/** * Terminal interface. * This sketch allow an Arduino to be used as a terminal to log into Pat80. * The Arduino is connected to the Pat80 I/O bus and to the terminal computer via USB. * The Arduino IDE serial monitor is used to send and receive commands to the Z80. */ // EN 2 // Active low // WR 11 // Active low // DATA BUS IS: 3, 4, 5, 6, 7, 8, 9, 10; byte incomingBuffer = 0; // Incoming from computer, to the Pat80 byte outgoingBuffer = 0; // Outgoing to computer, from the Pat80 void setup() { Serial.begin(2000000); Serial.println("Pat80 terminal"); DDRD = B00000010; // Port D (used arduino pins 2 (EN) and 3 to 7 (DATA)) is input. Avoid changing serial pins. DDRB = B00000000; // Port B (used arduino pins 8 to 10 (DATA) and 11 (WR)) is input attachInterrupt(digitalPinToInterrupt(2), onClk, CHANGE); } void loop() { if (Serial.available() > 0) { incomingBuffer = Serial.read(); } if (outgoingBuffer != 0) { if ((outgoingBuffer >= 8 && outgoingBuffer <= 13) || (outgoingBuffer >= 32 && outgoingBuffer <= 127)) { // Printable character Serial.print((char)outgoingBuffer); } else { // Non-printable character Serial.print("[0x"); Serial.print(outgoingBuffer, HEX); Serial.print("]"); } } } void onClk() { // In any case, return to high impedance state DDRD = B00000010; DDRB = B00000000; if (PIND & B00000100 == B00000000) { // EN is LOW: Clock pulse started if (PINB & B00001000 == B00001000) { // WR is HIGH (Pat80 wants to Read (we send data)) DDRD = DDRD | B11111000; // Port D (arduino pins 3 to 7) is output. In or to preserve serial pins and interrupt pin DDRB = B00000111; // Port B (0,1,2) = pins 8,9,10 output // Split byte to two parts PORTD = incomingBuffer << 3; PORTB = incomingBuffer >> 5; } else { // Pat80 wants to Write (we receive data) outgoingBuffer = (PIND >> 3) | (PINB << 5); // Compose the final byte from the two parts } } }