u/Ready_Rain_2646

The case won't have any space to mount the original keyboard but I will share .step files so you will be able to modify it to use any modern replacement keyboard you desire.

I have finished phase 1, which is getting the amstrad's printer output as text in the serial monitor, that allowed me to develop the circuit . Circuit is some bi-directional logic level shifters between gpio of the raspberry pi and amstrad's printer port, they don't have to be bi-directional but those were cheaper and easier to replace than resistor voltage dividers and a transistor buffer. Now I'm trying to develop the second phase which is controlling a printer over a USB port using the USB host capabilities of the raspberry pi pico. However I can't get pico to print anything to the printer. I'm trying to solve this issue for the last few days, so if you can help me with the coding part of phase 2 I will be more than willing to share every detail. Also this project is just a start because the same methodology can be implemented to other computers such as commodore 64, Amiga and Atari ST.

Here is the working and tested phase 1 code:

// ==========================================

// Amstrad CPC 7-Bit Parallel Printer Capture

// ==========================================

// --- Pin Definitions ---

const int PIN\_STROBE = 1; // GP1 (Physical Pin 2) - CPC Pin 1 (/STROBE)

const int DATA\_PIN\_START = 2; // GP2 to GP8 (Physical Pins 4-11) - CPC Pins 2-8 (D0-D6)

const int PIN\_BUSY = 9; // GP9 (Physical Pin 12) - CPC Pin 10 or 11 (BUSY)

// --- Circular Buffer (FIFO) ---

// Safely passes bytes from the fast hardware interrupt to the main loop

const int BUFFER\_SIZE = 512;

volatile uint8\_t rx\_buffer\[BUFFER\_SIZE\];

volatile int head = 0;

volatile int tail = 0;

volatile bool character\_received = false;

// --- The Hardware Interrupt (The Data Catcher) ---

// Triggers automatically on the falling edge of STROBE

void strobeTriggered() {

// 1. Instantly pull BUSY high to tell the Amstrad CPC to hold

digitalWrite(PIN\_BUSY, HIGH);

// 2. Read the 7-bit data bus instantly.

// Shift right by 2 so GP2 moves to bit 0, then mask the lower 7 bits (0x7F).

uint8\_t incoming\_char = (gpio\_get\_all() >> DATA\_PIN\_START) & 0x7F;

// 3. Calculate the next buffer position

int next\_head = (head + 1) % BUFFER\_SIZE;

// 4. If buffer isn't full, push the character into the queue

if (next\_head != tail) {

rx\_buffer\[head\] = incoming\_char;

head = next\_head;

character\_received = true;

}

}

void setup() {

// Start Serial Monitor communication at 115200 baud

Serial.begin(115200);

// Wait up to 3 seconds for Serial Monitor to open after reset

unsigned long start\_wait = millis();

while (!Serial && (millis() - start\_wait < 3000));

// Configure the 7 data pins (GP2 through GP8) as inputs

for (int i = DATA\_PIN\_START; i < DATA\_PIN\_START + 7; i++) {

pinMode(i, INPUT);

}

// Configure Handshake pins

pinMode(PIN\_STROBE, INPUT\_PULLUP);

pinMode(PIN\_BUSY, OUTPUT);

digitalWrite(PIN\_BUSY, LOW); // Start in "Ready" state

// Attach the interrupt to trigger on STROBE's falling edge

attachInterrupt(digitalPinToInterrupt(PIN\_STROBE), strobeTriggered, FALLING);

Serial.println("=========================================================");

Serial.println(" Amstrad CPC Printerface, Phase 1 ");

Serial.println(" Circuit Design By Ege Ozpalamutcu & Code by Gemini ");

Serial.println(" Listening on GP1 (STROBE) & GP2-GP8 (DATA) & GP9 (BUSY)");

Serial.println("=========================================================");

}

void loop() {

// 1. Process characters from the circular buffer

while (tail != head) {

// Grab the oldest unread character from the queue

uint8\_t c = rx\_buffer\[tail\];

tail = (tail + 1) % BUFFER\_SIZE;

// Handle standard printable ASCII

if (c >= 32 && c <= 126) {

Serial.write(c);

}

// Handle Carriage Return (CR) and Line Feed (LF) for newlines

else if (c == 13 || c == 10) {

Serial.write(c);

