romkey@kaos.UUCP (John Romkey) (03/29/88)
In article <25959@yale-celray.yale.UUCP> lisper-bjorn@CS.YALE.EDU (Bjorn Lisper) writes: >Some historic computer trivia: the Swedish late-fifties computer BESK at >some stage of its lifecycle had a loudspeaker connected to its instruction >register. Different instructions gave a different sound, so you could hear >it compute. A skilled operator could actually hear if the computer had got >stuck in an infinite loop! The Radio Shack TRS-80 Model 1 (a personal computer before PC meant IBM) put out enough RF interference that it became popular among TRS-80 hackers to put a small radio next to the machine to listen to what it was doing. Some people tried to program them to play music this way... -- - john romkey UUCP: ...harvard!spdcc!kaos!romkey ARPA: romkey@xx.lcs.mit.edu romkey@kaos.uucp Telephone: (617) 776-3121
davidc@umd5.umd.edu (David Conrad) (03/30/88)
From article <769@kaos.UUCP>, by romkey@kaos.UUCP (John Romkey): > In article <25959@yale-celray.yale.UUCP> lisper-bjorn@CS.YALE.EDU >>Some historic computer trivia: the Swedish late-fifties computer BESK at >> ... >>it compute. A skilled operator could actually hear if the computer had got >>stuck in an infinite loop! > The Radio Shack TRS-80 Model 1 (a personal computer before PC meant > IBM) put out enough RF interference that it became popular among > TRS-80 hackers to put a small radio next to the machine to listen to > what it was doing. Some people tried to program them to play music > this way... I read an article in some PC magazine (PC maybe) that described the correct frequencies to listen to your AT. The article claimed that it was fairly easy to hear an infinite loop. As an aside, netwatch, as distributed by IBM as part of their TCP/IP on the PC software has a noise option ('N') which makes a noise whenever a packet goes by. > - john romkey -drc
schwartz@gondor.cs.psu.edu (Scott Schwartz) (03/30/88)
In article <2516@umd5.umd.edu> davidc@umd5.umd.edu (David Conrad) writes: > [lots of quotations] >I read an article in some PC magazine (PC maybe) that described the correct >frequencies to listen to your AT. The article claimed that it was fairly >easy to hear an infinite loop. > >As an aside, netwatch, as distributed by IBM as part of their TCP/IP on the >PC software has a noise option ('N') which makes a noise whenever a packet >goes by. That's the spirit! But really, who needs special hardware to hear their machine think? If you sit quitely next to almost any computer, you can hear the high pitched noises that the circuit boards make as the load changes. Sitting next to my father's PC clone I find it easy to tell when it does some compute bound thing, like a bunch of floating point math (no coprocessor, by the way...). Or, sitting next to this Sun3, when X windows (slowly) repaints the screen the noise from the cpu is positively audible. Does OSHA (sp?) know about this? I mean, we should all be wearing protective earmuffs. :-) -- Scott Schwartz | Your array may be without head or schwartz@gondor.cs.psu.edu | tail, yet it will be proof against | defeat. -- Sun Tzu, "The Art of War"
radford@calgary.UUCP (Radford Neal) (03/31/88)
In article <769@kaos.UUCP>, romkey@kaos.UUCP (John Romkey) writes: > The Radio Shack TRS-80 Model 1 (a personal computer before PC meant > IBM) put out enough RF interference that it became popular among > TRS-80 hackers to put a small radio next to the machine to listen to > what it was doing. Some people tried to program them to play music > this way... I have a vague recollection back from when I was a first-year student (1974) of someone demonstrating a program for the PDP-8 that played a quite good rendition of some piece of music on a radio placed beside the CPU. In retrospect, this seems moderately unlikely, though not impossible. Does anyone know whether such a program existed? Whether it was feasible? I believe the machine had core memory, would that have helped? If it existed, it must have been some hack... I recall the music lasting at least 10 seconds, good enough to require 6K samples/second minimum, say 6 bits per sample, doesn't look like it fits in 4K 12-bit words... Maybe I was duped... Then again, the machine did have a disk... Radford Neal
