Reading and archiving a box of cards for an IBM 1620

ALWAYS AVAILABLE TO READ PUNCHED CARD DECKS FOR OTHERS

I have two Documation card readers with interfaces that allows me to read punched cards and create PC files with the contents. My best one reads at 1000 cards per minute, which means that even with reloading the hopper it takes about three minutes to read an entire box (2000 cards are in a box). I built an interface into the reader with a USB cable that plugs into other computers. Programs on the computer can issue a read command and collect the 12 rows x 80 columns of data as the card is read. 

Reader processing card decks to a capture program on PC

I read the decks twice and digitally compare the contents to check for errors that might have occurred during reading. I also ask the collector or other expert on the computer system to work with the digitized deck to check for the very unlikely chance that the same error happens with the same card in the deck on both runs through the reader. 

Because computer systems often use multiple encodings on punched cards, I read all decks in a lossless binary format that records the holes in all twelve rows for each card column, rather than converting to the Hollerith characters that are the most common encoding. 

For example, the IBM 1130 does use Hollerith for most cards, but it has several binary formats that can be employed. In addition, data cards for applications are free to set up any encoding they wish, thus a card may intermix Hollerith characters in some columns with other encodings in different columns. 

One method uses twelve rows of one column plus four of the second column for a single 16 bit binary word, then continues with the remaining eight bits in the second column plus the first eight rows of the third column for a second 1130 word. Finally, the last four rows of the third column and all twelve rows of the fourth column are combined to form the third 1130 word. This uses four columns per three 1130 words. Another format uses two columns per 1130 word, wasting four rows of the pair thus is a less dense storage format.  

By recording the cards in the lossless format digitally, the recipient is free to interpret any column of any card as justified. Once can interpret as Hollerith and then store an ASCII equivalent character in a file. Some of the glyphs used with IBM systems don't exist in ASCII but there are Unicode representations that can be used, as long as the programs that manipulate the files are Unicode capable. On the 1130, for instance, IBM uses the cents sign and a logical not character, which do not exist in ASCII. Record, group and word marks are other glyphs that were used in older IBM systems which do not exist in ASCII. 

IBM 1620 ENTHUSIAST HAD DECKS INCLUDING SNOBOL AND ALGOL

A box arrived with decks which included the Algol and the Snobol languages for the 1620 system. These cards mostly had sequence numbers in the last columns of each card which serves as yet another validation of correct sequencing and accurate reading. We did discovers a few sections that were misplaced in the box, for example a 42 card program that was stuck in the middle of another longer deck, but that could be corrected digitally. 

BOXES FROM ANOTHER COLLECTOR COMING NEXT WEEK

A different collector is sending me two boxes, which contain quite a few decks of various sizes. When those arrive I will read them and send them back to the collector. Often the digitized files are also shared with other enthusiasts allowing them to run the newly captures programs on simulated computers or their own restored mainframes.