From: tmoravan@netcom.com (Tom Moravansky)



OSCar Software Revs.
--------------------

Versions 3 and 5
----------------
  Version 3 was the earliest ever supplied (up to November 83) and subsequent
units up to April 84 have contained version 5.  Version 4 was never supplied.

  The main difference between these versions is the action of the TRIGGERING
and FUNCTION rotary switches.  With version 3, the effective positions of these
switches are always set when a voice is selected.  This has the disadvantages
that when any of the pre-set voices are selected, envelope repeat, arpeggiator
or duo functions are immediately cancelled and have to be selected again if
they are requiredd.

  Version 5 makes these switches respond to voice selection only when they are
physically in certain positions:- SG (single triggering) or MULT (multiple
triggering) in the case of the TRIGGERING switch and NORM (normal) in the
case of the FUNCTION switch.  In any other positions, the actual physical
position of the switch concerned over-rides.  If a voice is stored, the
effective positions of these switches are still stored (as with version 3) and
will be recalled when that voice is later selected, as long as the switches
are set in the programmable positions mentioned above.


Version 6
---------
  Fitted in units manufactured after April 84.

WAVEFORM BUILDING

  HARMONIC LEVELS.  In earlier versions, the amount of each harmonic that is 
added into the waveform for each harmonic "insert" depends on which harmonic
it is - the fundamental is at full level, the second harmonic is at half the
fundamental level, the third is at one third of the fundamental level, etc.
as described on page 9.2 in the manual.  The disadvantage of this arrangement
is that it takes a long time to build a waveform with a high "top end"
content.  Furthermore, if the lower harmonics and the fundamental are present,
they always have to be at fairly high levels thus limiting the range of sounds
possible.

  With version 6, the fundamental and all harmonics add into the waveform at
the same level.  Each one can be entered up to 16 times.  As with earlier
versions, the waveform is automatically scaled to full size each time it is
calculated so that inserting or deleting harmonics only change their RELATIVE
size with respect to the whole waveform.  This is fine for certain sounds but
it restricts the waveforms to only 24 harmonics.  To enhance the range of
sounds possible, version 6 only scales the waveform up to a certain amount of
harmonic entries.  Beyond this amount, continued harmonic entries cause the
equivalent of amplifier "clipping", thus introducing harmonics higher than the
24th.  Although these higher harmonics can only be controlled in a fairly
crude way, their overall effect can be increased gradually by sinply adding in
more and more harmonic entries to the waveform until the desired sound is
obtained.

  SPEED OF WAVEFORM CALCULATION.  The time taken to calculate these built-up
waveforms, either in the waveform edit mode or when just selecting one of the
programmable waveforms, can obviously be a nuisance.  The calculation time
has been greatly reduced in version 6; if both oscillators are being used on
the same waveform, it takes about a quarter of the time taken in earlier
versions.  It may have been noticed that changing the octave register between
the top three settings causes a delay during which the waveform is recalculated;
this delay does not occur with version 6.

PRE-SET WAVEFORMS

  The pre-set waveform obtained from key "-7" has been changed to a "random"
waveform which contains very high levels of high harmonics.  It is most
effective in the lower octave registers where these higher harmonics are in
the audio band.

  Somce of the other pre-set waveforms have been changed slightly but it may
not be noticed.  Notice that the pre-set waveforms do not cause a delay for
calculation and are therefore more suitable than the programmable waveforms
for including in voices selected during CHAIN playback.

EXTERNAL TRIGGER SIGNALS

  In earlier versions, trigger OUT - the ring connection of the jack socket - 
produces a +5 volt pulse every time the volume envelope generator is triggered.
In version 6, this is still true except during sequence playback when a pulse
occurs on every sequence beat.  This provides a clock for synchronising other
instruments if required.

  The function of External trigger IN - the tip connection of the jack socket
(which would normally be the one used for synchronising) - is basically
unchanged in version 6 except that it now responds much faster than with
earlier versions.

CASSETTE SAVE AND LOAD

  During loading with earlier versions, a poor tape signal can lead to a
lock-up situation or to loading of incorrect data with no error indication.
With version 6, if a bad tape signal is receivedd, the system will either show
an error (in the normal way) and carry on if synchronisation has not been lost,
or it will abandon the loading of that type of data (waveforms, voices or
sequences) and leave the appropriate indicator ON, ready for another attempt
to load that type of data.

  There are also some minor differences in the LED display during saving and
loading but they are not important.


Version 7
---------
  Fitted in units manufacturered after May 84.

VOICE EDITING

  With earlier versions after a voice has been selected, turning any of the
continuously variable controls causes the "edit find display".  To obtain
manual control of each parameter, it is necessary to find the active position
of the control using the display as a guide.

  Version 7 provides a simpler editing scheme in which it is only necessary to
turn each knob slightly to obtain manual control.  Now, editing is much quicker
and it is not necessary to look at the octave display.  The position finding
display is still available if required.  To find the position, hold down the
STORE button while turning the knob and the find display will operate.

  The FILTER DRIVE setting works in the reverse way (ie the display operates
if the STORE button is NOT held down) so that the knob can normally act as the
volume control without disturbing the filter drive setting.

VOICE SELECTION ON POWER-UP

  Version 7 selects voice 1 on power-up.  Earlier versions select "panel" on
power-up.


Version M1 (MIDI)
-----------------
  First MIDI version, introduced in September 84, with all the features of
version 7 plus all 36 voices become user-programmable and sequence space is
increased to over 1500 events.  

  The MIDI implementation covers the 3 octave range of the keyboard.


Version M1A (MIDI)
------------------
  Fitted after November 84.

  MIDI note receive response much faster than version M1.

  Timing clock receive implemented.


Version M2 (MIDI)
-----------------
  Fitted after February 85.

EXTENDED NOTE RANGE

  MIDI note receive response extended to cover from G - over 2 octaves below
key "0" to F - over 2 octaves above key "0" (59 notes total).  Note that it
is not possible to transfer sequence data between version M2 and earlier
versions.

START AND STOP RECOGNITION

  MIDI Start and Stop receive implemented:-

  The Start message enables Timing Clock receive
  The Stop message disables Timing Clock receive and resets the current
sequence to the beginning.

  Timing Clock receive can also be enabled and disabled manually using the
SPACE button with key "20".

  The addition of Start and Stop response allows synchronised sequence starts
with systems which leave the Timing Clock running permanently.  The sequence
reset after the Stop message allows repeated sequence starts without touching
any OSCar controls.  Note that it is still necessary to press the sequence
start button in the first place - twice if repeated playback is required.

TAPE VERIFY FUNCTION

  A verify function has been added to allow checking of cassette data without
losing the data in memory.

  Follow the normal procedure for loading from a cassette to the OSCar but just
before starting the recorder, press the "cancel" (DELETE) button.  The BEAT LED
will light to show that no data will be loaded into the OSCar memory.  However,
the OCTAVE display will still show loading status and any read errors in the
usual way.

  It is not possible to cancel the verify mode during a load session.  If all
the selected data types are received, the session will terminate automatically
as usual.  If they have not all been received, the escape function can be used
(press "ready" and "cancel").