dfk@duke.cs.duke.edu (David Kotz) (04/01/88)
In article <1503@vaxb.calgary.UUCP>, radford@calgary.UUCP (Radford Neal) writes: > I have a vague recollection back from when I was a first-year student > (1974) of someone demonstrating a program for the PDP-8 that played a quite > good rendition of some piece of music on a radio placed beside the > CPU. In retrospect, this seems moderately unlikely, though not impossible. > Does anyone know whether such a program existed? Whether it was feasible? Indeed it did exist; we ran it (c. 1980) on our PDP 8 in high school too (hmm, where did you go to school?). It was run in single-user mode, loaded in from a DECTAPE. It had a repertoire of 10-20 tunes some of which lasted a long time. They were quite good and even had several voices involved. Gotta love those old things with front panels, lights, and noises... David Kotz -- Department of Computer Science, Duke University, Durham, NC 27706 ARPA: dfk@cs.duke.edu CSNET: dfk@duke UUCP: {ihnp4!decvax}!duke!dfk
rwa@auvax.UUCP (Ross Alexander) (04/01/88)
In article <1503@vaxb.calgary.UUCP>, radford@calgary.UUCP (Radford Neal) writes: > I have a vague recollection back from when I was a first-year student > (1974) of someone demonstrating a program for the PDP-8 that played a quite > good rendition of some piece of music on a radio placed beside the > CPU. In retrospect, this seems moderately unlikely, though not impossible. and continues by observing that it would be difficult to fit enough information into a 4k pdp8 to allow more than 10 seconds of music, assuming 6k samples/second. True enough; but that's not how it's done ;-). The basic code is something like .=0010 MUSICP, MUSIC / autoincrement pointer to list of notes .=0200 / code lives on page 1 CLA / 0 --> accumulator PLAY, TLS / essentially, start a 1/10 second timer :-) TAD I MUSIC / get next note code TAD DELAYL / convert to index into delay list DCA DELAYP / save address of delay count PAUSE, TAD I DELAYP / refresh delay counter DCA STALL ISZ STALL / sleep for a while JMP .-1 TSF / has timer expired yet ? ****** JMP PAUSE / no, go stall some more JMP PLAY / yes, get next note STALL, 0 / sleep counter DELAYP, 0 / pointer into delay list DELAYL, DELAYS / constant to form above pointer DELAYS, 0100 / these values are clearly incorrect 0200 0300 . . . MUSIC=0400 / list of notes starts on page 2 END The reason this works (aside from coding errors; it's been _years_!) is that the TSF (marked with the asterisks above) induces a spike of RF energy as a side effect. If you sleep 1/4000 second, do a TSF, and loop back to the sleep, a radio will produce a 4 kilohertz tone. After 1/10 second, the TSF will skip over the JMP PAUSE and we will advance to the next note. This basic technique can be extended ( there is room for both a duration and a note code in each 12-bit word, for example ) get better encoding and also more than one voice; three voices is doable but tricky. You can also do a light show in the accumulator display while you're at it - this is really impressive. I sure wish we had an 8 in the machine room nowadays - it would add a nice traditional touch that's lacking (the vaxen are visually boring). Ross Alexander, Athabasca University alberta!auvax!rwa
fu@uicsrd.csrd.uiuc.edu (04/01/88)
I remember, when I was with ICL (in England) ~1980, listening to a ICL2960 playing "Land of Hope and Glory" to the Chairman, on one of his rare visits to the RnD site in Manchester, England. The Commissioning (debugging) Engineers claimed that a number of manufacturing diagnostics were designed to play specific tunes and that audio debugging was quite usual.
