Xref: utzoo rec.humor:18564 comp.misc:4940 Path: utzoo!attcan!uunet!lll-winken!ames!mailrus!husc6!spdcc!ima!johnl From: johnl@ima.ima.isc.com (John R. Levine) Newsgroups: rec.humor,comp.misc Subject: Re: Looking for Computer Folklore Summary: fun with printers Message-ID: <3292@ima.ima.isc.com> Date: 7 Feb 89 00:12:13 GMT References: <1000@taux01.UUCP> Reply-To: johnl@ima.UUCP (John R. Levine) Organization: Segue Software, Inc. Lines: 59 In article <1000@taux01.UUCP> taux01!cyosta@nsc.UUCP ( Yossie Silverman ) writes: >I have two stories to relate. Both have to do with IBM machines (the large >veriaty): > >1) Back when core memory was in use one could "listen" to the memory with a > transistor radio. ... Aw shucks, we did this with a PDP-8. The accumulator was displayed in fairly large incandescent bulbs on the front panel, which needed high powered drivers. Turning the bits on and off made plenty of radio noise. I've heard legends of PDP-9 programmers who would routinely leave a radio on the console as a debugging aid. >2) Printers produce a buzzing with varying frequency depending on the text > being printed (this is because of the rate at which the hammers strike the > slugs in the print chain). ... There was a legendary card deck that, when run through an old electromechanical accounting machine, would print out an American flag while playing the Star Spangled Banner. Speaking of printers, here are two silly stories from about 1969. At that time they used 360/20s as RJE terminals to the 360/91 mainframe. The '91 crashed all the time, so while waiting for the '91 to come back up we would toggle in little programs from the console, or labriously punch an up to 80 byte program on a card, then use the "load" button to read and start the program. There was constant competition for the most interesting single-card program. My best was an expensive mimeo machine that read in a deck of cards and listed it over and over. In one case, we experimented with the Universal Character Set buffer in the printer. The 1403 printer had interchangable print trains, but different trains would have different character layouts. The UCS buffer told what character was at what position on the train. When it printed a line, it would see what characters were at the right position, fire the appropriate hammers, move the train ahead one position, fire the appropriate hammers, and so on until the entire line was printed. So as an experiment, we filled the entire UCS buffer with the same character, then printed lines of that character. It printed about a page and a half real fast, then the cover opened about half way (it automatically opened whenever the printer ran out of paper, to warn the operator and dump ever-present coffee cups on the floor) and then blew a fuse. We cleared out. It hadn't occurred to us we could blow fuses with software. In another case, we experimented with the carriage control tape. Things like "skip to new page" or "vertical tab" were implemented with a loop of paper tape that had 66 rows, one for each line on a page, and 12 columns. You could do a skip to channel 1, and it would advance the paper and the tape until it found a hole in column 1. By convention, column 1 was top of page, column 2 top and middle of page, but you could program it any way you want. We tried various combinations and everything worked just fine until we tried a skip to channel 12. Unfortunately, there weren't any punches in column 12, so the paper just whizzed through the printer at full speed. We pushed the printer stop button. Nothing. We pushed the CPU stop button. Still nothing. Finally the CPU System Reset button stopped the printer. Being good ecologists, we fed the paper back into the feed box, then ran. -- John R. Levine, Segue Software, POB 349, Cambridge MA 02238, +1 617 492 3869 { bbn | spdcc | decvax | harvard | yale }!ima!johnl, Levine@YALE.something You're never too old to have a happy childhood.