SOUND
SOUND is a BASIC command to make sounds.
| Availability | Present in all original versions of BBC BASIC. | |
| Syntax | SOUND <numeric>,<numeric>,<numeric>,<numeric>
| |
| Token (hex) | D4 (command)
| |
| Description | Generates sounds. | |
Contents
Description
SOUND calls OSWORD &07 to generate sounds. It is most
commonly used to generate sounds with the internal sound generator, but it
can also be used to create speech or MIDI sounds, as specified by the
channel parameter.
Defined channel numbers
| &0xxx | Sound generator |
| &1xxx | Sound generator |
| &20xx | Watford Electronics Speech system[1] |
| &FExx | MIDI control [2] |
| &FFxx | Speech system [3] |
Implementation
Internal sound system
SOUND &0xxx,volume,pitch,duration
SOUND &1xxx,volume,pitch,duration
The channel number encodes &HSFC where:
- H: Hold 0 or 1
- S: Sync 0 to 15, 0 to 3 usually implemented
- F: Flush 0 or non-0 (usually 0 or 1)
- C: Channel 0 to 15, 0 to 3 usually implemented
The internal sound system implements 4 channels (1 on the Electron), but extensions can increase the number of supported channels. For example, the Electron Sound Expansion supports four channels, and MIDI redirection can support 16 channels treating each channel as a polyphonic note. Channel 0 is conventionally a 'noise' channel.
The volume, pitch and duration are 8-bit numbers with bit 8 and higher ignored.
Watford Speech
SOUND &20xx,word,library,0
Watford speach commands can be sent with SOUND &2000, which is usually coded as SOUND 8192.
Bit 0-7 of the channel number is ignored.
MIDI control
SOUND &FExx,command,note,velocity
MIDI commands can be sent with SOUND &FEFF and SOUND &FEFE which are usually coded as SOUND -257 and SOUND -258.
- SOUND -257,Command,Note,Velocity - Send to current channel (channel=&FEFF)
- SOUND -258,Command,Note,Velocity - Send raw MIDI command (channel=&FEFE)
- SOUND -257 or -258,Control<0,num,num - MIDI system control
If Command is &0000-&007F it is a MIDI data byte and sent stright to the MIDI system unchanged. This allows extended sequences to be sent, such as MIDI System Exclusives.
If Command is &0080-&00FF it is a MIDI command byte. Command bytes &80-&EF are channel-specific commands. SOUND -258 uses them as supplied, SOUND -257 sends them to the current MIDI channel by adding the current channel to the bottom nybble. So, if the current MIDI channel is 4, SOUND -257,&80... will send to MIDI channel 4, and SOUND -257,&8F should send to MIDI channel 3. Some implementations do not correctly round the channel number within the nybble in the second example.
Note and Velocity are 7-bit numbers with bit 7 and higher ignored, other than MIDI command &Ex which can specify a 14-bit Note number.
Speech system
SOUND &FFxx,command,0,0
The channel number indicates what to do with the command, the command is an 8-bit number with bit 8 and higher ignored.
- SOUND &FFFx,number,0,0 - speak from PHROM 15-x with word number. From a coding view this is usually written as SOUND -1,n,0,0 to SOUND -16,n,0,0.
- SOUND &FFBx,address,0,0 - speak from PHROM 15-x from the absolute address.
- SOUND &FF60,command,0,0 - start sending speech using phoneme 'command.
- SOUND &FF00,command,0,0 - continue sending speech using phoneme 'command.
SOUND &FF01-&FF7F actually send the bottom byte as the Speech command to use.
Summary
SOUND Channels
--------------
%000H SSSS FFFF CCCC Internal sound system
%0010 0000 xxxx xxxx Watford Electronics Speech
%1111 1110 1111 111x MIDI control
%1111 1111 xxxx xxxx Speech
Sound system
------------
SOUND %000hssss:xxxfcccc, %xxxxxxxx:xxxvvvvv, %xxxxxxxx:pppppppp, %xxxxxxxx:dddddddd - Make sound
Watford Speech
--------------
SOUND %00100000:xxxxxxxx, %xxxxxxxx:wwwwwwww, %xxxxxxxx:llllllll, %xxxxxxxx:xxxxxxxx - Speak word
MIDI
----
(note: some of this is wrong)
SOUND %11111110:xxxxcccc, %0xxxxxxx:0ddddddd, %xxxxxxxx:xxxxxxxx, %xxxxxxxx:xxxxxxxx - MIDI data
SOUND %11111110:xxxxcccc, %0xxxxxxx:10dddddd, %xxxxxxxx:xnnnnnnn, %xxxxxxxx:xvvvvvvv - MIDI note
SOUND %11111110:xxxxcccc, %0xxxxxxx:110ddddd, %xxxxxxxx:xnnnnnnn, %xxxxxxxx:xxxxxxxx - MIDI change
SOUND %11111110:xxxxcccc, %0xxxxxxx:1110dddd, %xxvvvvvv:vvvvvvvv, %xxxxxxxx:x0000000 - MIDI bend
SOUND %11111110:xxxxcccc, %0xxxxxxx:1110dddd, %xx000000:0vvvvvvv, %xxxxxxxx:xvvvvvvv - MIDI bend
SOUND %11111110:xxxxcccc, %0xxxxxxx:1111dddd, %xxxxxxxx:xxxxxxxx, %xxxxxxxx:xxxxxxxx - MIDI system
SOUND %11111110:1111111c, %1xxxxxxx:1111dddd, %xxxxxxxx:nnnnnnnn, %xxxxxxxx:xxxxxxxx - MIDI control
\--\/--/
MIDI command if b15=0 and b7=0
Speech
------
SOUND %11111111:11xxrrrr, %xxxaaaaa:aaaaaaaa, %xxxxxxxx:xxxxxxxx, %xxxxxxxx:xxxxxxxx - Speak word
SOUND %11111111:10xxrrrr, %xxaaaaaa:aaaaaaaa, %xxxxxxxx:xxxxxxxx, %xxxxxxxx:xxxxxxxx - Speak from address
SOUND %11111111:0cccxxxx, %dddddddd:dddddddd, %xxxxxxxx:xxxxxxxx, %xxxxxxxx:xxxxxxxx - Speak data word
SOUND %11111111:00000000, %dddddddd:dddddddd, %xxxxxxxx:xxxxxxxx, %xxxxxxxx:xxxxxxxx - Speak data word
\--\/--/
if b7=0, if<>0, sent to Speech as command, normally use &FF60 for Speak External
Trivia
In the original development of BBC BASIC, the sound command was BEEP which can be seen from the token position for SOUND, alphabetically with other keywords starting with 'B'[4]:
Originally: Became: D4: BEEP D4: SOUND D5: BPUT D5: BPUT D6: CALL D6: CALL D7: CHAIN D7: CHAIN etc.
References
Jgharston 00:30, 2 January 2008 (UTC)
