digital equipment corporation · maynard, massachusetts
Mark Sense and Punched Cards at VCF East 2014

The retro computer hobbyist group MARCH (now VCF) hosted the Vintage Computer Festival East 2014 exhibit. I brought a PDP-8/M Computer, Wrightline hand card punch, LA100 printer, CR05 card reader, CR8F card reader, and VT100 terminal for my exhibit. I was also supposed to have a RX02 floppy drive for running the system but it got left at home. I instead used OS/8 Disk Server.

This exhibit showed punched card equipment that was used with PDP-8's and some general punched card information. Both readers I brought could read normal punched cards. The CR05 could also read mark sense cards which are marked with pencil instead of having holes punched in them. The CR8/E punched card interface for the PDP-8/E only supports reading cards.

DEC offered mark sense batch for the PDP-8 which allowed a large number of students to share one computer by preparing cards without needing anything other than the special mark sense cards and a pencil. I had used my laser printer to print on blank punch cards the special card format needed. Visitors could try writing BASIC or FORTRAN programs and running them. I had a couple people do simple BASIC programs and one do a simple FORTRAN program.

Mark sense cards could also be used for attendance. DEC also had standalone EDUsystem 30 BASIC which used a different format mark sense card than the mark sense batch BASIC. See the attendance card, and EDUsystem-30 template and basic card.

I also had a hand card punch which people could try punching a card and then I would run it through the reader. I gave them the card and a printout in block letters of what they punched on the card. I had a number of people try punching a card.

The following picture links also have descriptions of what is shown in the pictures.

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My exhibit (128K)  Programming with mark sense cards (126K)  Hand punch (121K)  Chads (124K)  Printing cards (119K)
CR05 rollers ( 84K)  First replacement attempt ( 81K)  Second replacement attempt (134K)

Card history writeup behind exhibit

Cards I used for demo. These are converted from the mark sense batch manual. I don't have an original card. I made them the color of other mark sense cards I have.
Mark sense batch FORTRAN card
Mark sense batch BASIC card
Scan of original BASIC card I got in 2023
Instructions to mark card

These people take better pictures than me.
Herb Johnson Bill Degnan Armchair arcade 1 Armchair arcade 2 Bill Sudbrink Hackaday

Card Reader Videos

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Feel free to contact me, David Gesswein djg@pdp8online.com with any questions, comments on the web site, or if you have related equipment, documentation, software etc. you are willing to part with.  I am interested in anything PDP-8 related, computers, peripherals used with them, DEC or third party, or documentation. 

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