rober@weitek.UUCP (Don Rober) (04/01/88)
In article <1503@vaxb.calgary.UUCP> radford@calgary.UUCP (Radford Neal) writes: >I have a vague recollection back from when I was a first-year student >(1974) of someone demonstrating a program for the PDP-8 that played a quite >good rendition of some piece of music on a radio placed beside the >CPU. In retrospect, this seems moderately unlikely, though not impossible. We wrote some music using FOCAL on a PDP-8I (1971, 4K core memory, cheap AM transistor radio). It only lasted 2 or 3 seconds, but it did work. >.............. Then again, the machine did have a disk... ^^^^ Wow, we only had paper tape! -- ---------------------------------------------------------------------------- Don Rober UUCP: {pyramid, cae780}!weitek!rober Weitek Corporation 1060 East Arques Sunnyvale, CA 94086
jesup@pawl16.pawl.rpi.edu (Randell E. Jesup) (04/01/88)
In article <1503@vaxb.calgary.UUCP> radford@calgary.UUCP (Radford Neal) writes: >I have a vague recollection back from when I was a first-year student >(1974) of someone demonstrating a program for the PDP-8 that played a quite >good rendition of some piece of music on a radio placed beside the >CPU. In retrospect, this seems moderately unlikely, though not impossible. Who needs a radio?? The RPI X-Ray crystalography (sp) lab's PDP-8 serial #175 just ran the output of a Dec flip-chip pulse amplifier to a speaker on top of the cabinet. There were several large decks of music floating around for it. And I'm sure the RF would work too (it did on my TRS-80 Mod 1 - you also could watch it's screen on the TV next to it!) // Randell Jesup Lunge Software Development // Dedicated Amiga Programmer 13 Frear Ave, Troy, NY 12180 \\// beowulf!lunge!jesup@steinmetz.UUCP (518) 272-2942 \/ (uunet!steinmetz!beowulf!lunge!jesup) BIX: rjesup (-: The Few, The Proud, The Architects of the RPM40 40MIPS CMOS Micro :-)
die@frog.UUCP (Dave Emery) (04/02/88)
In article <1503@vaxb.calgary.UUCP> radford@calgary.UUCP (Radford Neal) writes: > >I have a vague recollection back from when I was a first-year student >(1974) of someone demonstrating a program for the PDP-8 that played a quite >good rendition of some piece of music on a radio placed beside the >CPU. In retrospect, this seems moderately unlikely, though not impossible. >Does anyone know whether such a program existed? Whether it was feasible? >I believe the machine had core memory, would that have helped? > > Radford Neal I remember such a program circulating around Genrad (where I then worked) in mid 1973. It played polyphonic Bach (? it has been years) that ran on for several minutes on an AM radio placed near a PDP-8e. I beleive it ran in 4 or 8K of (core) memory. It was loaded from paper tape and not that big. We disassembled it (we didn't have the source) and someone figured out how to enter our own music. I beleive it basically consisted of cleverly constructed nested counting loops, but that was 15 years ago and I do not recollect the details. I can confirm that such a program did exist however. ---- David I. Emery Charles River Data Systems 983 Concord St. Framingham, MA 01701 Tel: (617) 626-1102 uucp: ...!decvax!frog!die
davidsen@steinmetz.steinmetz.ge.com (William E. Davidsen Jr) (04/02/88)
In article <583@auvax.UUCP> rwa@auvax.UUCP (Ross Alexander) writes: | better encoding and also more than one voice; three voices is doable | but tricky. You can also do a light show in the accumulator display | while you're at it - this is really impressive. When I let people visit my office at home, they are not impressed by the MS-DOS machine with fancy graphics, nor the UNIX box with 2-4 remote user, they are blown away by my first (home) computer, a "war games" model IMSAI, with hundreds of blinking lights and switches (I have LEDs on the bankselected memory cards, too). -- bill davidsen (wedu@ge-crd.arpa) {uunet | philabs | seismo}!steinmetz!crdos1!davidsen "Stupidity, like virtue, is its own reward" -me
curry@nsc.nsc.com (Ray Curry) (04/02/88)
>I have a vague recollection back from when I was a first-year student >(1974) of someone demonstrating a program for the PDP-8 that played a quite >good rendition of some piece of music on a radio placed beside the >CPU. I'll tell you how old I am. When I started college, they were ripping out the vacuum tube IBM 7xx. The little computer (1620 I think) that was used to input programs to the IBM had a combination of core and relays that would produce audible sound without the external radio. Lots of programs existed around the lab that would produce a variety of music when run.
billc@prism.TMC.COM (04/02/88)
-> The Radio Shack TRS-80 Model 1 (a personal computer before PC meant
-> IBM) put out enough RF interference that it became popular among
-> TRS-80 hackers to put a small radio next to the machine to listen to
-> what it was doing. Some people tried to program them to play music
-> this way...
