Casio Sound Kids 01 (KS-01) (toy keyboard with cards)

This rare toy keyboard of 1991 (embossed case date) was the likely most crippled Casio SA-series variant. It has no rhythms and only 10 preset sounds selected by plastic cards.

Don't expect the cards to be anything complex. They only push each a tiny button inside the card slot during insertion. Historically most important is that its case design obviously inspired the (in)famous Chinese My Music Center, which in 1990th became much more widespread than the rather obscure KS-01 itself.

main features:

eastereggs:

notes:

This thing is so poorly designed, that with cards inserted halfway, some keyboard keys become monophonic by lack of matrix diodes, because the card holds its OBS preset sound button down. A fully inserted card releases its button, hence an already inserted card can not be sensed during power-on. Very unusual for such a toy is that it has an AC-adapter jack but no headphone, however with no batteries inserted, the case rumbles badly at certain note pitches.

My KS-01 initially didn't work. It behaved like a stuck "volume up" button, but it turned out that there was a corrosion voltage of 150mV across its pins, because of acid or salt residues on the PCB. Battery contacts are not corroded, so possibly a child had spilled something inside. Washing the silicone contact strips with dishwashing detergent and cleaning the carbon contact area of the PCB with isopropanol fixed it.

The 10 preset sounds correspond to Casio SA-1. Different are 'violin' (duller, = from SA-35?), 'trumpet' (duller, less chorus, = variant 3 of SA-35?). The "glockenspiel" card is 'bells'. The "ambulance" here has same siren but on the rightmost key an additional car horn. The 'chicken' (depicts a yellow chicken) is a short bird tweet with percussive attack (only 1 pitch, like highest 'pearl drop' note without echo or SA-35 'chirp' in higher). The 'drumkit' card plays 4 sounds {mid synth tom, snare, closed hihat, triangle}.

The demo is the Japanese children song "Aye-aye" (music by Seiichiro Uda, lyrics by Yumi Aida) arranged as a long and nicely arranged comedy tune in slapstick B/W movie style with honking notes and the full palette of (on this keyboard unreachable) SA-series effect sounds. The melody is also known as song 2 from the arcade game "Turtles" by Stern/Sega (1981, aka Sega "Turpin", main theme of Konami version).
 

circuit bending details

The Casio SA-1 is built around the CPU "OKI M6387-10".
The card slot contacts are implemented as individual OBS preset sound buttons. Each card presses and releases one corresponding button during insertion.

keyboard matrix

The matrix layout is obviously based on Casio SA-1, but with OBS preset sound contacts instead of cipher buttons. (Because all 10 are populated, I did not find irregularities like in KS-02.) Most interesting is the hidden rhythm set that resembles SA-1 but is full of glitches.
 
11 KI0
12 KI1
13 KI2
14 KI3
15 KI4
16 KI5
17 KI6
18 KI7
 
CPU pin
in 0
in 1
in 2
in 3
in 4
in 5
in 6
in 7
in / out
 
o
F3
o
F#3
o
G3
o
G#3
o
A3
o
A#3
o
B3
o
C4
out 0
30 KO0
o
C#4
o
D4
o
D#4
o
E4
o
F4
o
F#4
o
G4
o
G#4
out 1
29 KO1
o
A4
o
A#4
o
B5
o
C5
o
C#5
o
D5
o
D#5
o
E5
out 2
28 KO2
o
F5
o
F#5
o
G5
o
G#5
o
A5
o
A#5
o
B5
o
C6
out 3
27 KO3
O.
piano
O.
pipe organ
O.
violin
O.
clarinet
O.
trumpet
tempo
+
volume
+
rhythm select
out 4
26 KO4
O.
bells
O.
ambulance
O.
laser beam
O.
bird
O.
drumkit
stop
tempo
-
volume
-
out 5
25 KO5
O.
piano
O.
pipe organ
O.
violin
O.
clarinet
O.
trumpet
demo
demo
demo
out 6
24 KO6
-
-
-
-
-
-
-
polyphony 4
[diode]
out 7
23 KO7

The input lines are active-high, i.e. react on +Vs. Any functions can be triggered by a non- locking switch in series to a diode from one "out" to one "in" pin.
 

legend:
"o"
 = keyboard key
O.
 = preset sound ('orchestra')
orange
background 		 = easteregg
grey 
background		 = unconnected doublet

eastereggs:

Like in SA-1, wiring a button at KO4->KI7 selects 32 rhythm patterns through keyboard keys. Also tempo +/- (KO4->KI5, KO5->KI6) and stop button (KO5->KI5) are there. But although the rhythm set resembles SA-1, it obviously differs and is full of glitches. So some patterns run unbalanced by containing a pause before they repeat. Others honk on a tekkno-like staccato tone, which may result of a changed internal preset sound order that replaced a drum or hihat with a melodic instrument. But even recognizable patterns are often on different keys than in SA-1. Likely some were redesigned to act as fill-ins for its long and complex demo song of KS-01that uses literally all bells and whistles and so may have reached numerical limits of the internal sequencer or rom size and so misused rhythm patterns as subroutines.

Also here a diode at KO-7->KI7 (sensed during power-on) enables 4-note polyphony, which makes note mess by lack of individual key matrix diodes.

A bigger Sound Kids keyboard with ROM-Pack slot was Casio KS-02.
 

 removal of these screws voids warranty...    
WarrantyVoid
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