}

// Handle the Escape character (used for printer commands)

else if (c == 27) {

Serial.print("<ESC>");

}

// Print everything else as a hex code for debugging

else {

Serial.print("\[0x");

if (c < 0x10) Serial.print("0"); // Leading zero

Serial.print(c, HEX);

Serial.print("\]");

}

}

// 2. Safely release BUSY only after /STROBE has returned HIGH

if (character\_received) {

// Wait until the CPC finishes its strobe pulse

if (digitalRead(PIN\_STROBE) == HIGH) {

delayMicroseconds(10); // Small settling delay for cable stability

character\_received = false;

digitalWrite(PIN\_BUSY, LOW); // Signal to CPC that we are ready for the next byte

}

}

}

I have finished phase 1, which is getting the amstrad's printer output as text in the serial monitor, that allowed me to develop the circuit . Circuit is some bi-directional logic level shifters between gpio of the raspberry pi and amstrad's printer port, they don't have to be bi-directional but those were cheaper and easier to replace than resistor voltage dividers and a transistor buffer. Now I'm trying to develop the second phase which is controlling a printer over a USB port using the USB host capabilities of the raspberry pi pico. However I can't get pico to print anything to the printer. I'm trying to solve this issue for the last few days, so if you can help me with the coding part of phase 2 I will be more than willing to share every detail. Also this project is just a start because the same methodology can be implemented to other computers such as commodore 64, Amiga and Atari ST.

Here is the working and tested phase 1 code:

// ==========================================

// Amstrad CPC 7-Bit Parallel Printer Capture

// ==========================================

// --- Pin Definitions ---

const int PIN\_STROBE = 1; // GP1 (Physical Pin 2) - CPC Pin 1 (/STROBE)

const int DATA\_PIN\_START = 2; // GP2 to GP8 (Physical Pins 4-11) - CPC Pins 2-8 (D0-D6)

const int PIN\_BUSY = 9; // GP9 (Physical Pin 12) - CPC Pin 10 or 11 (BUSY)

// --- Circular Buffer (FIFO) ---

// Safely passes bytes from the fast hardware interrupt to the main loop

const int BUFFER\_SIZE = 512;

volatile uint8\_t rx\_buffer\[BUFFER\_SIZE\];

volatile int head = 0;

volatile int tail = 0;

volatile bool character\_received = false;

// --- The Hardware Interrupt (The Data Catcher) ---

// Triggers automatically on the falling edge of STROBE

void strobeTriggered() {

// 1. Instantly pull BUSY high to tell the Amstrad CPC to hold

digitalWrite(PIN\_BUSY, HIGH);

// 2. Read the 7-bit data bus instantly.

// Shift right by 2 so GP2 moves to bit 0, then mask the lower 7 bits (0x7F).

uint8\_t incoming\_char = (gpio\_get\_all() >> DATA\_PIN\_START) & 0x7F;

// 3. Calculate the next buffer position

int next\_head = (head + 1) % BUFFER\_SIZE;

// 4. If buffer isn't full, push the character into the queue

if (next\_head != tail) {

rx\_buffer\[head\] = incoming\_char;

head = next\_head;

character\_received = true;

}

}

void setup() {

// Start Serial Monitor communication at 115200 baud

Serial.begin(115200);

// Wait up to 3 seconds for Serial Monitor to open after reset

unsigned long start\_wait = millis();

while (!Serial && (millis() - start\_wait < 3000));

// Configure the 7 data pins (GP2 through GP8) as inputs

for (int i = DATA\_PIN\_START; i < DATA\_PIN\_START + 7; i++) {

pinMode(i, INPUT);

}

// Configure Handshake pins

pinMode(PIN\_STROBE, INPUT\_PULLUP);

pinMode(PIN\_BUSY, OUTPUT);

digitalWrite(PIN\_BUSY, LOW); // Start in "Ready" state

// Attach the interrupt to trigger on STROBE's falling edge

attachInterrupt(digitalPinToInterrupt(PIN\_STROBE), strobeTriggered, FALLING);

Serial.println("=========================================================");

Serial.println(" Amstrad CPC Printerface, Phase 1 ");

Serial.println(" Circuit Design By Ege Ozpalamutcu & Code by Gemini ");