-
-I have a vague recollection back from when I was a first-year student
-(1974) of someone demonstrating a program for the PDP-8 that played a quite
-good rendition of some piece of music on a radio placed beside the
-CPU. In retrospect, this seems moderately unlikely, though not impossible.
-Does anyone know whether such a program existed? Whether it was feasible?
-I believe the machine had core memory, would that have helped?
-
-If it existed, it must have been some hack... I recall the music lasting
-at least 10 seconds, good enough to require 6K samples/second minimum, say
-6 bits per sample, doesn't look like it fits in 4K 12-bit words... Maybe
-I was duped... Then again, the machine did have a disk...
-
I don't doubt that someone programmed that. When I first got
into computers, there was a little kit computer called the
Altair 8800 (I think) that ran an 8080 processor (This was 1975
or so.) I heard the thing play "Daisy" through an ordinary AM
radio, by running a relatively short assembly language program.
I beleive that the way it worked is that some fairly standard
instruction gave out a strong RF pulse. The program consisted
of nested loops of proper lengths and some simple controls to
make the pulses come out as desired so that the radio could pick
it up.
Bill Callahan voice: 617-661-0777, ext. 149
Mirror Systems 2067 Massachusetts Avenue Cambridge, MA, 02140
billc@mirror.TMC.COM
UUCP : {mit-eddie, pyramid, wjh12, cca, datacube}!mirror!billckolding@ji.Berkeley.EDU (Eric Koldinger) (04/02/88)
In article <1503@vaxb.calgary.UUCP> radford@calgary.UUCP (Radford Neal) writes: > >I have a vague recollection back from when I was a first-year student >(1974) of someone demonstrating a program for the PDP-8 that played a quite >good rendition of some piece of music on a radio placed beside the >CPU. In retrospect, this seems moderately unlikely, though not impossible. >Does anyone know whether such a program existed? Whether it was feasible? >I believe the machine had core memory, would that have helped? I definitely heard a machine play music on a radio once. It was an IBM machine, probably a S/370 of some sort (Ok, so I'm not even sure it was IBM, but it was blue). It was back in the mid- to late-70's. I was given a tour of a computer center, got to type my name on a punch card and get it printed out, and got to hear a computer broadcast a piece of classical music. Wish I could remember the piece......... _ /| Eric \`o_O' kolding@ji.berkeley.edu ( ) "Gag Ack Barf" {....}!ucbvax!ji!kolding U
farren@gethen.UUCP (Michael J. Farren) (04/03/88)
In article <5029@nsc.nsc.com> curry@nsc.UUCP (Ray Curry) writes: >I'll tell you how old I am. When I started college, they were ripping out the >vacuum tube IBM 7xx. The little computer (1620 I think) that was used to input >programs to the IBM had a combination of core and relays that would produce >audible sound without the external radio. Lots of programs existed around the >lab that would produce a variety of music when run. My three fave computer noise stories: I. The line printers used with some earlier IBM systems had (as many still do) bands of type which continuously rotated, with hammers that were fired when the appropriate letter came by. By selecting the output carefully, you could get the hammers to fire at a fixed frequency, and by varying the output you could change this frequency. The story goes that someone programmed the thing to play the Star Spangled Banner, with the added fillip that on the "Rockets' Red Glare" passage, all of the doors to the automatic tape drives would flip open. II. Processor Technology's SOL computer had a Star Trek game which, if you put an AM radio next to the CPU, would generate the appropriate sound effects for the game - phasers firing, klaxons wailing, etc. III. A computer used in the navigation center for a Polaris sub, with an amplifier/speaker connected to the high order bit of its accumulator and appropriate software for generating tones, won the ship's talent contest for its rendition of "Raindrops Keep Falling On My Head". Number one may be apocryphal, but sounds reasonable. Numbers two and three are definitely real. -- Michael J. Farren | "INVESTIGATE your point of view, don't just {ucbvax, uunet, hoptoad}! | dogmatize it! Reflect on it and re-evaluate unisoft!gethen!farren | it. You may want to change your mind someday." gethen!farren@lll-winken.llnl.gov ----- Tom Reingold, from alt.flame
neighorn@qiclab.UUCP (Steve Neighorn) (04/03/88)
