Here can be found the most wonderful music created on the computers
DATASAAB D2, D21 and D22. The material is recorded from an EP released
to the memory of the D21 and D22 at Kraftdata and recorded in 1967 (D21) and 1970 (D22).
Software for playing of these files under DOS, Windows, OS/2, Mac, Amiga, BeOS and a number of unix flavors can be found here.
A note on the quality:
Pieces marked by * are of significantly better quality than the rest. The reason for this is that these have been re-sampled using a lot better equipment. The other's files were regretably lost due to unfortunate circumstances after the re-sampling, but I hope to get the opportunity to re-sample those as well within a near future.
COMPUTER MUSIC created on the DATASAAB D21 and D22 computers
Since the functions in a computer is controlled by an exact
quarts-crystal clock, it's easy to construct program frequences to be
executed with a determined time base. The D20 computers works
according to the binary system with ones and zeroes represented by
electrical pulses. By connecting an amplifier and loudspeaker to a
specific numberposition in the machine these impulses can be made
audiable. From school physics we remeber the connection between
frequency and time as f = 1/t. To get the tone middle a with the
frequency 440 Hz you feed the amplifier with impulses with an interval
of approximately 0,00227 seconds. In the same manner the other tones's
intervals are calculated. It's easy as long as you play with only one
part and it's not possible to play more than one tone at the same
time. One way to get around the problem is to repeatedly play the diffrent tones
in a chord individually. The echo of the tape will make the ear hear
it as the tones were sounding at the same time.
A better way to accomplish polyphonic sound is to use a so called
digital to analogue converter or just dac. It's an output-device which translates
the computers representation of numbers to an electrical current
corresponding to the number sent. Normally the dac were used to
control for example a plotter. With the tonalstring with the dac you have full
control over the tonal curve and can add many tones amplitudes before
D21 in memoriam
The D2 heritage (0:30/mono/236K)
The D2 was the first transistor based computer at SAAB, developed in
the late 50's. It had limited memory why the time base for the
different tones was fetched from the paper tape reader with the side
effect of it beating the time.
Christmas Songs (1:07/mono/524K)
An attempt top play many tones at the same time by quickly switch
between the different tones in a chord.
Mozart: ''Ein musikalisches Würfelspiel'' [A Musical Game
of Dice] (1:39/mono/628K)
A system for the composing of waltzes developed by Wolfgang Amadeus Mozart
as diversion. He compiled a set of notes with numbered
bars. There were also a table and two dice. After every roll you
checked the table for the bar to be played. The sound of the waltz was
completely random. The rolls of dice are randomized by the computer.
Mozart: Würfelspiel, the second try (2:13/mono/912K)
Now with a tonal string over a digital to analogue converter.
D22 in memoriam
One can imagine an organ with the pipes for the difrerent tones placed
from left to right.
Mozart: Würfelspiel, the third try (4:58/stereo/4106K)
Here with a digital to analogue converted tonal string where the
curves for the different organ voices are calculated by adding the sine
waves which make upp the key notes and overtones.
Register possibilities, voices and the partial tones relative amplitude
The waltzes are played quadrophonic in stereo and the timbre is
changed after every recapitulation.
J.S. Bach: ''Bist du bei mir'' from Notenbüchein Anna
Magdalena Bach (0:49/stereo/672K)
Funeral music to the end of the D20 era.
Most of the text on this page is taken from the record's cover and
then translated into English.
* By calculation (3:10/stereo/2970K)
The composition performed by a computer was made for the opening of SPADAB's central in Malmö 18 April 1967.
Göran Sundqvist, producer, arranger and programmer of this music.
Göran began working with computers at the SAAB electronics department
in the end of the 50's, where he took part in the development of the
D2 and later the D21.
In 1962 he went to Skandinaviska Elverk in connection with the first
1979 Skandinaviska Elverk's computer department was transformed into
Kraftdata where Göran worked until 1993.
A big thanks to Göran Sundqvist for his work with the programming and recording and for his permission of using the music here.
Many thanks also to Göran Sedvall at the department of computer science at
Linköping University for the recording of this record
on which these files are based. The original can be seen in a showcase at the
Datasaab exhibition in the hallway which connects the B and E buildings at Linköping Institute of Technology.
Thanks also to Daniel Högkvist and Linköping's student radio for the re-sampling.
Last modified: Mon May 24 21:45:32 MET DST 1999