Kevin Doyle
For those without the Music 4000 keyboard, this program is
designed to provide a simple musical keyboard on the BBC Micro and a means to
compose quickly and easily into AMPLE notation. If, like me, you know the sound
of the notes you want but find using the Staff Editor or typing in lines of
AMPLE notation a frustration of trial and error, then this program is for you.
The program takes key presses from the BBC keyboard and
plays notes on the currently selected voice(s) whilst displaying those notes
and their duration in AMPLE notation. This enables you to select an instrument and
play whatever you like without having to think about the staff or AMPLE
notation. Also, because the AMPLE notation is displayed as you play, you can
stop at any point and copy a phrase you like into an AMPLE word. This is
particularly useful when 'playing along' with an existing piece to find a
suitable accompaniment.
The program uses two rows of the BBC keyboard to represent
the available notes. These are arranged to mimic the layout of a musical
keyboard using the upper row for the 'black' notes, the lower for the 'white'.
Because the span of the BBC keyboard is fairly limited you can only play across
20 notes (an octave and two-thirds); but you can switch between any of the 11 available
octaves at the press of a key.
Because the note lengths in AMPLE are measured in very small
units, a facility is provided to round (or 'quantise') the note lengths played,
to the nearest multiple of any number from 1 to 999. This can be very useful in
composing multi-part pieces when the parts on each voice must keep time.
The program is quite
simple to use. It is in *EXEC format and should be read into your AMPLE program
using:
*EXEC U.AK
To hear the effect of your key presses you must have set up
a voice and instrument ready to play (e.g. by typing 1 VOICES 1 VOICE Upright SCORE).
You can check this before you start by typing some notes at the % prompt. Then
all you have to do is to enter 'AK' to start the program.
The first thing that happens is that the screen clears and
the AMPLEKEY display appears. The display is divided into three sections:
1) On the top two lines are the title and a line showing the
current note and the rounding number in effect.
2) The middle section is the area where the notes you play
appear in AMPLE notation - at the start it only shows the middle octave
indicator '0:'.
3) The bottom three lines show the relationship between the
keys on the BBC keyboard and the musical notes they represent. Sharps are shown
in green (the AMPLE notation also uses sharps).
If you press one of the keys indicated you will hear the
sound and see the note appear in the 'Current note' field. If it was a sharp
then the AMPLE notation '+' will appear in front. If you now press another note
you will see it replace the previous one in the 'Current note' field and the
previous note will appear next to the octave indicator with its length in AMPLE
notation. This will continue for each note you press. If you play notes more
than an octave apart the correct AMPLE notation (using '!') will be shown. To
play a rest, press the space bar.
To switch to another octave range on the keyboard press the
"<," or ">." keys. These move you down or up an octave
respectively. You should not press the SHIFT key - nearly all the keys in
AMPLEKEY only work when just the caps lock is on. The new octave will now be
displayed at the start of the next line.
If you type enough notes to fill the screen (something over
120), it will scroll up, a line at a time, to accommodate more. If you would
like to clear the screen and start again then press the TAB key. This again
displays the current octave at the start of the AMPLE display area.
To use the 'rounding' facility press the '?/' key. Once
pressed, the word 'Rounding' under the title starts to flash and the only
usable keys are the up and down cursor keys (to adjust the rounding number),
the SHIFT key (to increase the effect of the cursor keys by a factor of 10) and
the RETURN key (to 'fix' the rounding number and return to the keyboard). Once
a rounding number is established, the length of all future notes is adjusted up
or down to the nearest multiple of this number. Make sure you don't set the
number too high because note lengths of less than half the rounding number
become 0 and will not play if copied into a word.
Because note lengths in a tune will often be the same for
several notes in succession, the program will suppress the display of the note
length if this is the same as the last note. This is more likely with a
rounding number in effect.
To ensure a neat display, suitable for copying into an AMPLE
word, the program always displays the note length at the start of each line and
will not split the display of a note over two lines. You can start a new line
(with the current octave displayed) at any time by pressing the RETURN key.
If you type notes in very fast the program will not be able
to process these quickly enough and they will be stored in the keyboard buffer.
Because this means that the note lengths will not be exactly as you played
them, a warning is given by the 'Rounding' display near the top of the screen turning
red. Once the buffer is empty it will change back to its normal cyan colour.
The shortest note length that can be accurately recorded by the program is
about 12 hundredths of a second (i.e. a note length of 12 with the 'standard'
tempo of 48, 125=T).
The new octave, clear screen, new line and rounding keys
described above will stop the current note playing. The length of the note will
be measured to the point at which the new key was pressed.
To end "AK" and return to the % prompt, press the
ESCAPE key. This clears the information from the top and bottom of the screen,
but leaves all the displayed notes intact. Any note currently playing is
stopped. You will now be able to copy any of the displayed notation into an
AMPLE word. You can also see the equivalent staff notation by prefixing the
notation with %STAFF and calling the word into the Staff Editor.
The program ("U.AK") operates in MODE 7 and uses
about 1800 bytes of memory including the storage of its working variables. In
order to save memory the program has been packed into the smallest space
possible - it is not meant to be an illustration of good programming technique!
The version of AMPLEKEY provided is designed to be *EXECed
into existing pieces. If you wish to use AMPLEKEY when developing new pieces,
you should create a master program containing just AMPLEKEY. To do this, *EXEC AMPLEKEY
into a new program and then SAVE it. You can then LOAD this program when
starting a new piece of music and build the rest of your program around it.
Related file on this disc:
Published in AMPLINEX 005, May 1988