In article <769@kaos.UUCP> romkey@kaos.UUCP (John Romkey) writes: >The Radio Shack TRS-80 Model 1 (a personal computer before PC meant >IBM) put out enough RF interference that it became popular among >TRS-80 hackers to put a small radio next to the machine to listen to >what it was doing. Some people tried to program them to play music >this way... >-- > - john romkey Indeed, the Radio Shack Model 1 (bless that little old Z80) became a popular alternative to commercial radio (and no wonder these days!) through the use of custom jukebox programs. Several people got together and wrote out a complete translation table that could be used to derive musical notes from the Model 1's built-in BASIC statements. It was then relatively easy to 'program' sheet music on the machine. We were all quite proud of ourselves until we discovered some other locals had done the same thing with their pdp-11's... And to add insult to injury, their computer music was in 3-part harmony! -- Steven C. Neighorn !tektronix!{psu-cs,reed,ogcvax}!qiclab!neighorn Portland Public Schools "Where we train young Star Fighters to defend the (503) 249-2000 ext 337 frontier against Xur and the Ko-dan Armada"
littauer@amdahl.uts.amdahl.com (Tom Littauer) (04/04/88)
In article <850@gethen.UUCP> farren@gethen.UUCP (Michael J. Farren) writes: > >My three fave computer noise stories: > >I. The line printers used with some earlier IBM systems had (as many > still do) bands of type which continuously rotated, with hammers that > were fired when the appropriate letter came by. By selecting the output > carefully, you could get the hammers to fire at a fixed frequency, and > by varying the output you could change this frequency. The story goes > that someone programmed the thing to play the Star Spangled Banner, > with the added fillip that on the "Rockets' Red Glare" passage, all of > the doors to the automatic tape drives would flip open. > > ... deleted for brevity ... > >Number one may be apocryphal, but sounds reasonable. Back in days of yore, I had a copy of a preogram which would do the above trick (minus the tape door geewhiz) for an arbitrary melody. Same for the radio trick. Just goes to show that there've been personal computers for years (at least after midnight...) -- UUCP: littauer@amdahl.amdahl.com or: {sun,decwrl,hplabs,pyramid,ihnp4,ames,uunet,cbosgd}!amdahl!littauer DDD: (408) 737-5056 USPS: Amdahl Corp. M/S 330, 1250 E. Arques Av, Sunnyvale, CA 94086 I'll tell you when I'm giving you the party line. The rest of the time it's my very own ravings (accept no substitutes).
lisper-bjorn@CS.YALE.EDU (Bjorn Lisper) (04/04/88)
In article <850@gethen.UUCP> farren@gethen.UUCP (Michael J. Farren) writes: .... >My three fave computer noise stories: > >I. The line printers used with some earlier IBM systems had (as many > still do) bands of type which continuously rotated, with hammers that > were fired when the appropriate letter came by. By selecting the output > carefully, you could get the hammers to fire at a fixed frequency, and > by varying the output you could change this frequency. The story goes > that someone programmed the thing to play the Star Spangled Banner, > with the added fillip that on the "Rockets' Red Glare" passage, all of > the doors to the automatic tape drives would flip open. [II, III deleted] >Number one may be apocryphal, but sounds reasonable. Numbers two and >three are definitely real. I believe in it. When I became an undergrad in Stockholm in 1975 somebody at the physics lab told me that they had a program on some machine that could play music on a line printer by printing the proper characters at the right time. (I think the melody was "Gotlandsk sommarnatt", by the way.) I never heard it perform myself, though, so I can't guarantee the correctness of this story. This kind of art is definitely becoming extinct with the introduction of laser printers.... Bjorn Lisper
mrspock@hubcap.UUCP (Steve Benz) (04/05/88)
In article <1503@vaxb.calgary.UUCP> radford@calgary.UUCP (Radford Neal) writes: >I have a vague recollection back from when I was a first-year student >(1974) of someone demonstrating a program for the PDP-8 that played a quite >good rendition of some piece of music on a radio placed beside the >CPU. In retrospect, this seems moderately unlikely, though not impossible. Actually, you don't even need anything as high-tech as a PDP-8 to do this stunt. As I remember, there was an article for the Timex-Sinclair 1000, or potentially one of the earlier names for it, which could play actual notes on AM radio by putting the two wires of the antenna underneath the machine. You could produce different notes by putting the machine into infinite loops at various points in memory, i.e: ORG X Y BRA Y The frequency of the note was proportional to X. Steve
