickson, Jim Hunt, Doug Martin, Bill Newman, and Stan Paddock are working (spring 2011) to make an IBM 1407 Console work-a-like. They are using an arduino card to handle the translations, timing, interfaces etc.

BLOG: - most recent near here
- May 14, 2011
- May 8, 2011

May 14, 2011 from Stan

After you left, Bill used one of our many DB-25 female sockets to tie the four scan lines and the first four key lines to his prototype board.

The first thing we found was we had two of the key lines mixed.

Then we found the third contact wanted to stay on and the key associated with the 'N' key was stuck on.

Other keys worked as designed.

Bob Erickson worked on the typewriter today and fixed the stuck key switches.

When we attach the real connector, all of the keyboard connectors should work.

As to weather we have built the correct keystem to ASCII character, we will see about that.

When the contacts all work, we can start on the solenoids.

May 8, 2011
Sent: Sunday, May 08, 2011 10:23 AM
Subject: Re: IBM1407Rev7.xls


The interface board is showing signs of life for both input and output now. Time to attach the DB25 plugs. For now, I will wire what I can on the first DB25, and integrate the switch sense part of the driver into George's code.

I will follow the IBM1407Rev7.xls spreadsheet from Stan for plug wiring on the switch sense side. The only variable in my case is which way the counters shift. I will wire it to the board so that the tables that Stan has created can be used directly as the look up table in the driver software. Also, I am assuming that ModelBTable2.xls is the most recent stem codes definition, and that where its blank for the row entry is really a "1", meaning the uppermost row of least most of the time? - CR/enter is certainly not in a row... I don't think I need it for wiring the plugs.

Also, for those that have not discussed this with Stan, realize that this first DB25 will have hot pins on it eventually - those unused pins in the spreadsheet will wind up with the electromagnet high side voltages controlling the 5 "state" magnets - CR, shift, unlock, space, tab.

Stan...I guess "next" happens when we can put the EM assembly back into the typewriter to verify exactly which key goes to which electromagnet? So, I will not wire the second DB25 yet.

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