It doesn't use any proper IBM codepage (such as EBCDIC 37 or EBCDIC 1047). > From the linux side, dd(1) has blocking/unblocking and EBCDIC/ASCII conversions as well.ĭd's built-in EBCDIC/ASCII conversion is terrible. Of all the programs I've worked on since then - many of them massively more complex - this one sticks in my mind as something I'm proud of. Now it would read the first card into the first buffer and print it, and while it printed read the next card into the second buffer, then print from that buffer while reading the next card after, and so forth. I looked at the code and found there were a few bytes left, just enough to make the print program double buffered. Only then it read the next card, printed that card, and so on. It read a card, then printed the card and waited for that print line to finish because it was printing directly from memory. Put this card at the front of a deck, and it would read the rest of the cards in the deck and print them on the line printer one by one.īut it was slow. The Sigma 5 had a speaker you could toggle with an instruction, so one popular single card program toggled the speaker in a way that sounded like bird chirps.Īnother popular card was a simple print program. Naturally, we tried to see what we could do with just a single card! This card loaded the actual program from the next group of cards, and then that program would read and process the rest of the deck. ![]() To run a batch job, you made a deck of cards with a boot loader card at the front. I guess they figured I would at least make sure the building was secure, and maybe do something interesting and useful with the machine. The fun part was that Transdata didn't offer their timesharing service at night! So the Sigma 5 was mine to do whatever I wanted with it. At the end of the school year Transdata hired me as "night operator" working the graveyard shift for $2/hour. My high school had a Teletype machine with an account on this timesharing service. My first personal computer was a Scientific Data Systems (SDS, later Xerox) Sigma 5, owned by Transdata in Phoenix, Arizona, in the summer of 1969.
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