kds@naucse.UUCP (Kevin Strietzel) (04/05/88)
In article <850@gethen.UUCP>, farren@gethen.UUCP (Michael J. Farren) writes: >In article <5029@nsc.nsc.com> curry@nsc.UUCP (Ray Curry) writes: >>I'll tell you how old I am. When I started college, they were ripping out the >>vacuum tube IBM 7xx. >My three fave computer noise stories: >I. The line printers used with some earlier IBM systems had (as many >still do) bands of type which continuously rotated, with hammers that >were fired when the appropriate letter came by. By selecting the output >carefully, you could get the hammers to fire at a fixed frequency, and >by varying the output you could change this frequency. I think this was done. I remember hearing about it a *long* time ago from a reliable source. Knowing him, he'd probably tried it. More recently I tried this on an old Oki 82 matrix printer. It wasn't very successful, but got some interesting results. It was hard to find particular characters that fired the print wires at the right frequency! And yes, chain, train and band printers are still made by lots of companies. The fastest I remember hearing about is 2200 lines/minute. -- +------------------------------------------------------------------------------+ | Kevin (So What If I'm Just a Student) Strietzel | | {... | allegra | ihnp4 | ...}!arizona!naucse!kds | | "It's easy to pass the buck - especially to someone who wants it!" -- me |
chuckh@apex.UUCP (Chuck Huffington) (04/06/88)
In article <850@gethen.UUCP>, farren@gethen.UUCP (Michael J. Farren) writes: > In article <5029@nsc.nsc.com> curry@nsc.UUCP (Ray Curry) writes: > >I'll tell you how old I am. When I started college, they were ripping out the > >vacuum tube IBM 7xx. The little computer (1620 I think) that was used to input > >programs to the IBM had a combination of core and relays that would produce > gethen!farren@lll-winken.llnl.gov ----- Tom Reingold, from alt.flame The tape drives used with IBM 70x machines as well as the later drives for the 709x systems used a pair of prolay's to control tape motion. They were an electromechanical device that pushed the tape against a rotating capstan or a fixed capstan to stop. They were very noisy. There was a program that intitiated tape ops and aborted them at appropriate rates to produce music. It worked but it tended to wear out tape and if run too long, knocked the drives out of adjustment. The story about music from line printers is also true. Chuck Huffington Apex Computer Company
davidsen@steinmetz.steinmetz.ge.com (William E. Davidsen Jr) (04/06/88)
My first attempt to make music on a printer was not very sucessful,
although I did find out that (a) if I fired all of the hammers on the
line at once it made a GREAT noise, (b) that if I did it three times
quickly the capacitors on the P/S would discharge blowing the P/S fuse
try to recharge, and (c) the fuse is in a BITCH of a position.
Also from the mid 60's:
We had Potter "mil spec" tape drives, so called because they could be
serviced from the front and set flush on a wall. These had weak door
latches and bad mub mounting systems. If a full length tape was rewound,
and the hub brakes were tight, the door and the hub would both release.
One of our operators noticed this about to happen while visitors were
in the computer room, and stood by the drive, caught the tape as it flew
off, pulled the ring, put on the strap, and walked away. This was before
self loading (much unloading) tapes. Another time it happened with a
lesser operator on duty, and the reel hit the floor at many rpm and
rolled the length of the room. Fortunately the tape is being wound on
and didn't get spilled.
Our GE 4020 (industrial control system) has an optical paper tape
reader. It was very fast, and the operators had a great deal of trouble
with the tapes breaking. They got into the habit of stringing the tape
in a 30 foot "fan fold" on the floor before starting the reader. The
tape landed about 8-10 feet away on the other side.
Some people wanted to use mylar tape, but the operators were very
careful when this was done. A mylar ribbon at ten feet/sec is a very
good meat saw.
