SPEAKER(4) BSD Kernel Interfaces Manual SPEAKER(4)
speaker -- console speaker device driver
spkr0 at pcppi?
The speaker device driver allows applications to control the built-in
speaker on machines providing a PCPPI speaker interface.
Only one process may have this device open at any given time; open(2) and
close(2) are used to lock and relinquish it. An attempt to open() when
another process has the device locked will return -1 with an EBUSY error
indication. Writes to the device are interpreted as ``play strings'' in
a simple ASCII melody notation. An ioctl() for tone generation at arbi-
trary frequencies is also supported.
Sound-generation does not monopolize the processor; in fact, the driver
spends most of its time sleeping while the PC hardware is emitting tones.
Other processes may emit beeps while the driver is running.
Applications may call ioctl() on a speaker file descriptor to control the
speaker driver directly; definitions for the ioctl() interface are in
<dev/isa/spkrio.h>. The tone_t structure used in these calls has two
fields, specifying a frequency (in Hz) and a duration (in 1/100ths of a
second). A frequency of zero is interpreted as a rest.
At present there are two such ioctls. The SPKRTONE ioctl accepts a
pointer to a single tone structure as a third argument and plays it. The
SPKRTUNE ioctl accepts a pointer to the first of an array of tone struc-
tures and plays them in continuous sequence; this array must be termi-
nated by a final member with a zero duration.
The play-string language is modelled on the PLAY statement conventions of
IBM BASIC 2.0. The MB, MF and X primitives of PLAY are not useful in a
UNIX environment and are omitted. The ``octave-tracking'' feature is
There are 84 accessible notes numbered 1-83 in 7 octaves, each running
from C to B, numbered 0-6; the scale is equal-tempered A440 and octave 3
starts with middle C. By default, the play function emits half-second
notes with the last 1/16th second being ``rest time''.
Play strings are interpreted left to right as a series of play command
groups; letter case is ignored. Play command groups are as follows:
Letters A through G cause the corresponding note to be played in the
current octave. A note letter may optionally be followed by an
``accidental sign'', one of '#', '+', or '-'; the first two of these
cause it to be sharped one half-tone, the last causes it to be flat-
ted one half-tone. It may also be followed by a time value number
and by sustain dots (see below). Time values are interpreted as for
the L command below;.
If n is numeric, this sets the current octave. n may also be one of
'L' or 'N' to enable or disable octave-tracking (it is disabled by
default). When octave-tracking is on, interpretation of a pair of
letter notes will change octaves if necessary in order to make the
smallest possible jump between notes. Thus "olbc" will be played as
"olb>c", and "olcb" as "olc<b". Octave locking is disabled for one
letter note following by '>', '<', and 'O'.
> -- bump the current octave up one.
< -- drop the current octave down one.
Play note n, n being 1 to 84 or 0 for a rest of current time value.
May be followed by sustain dots.
Sets the current time value for notes. The default is L4, quarter
notes. The lowest possible value is 1; values up to 64 are
accepted. L1 sets whole notes, L2 sets half notes, L4 sets quarter
Pause (rest), with n interpreted as for L. May be followed by sus-
tain dots. May also be written '~'.
Sets the number of quarter notes per minute; default is 120. Musi-
cal names for common tempi are:
Description Tempo Beats per Minute
very slow Larghissimo 40-60
very slow Largo 40-60
very slow Larghetto 60-66
very slow Grave 60-66
very slow Lento 60-66
slow Adagio 66-76
slow Adagietto 66-76
medium Andante 76-108
medium Andantino 76-108
fast Moderato 108-120
fast Allegretto 108-120
fast Allegro 120-168
fast Vivace 120-168
fast Veloce 120-168
very fast Presto 168-208
very fast Prestissimo 168-208
Set articulation. MN (N for normal) is the default; the last 1/8th
of the note's value is rest time. You can set ML for legato (no
rest space) or MS (staccato) 1/4 rest space.
Notes (that is, CDEFGAB or N command character groups) may be followed by
sustain dots. Each dot causes the note's value to be lengthened by one-
half for each one. Thus, a note dotted once is held for 3/2 of its
undotted value; dotted twice, it is held 9/4, and three times would give
Whitespace in play strings is simply skipped and may be used to separate
Eric S. Raymond <firstname.lastname@example.org>, Feb 1990
Due to roundoff in the pitch tables and slop in the tone-generation and
timer hardware (neither of which was designed for precision), neither
pitch accuracy nor timings will be mathematically exact.
There is no volume control.
In play strings which are very long (longer than your system's physical
I/O blocks) note suffixes or numbers may occasionally be parsed incor-
rectly due to crossing a block boundary.
BSD April 29, 2017 BSD