Casio FX-602P Scientific programmable calculator

Description

Expansion Port

PIN	SYMBOL	FUNCTION
1	CE	Chip enable output, active high
2	GND	Ground (positive supply voltage rail)
3	D8	Data input/output (bi-directional)
4	CONT	-3V when operational, 0V when stand-by
5	OP	Selects the Command Register (OP=0) or Data Register (OP=1)
6	VDD1	-3V (negative supply voltage rail)
7	SP	Clock output

Cassette Interface

The FA-2 cassette interface uses the same HD43110 controller chip as the FA-3 one, so the tape interface protocol used by the FX-700P applies to the FX-602P as well.

The FA-2 Cassette Interface is designed for the FX-601P, FX-602P, and FX-702P calculators. It can play musical notes as well.

Addition commands

CODE	FUNCTION	DESCRIPTION
001100  Wait            This command suspends the data transfer for a while when reading from the tape. The calculator issues it after loading of the file header, then reads a single data bit. The meaning of this value is unknown to me (the interface always returns 1).
110100  Counter         This command defines the frequency of the music tone. It expects an 8-bit value (the least significant bit first).
frequency = 32768Hz/value
001110  Play the sound  After sending this command, signal of frequency specified by the Counter command appears on the MIC output.
111110  Stop the sound  This command terminates generating the music tone.
111100  Close           Apart from closing the communication channel, this command has an additional function. After sending it, the calculator can read a single data bit which returns the Cal/Music switch state (Cal=0, Music=1). Otherwise, this switch doesn't seem to influence the function of the controller.

Music playing example

1.  OP=0 111100         ;test the Cal/Music switch
    OP=1 1              ;returned value=1,
                        ;means the switch in the "Music" position
2.  OP=0 111110		;stop the sound
3.  OP=0 110100         ;preset the counter according to the note pitch
    OP=1 01001010       ;value=0x52 (frequency=400Hz)
4.  OP=0 001110         ;play the sound
5.  delay depending on the tempo
6.  goto 1, until all notes played
7.  OP=0 000000         ;reset
8.  OP=0 111110		;stop the sound

Printer interface

The FP-10 printer command codes have the last transmitted bit set.

Available commands

CODE     FUNCTION       DESCRIPTION
000011  Presence        After sending this command, the calculator reads a single data bit. Returned value=1 means the printer is present.
011001  ???             This command always appears immediately before the Presence command, function unknown.
100001  Read status     After sending this command, the calculator reads a single data bit. Returned value=0 means the printer is busy, while 1 means it's ready to accept data.
110011  Send control    This command is followed by a printer control byte. Order of bits:
                        the start bit=0
                        8 data bits (the least significant bit first)
                        the parity bit
                        2 stop bits=1
                        4 "don't care" bits (the FX-602P sends 1010)
                        The busy/ready status needs to be tested with the Read status command before any data transfer.
010011  Send data       This command is followed by a data byte. Otherwise as the Send control command.

Known printer control codes

CODE	FUNCTION
0x10	Prints a string using the FX-602P alpha mode.
0x11	Prints a number using the FX-602P numbers mode.
0x13	Function unknown, sent by the FX-602P to the printer after power-on.
0x1F	Terminates strings sent by the FX-602P to the printer.
0x29	Selects the FX-702P printing mode.

Power-on sequence

1.  OP=0 011001         ;unknown Code 011001
    OP=0 000011         ;test for printer presence
    OP=1 0 or 1         ;returns 1 when printer present
2.  OP=0 000101         ;read status - repeat this sequence,
    OP=1 0 or 1         ;until the interface returns 1
3.  OP=0 010010         ;this command seems to be directed to the tape
                        ;interface, perhaps it fixes some interaction
                        ;issues
4.  OP=0 011001         ;unknown Code 011001
    OP=0 000011         ;test for printer presence
    OP=1 0 or 1         ;returns 1 when printer present
5.  OP=0 110011         ;send control code 0x13
    OP=1 0110010001111010
6.  OP=0 000101         ;read status - repeat this sequence,
    OP=1 0 or 1         ;until the interface returns 1
7.  OP=0 010010         ;command for the tape interface
8.  OP=0 011001         ;unknown Code 011001
    OP=0 000011         ;test for printer presence
    OP=1 0 or 1         ;returns 1 when printer present
9.  OP=0 110011         ;send control code 0x10
    OP=1 0000010001111010
10. OP=0 010010         ;command for the tape interface
    OP=0 000000         ;reset
    OP=0 111110         ;command for the tape interface

The FX-702P sends only the Reset command after power-on.

Printing example

1.  OP=0 011001         ;unknown Code 011001
    OP=0 000011         ;test for printer presence
    OP=1 0 or 1         ;returns 1 when printer present
2.  repeat the above test
3.  OP=0 110011         ;send control code 0x11
    OP=1 0100010000111010
4.  OP=0 000101         ;read status - repeat this sequence,
    OP=1 0 or 1         ;until the interface returns 1
5.  OP=0 010010         ;command for the tape interface
6.  OP=0 011001         ;unknown Code 011001
    OP=0 000011         ;test for printer presence
    OP=1 0 or 1         ;returns 1 when printer present
7.  OP=0 010011         ;send data (0xFF in this example)
    OP=1 0111111110111010
8.  OP=0 000101         ;read status - repeat this sequence,
    OP=1 0 or 1         ;until the interface returns 1
9.  goto 5, until all data bytes sent
10. OP=0 010010         ;command for the tape interface
11. OP=0 011001         ;unknown Code 011001
    OP=0 000011         ;test for printer presence
    OP=1 0 or 1         ;returns 1 when printer present
12. OP=0 110011         ;send control code 0x1F
    OP=1 0111110001111010
13. OP=0 000101         ;read status - repeat this sequence,
    OP=1 0 or 1         ;until the interface returns 1
14. OP=0 010010         ;command for the tape interface
    OP=0 000000         ;reset

The FX-702P calculator skips the 010010 commands.

FX-602P numbers mode

Numbers are printed using following sequence:
1. control command 0x11
2. eight data bytes
3. control command 0x1F

Character enconding

CODE	CHARACTER
0x0-0x9	digits 0-9
0xA	decimal point
0xE	minus sign
0xF	space

FX-602P alpha mode

Strings are printed using following sequence:
1. control command 0x10
2. data bytes
3. control command 0x1F

Image