--
bill davidsen (wedu@ge-crd.arpa)
{uunet | philabs | seismo}!steinmetz!crdos1!davidsen
"Stupidity, like virtue, is its own reward" -memef@aplvax.jhuapl.edu (Martin E. Fraeman) (04/06/88)
A good friend of mine (John Spies) who went to Northwestern worked on a
PDP-8I his freshman year (1969-70). He used the IOT instruction
to generate RF. The IOT would cause the I/O bus drivers to
pulldown causing a large current pulse that dominated the stray
RF the machine was putting out. By varying the frequency of IOT
instructions music would be picked up by an AM radio near the
machine. The IOT loops were timed by counting instructions which
was easy on the early 8's because they weren't microcoded (RISC
strikes again -). John eventually extended things to the point where it
would do 4 simultaneous voices. Since he just stored note values and
durations that were interpreted on the fly, a substantial amount of
music (an entire Bach 3 part invention) could be held in the PDP-8
4kw of memory. I believe John also eventually wrote a graphical
music editor to translate traditional notation into those tables.
Pretty astounding what some good assembly language programming
and a shoehorn can do on a clever machine.
Marty Fraeman
US Mail: Johns Hopkins University Applied Physics Laboratory
Johns Hopkins Road
Laurel, Md. 20707
301-953-5000 x8360
Usenet: {...allegra,seismo}!umcp-cs!aplcen!mef
Arpanet: mef@aplvax.jhuapl.edukirchner@uklirb (04/12/88)
Hello,
I can't keep quiet when all others make noise-:)
During my time at Karlsruhe University ( appr. 1972 ) i got in touch with
machines from Zuse ( the one who invented , or at least built , the
first computer ), namely a Z22 and a Z23.
On these machines main memory was a drum, rotating at 6000 rpm. The console
had light for all bits in the accu, the instruction register etc.
There was also a loudspeaker which made a pulse for each memory request.
So by listening and looking we could easily see if our programs were
in endless loops, we knew when compilations ( ALGOL60 !! ) were near
to end at specific sounds and blink sequences etc.
It was also possible to play music by writing programs which jumped
in carefull calculated sequences around the drum. I still have papertapes
with christmas songs -:)
BTW: The machine is now in our cellar, perhaps we get time and space sometimes
to build a little museum. There are other nice things too in our store.
Just to correct: the z23 was NOT the university computer of that time,
we just had fun in using it until it was dismantled. At that time the
computing center had a UNIVAC 1108 with 3 processors and we were happy
with it.
Reinhard Kirchner
University of Kaiserslautern
Computer Science
P.O.Box 3049
D-6750 Kaiserslautern
W-Germany
Arpa: kirchner@uklirb@unido
or: kirchner%uklirb.uucp%germany.csnet@RELAY.CS.NET
CSNET: kirchner%uklirb%uka.csnet@csnet-relay.arpa
UUCP: ..{mcvax!}unido!uklirb!kirchnerbobw@wdl1.UUCP (Robert Lee Wilson Jr.) (04/15/88)
I guess my age shows when I am surprised that playing music on a computer is thought to be surprising! In addition to the radios which I thought we all had used (most effective on core machines: the fast, high current pulses could be accurately timed) the early CDC machines had a built in console speaker. Current proportional to the upper octal digit of the accumulator was sent through the voice coil, and there was a volume control. In normal system operation you got some idea of the kind of stuff going on: If there was a long steady tone or no noise at all (i.e. the A register was not changing) you assumed the machine was in a small tight loop, and the system operator would take that as his cue to interrupt the program. (Of course that was batch mode, and if your program did not get interrupted it could wipe out your whole budget due to a programming error!) Som of the diagnostics made use of the noises, or at least the engineers new what noises to expect at certain times: The tape drive diagnostic for the CDC 1604 was named Bagpipe, and sounded like one in rhythm with the tapes sawing back and forth. By intentionally juggling the A register you could program music or other sounds. I had programs which composed music by the rules of florid counterpoint, and whose output I have still heard only on the console speaker. I had a quick console thumb-in which would let you make race-car sounds, including braking and gear shifting, by pushing the buttons under the A register display. At the Univ of Wisconsin we kept a paper tape handy to play "On Wisconsin" for visiting dignitaries. There was a rumor that CDC 3600's were shipped out with "Oklahoma" for full chorus and orchestra in (non-volatile) core, but since I can't imagine one coming up and running without something trashing memory I don't know if anyone was able to test it! Regards, Bob Wilson (I don't even remember such opinions, much less attribute them to my employer.)