|the fx-602p released around 1982 is thought by
many as the finest calculator casio ever made. An evolution
of the fx-502p with more memory and
an alpha-numeric display. it was the last of the casio step
programmables and alpha was added to compete with the hp41c. hereafter, casio moved onto
basic programmable pocket
computers like the fx-700p,
although for a time, this model was concurrent with the fx-702p which wasn't sure whether it
was a pocket computer or a calculator.
the 10+2 display also accommodates 11 alpha characters
consisting of upper and lower case letters together with many
useful symbols. the display is clear for a dot matrix type.
there is no external contrast control, but the display
contrast could be adjusted with a potentiometer after opening
the unit is programmable with constant memory, totalling
of 512 steps and 22 memories (M00-M19 plus MF and M1F). this
number can be partitioned, trading in steps for more
memories. between 22 and 80 memories are allowed
corresponding to between 512 and 32 steps. the base memories
cannot be converted into more steps than 512. When you
altered the memory partition to gain more memory registers
(at the cost of 8 program steps for each memory register),
you always got an extra F Register for every 10 Memory
registers. If you had M20-M29, you also got M2F as a bonus.
Where this extra memory space came from, I don't know.
programmability is the same as the fx-502p with a comprehensive set of
instructions including 4 tests, isz & dsz
(increment/decrement and jump if zero) for compact loops,
labels, subroutines and indirect addressing. The original F
Register (located at the EXP key) was used for number
comparisons. There were 4 kinds of comparison: x=0, x?0, x=F
and x?F. Although the F register played an important role,
there was nothing special about the other F Registers.
Some people tuned their FXs by overclocking the chip. The
calculator went incredibly fast. Sad to say, this was also
the end of making music with this calculator.
writing and debugging program is a lot easier thanks to
the alpha ability. of course, text can be used within
programs to prompt the user for input and to augment output.
however, the unit does not have any kind of programmable
string variables or string manipulation.
there are 10 program slots and a program can be password
protected. this means it cannot be viewed or modified unless
the password is entered. perhaps this was intended for
commercial program libraries or simply to prevent someone
else wrecking your programs by accident. Password protection
was a fine feature but it didn't prevent the programs from
being completely cleared with [MODE][INV][MAC].
the keyboard functions include the usual scientific
functions, hyperbolic, 11 levels of brackets, 1-d statistics,
but fractions are missing. operation is algebraic entry, and
it is rather strange to use a alpha-numeric calculator that
is not formula entry. here, you press 5 then
tan rather than press tan then 5 like
most do today.
the unit is powered by 2 cr2032 lithium cells. this is a
step up over the older 502p, so it must require more power;
possibly for the display.
the 602p obviously did not require the programming
keyboard overlay of the fx-501/502p which decoded the program codes
into keys, but it did have the music overlay which enabled
sound to be played through the FA-1 cassette adapter (just
like the 502p).
The coding was the same as for the fx-501p. The Memory keys (Min, MR, M+,
M- and x-M) gave the length of the tone whereas the number in
the respective Memory register represented the note. The
value in the F Register determined the tempo. They even
thought of ties and breaks to make more sophisticated rhythms
possible! the 602p does not handle dotted notes the same way
as the 502p. On the 602p you have to tie a note to another
note using "-", for example a half-note "-" quarter-note.
Since the higher notes were slightly louder, you could
even use this unit as a sequencer for voltage controlled
analog sythesizers. You can hear one of these calculator
models in the song "Pocket Calculator" on the album "Computer
World" by KRAFTWERK.
Apparently, the password protection could be cracked the
following way :
print" test ";
during the run-loop you could press HTL, and then EXE, HLT
in small delays would because of a bug in the firmware
display the contents of the memory step by step and also the
password would be visible ( filed reverse unencrypted ) and
could be seen in the display.
- Additional information suplied to me by Peter Waslowski
- thanks peter.
- More info on the audio sent in by Gunnar Parment of
Sweden - thanks Gunnar.
- Password crack sent in by Aryan Blaauw - thanks