Serial.println(" Listening on GP1 (STROBE) & GP2-GP8 (DATA) & GP9 (BUSY)");

Serial.println("=========================================================");

}

void loop() {

// 1. Process characters from the circular buffer

while (tail != head) {

// Grab the oldest unread character from the queue

uint8\_t c = rx\_buffer\[tail\];

tail = (tail + 1) % BUFFER\_SIZE;

// Handle standard printable ASCII

if (c >= 32 && c <= 126) {

Serial.write(c);

}

// Handle Carriage Return (CR) and Line Feed (LF) for newlines

else if (c == 13 || c == 10) {

Serial.write(c);

}

// Handle the Escape character (used for printer commands)

else if (c == 27) {

Serial.print("<ESC>");

}

// Print everything else as a hex code for debugging

else {

Serial.print("\[0x");

if (c < 0x10) Serial.print("0"); // Leading zero

Serial.print(c, HEX);

Serial.print("\]");

}

}

// 2. Safely release BUSY only after /STROBE has returned HIGH

if (character\_received) {

// Wait until the CPC finishes its strobe pulse

if (digitalRead(PIN\_STROBE) == HIGH) {

delayMicroseconds(10); // Small settling delay for cable stability

character\_received = false;

digitalWrite(PIN\_BUSY, LOW); // Signal to CPC that we are ready for the next byte

}

}

}

I have finished phase 1, which is getting the amstrad's printer output as text in the serial monitor, that allowed me to develop the circuit . Circuit is some bi-directional logic level shifters between gpio of the raspberry pi and amstrad's printer port, they don't have to be bi-directional but those were cheaper and easier to replace than resistor voltage dividers and a transistor buffer. Now I'm trying to develop the second phase which is controlling a printer over a USB port using the USB host capabilities of the raspberry pi pico. However I can't get pico to print anything to the printer. I'm trying to solve this issue for the last few days, so if you can help me with the coding part of phase 2 I will be more than willing to share every detail. Also this project is just a start because the same methodology can be implemented to other computers such as commodore 64, Amiga and Atari ST.

Here is the working and tested phase 1 code:

// ==========================================

// Amstrad CPC 7-Bit Parallel Printer Capture

// ==========================================

// --- Pin Definitions ---

const int PIN_STROBE = 1; // GP1 (Physical Pin 2) - CPC Pin 1 (/STROBE)

const int DATA_PIN_START = 2; // GP2 to GP8 (Physical Pins 4-11) - CPC Pins 2-8 (D0-D6)

const int PIN_BUSY = 9; // GP9 (Physical Pin 12) - CPC Pin 10 or 11 (BUSY)

// --- Circular Buffer (FIFO) ---

// Safely passes bytes from the fast hardware interrupt to the main loop

const int BUFFER_SIZE = 512;

volatile uint8_t rx_buffer[BUFFER_SIZE];

volatile int head = 0;

volatile int tail = 0;

volatile bool character_received = false;

// --- The Hardware Interrupt (The Data Catcher) ---

// Triggers automatically on the falling edge of STROBE

void strobeTriggered() {

// 1. Instantly pull BUSY high to tell the Amstrad CPC to hold

digitalWrite(PIN_BUSY, HIGH);

// 2. Read the 7-bit data bus instantly.

// Shift right by 2 so GP2 moves to bit 0, then mask the lower 7 bits (0x7F).

uint8_t incoming_char = (gpio_get_all() >> DATA_PIN_START) & 0x7F;

// 3. Calculate the next buffer position

int next_head = (head + 1) % BUFFER_SIZE;

// 4. If buffer isn't full, push the character into the queue

if (next_head != tail) {

rx_buffer[head] = incoming_char;

head = next_head;

character_received = true;

}

}

void setup() {

// Start Serial Monitor communication at 115200 baud

Serial.begin(115200);

// Wait up to 3 seconds for Serial Monitor to open after reset

unsigned long start_wait = millis();

while (!Serial && (millis() - start_wait < 3000));

// Configure the 7 data pins (GP2 through GP8) as inputs

for (int i = DATA_PIN_START; i < DATA_PIN_START + 7; i++) {

pinMode(i, INPUT);

}

// Configure Handshake pins

pinMode(PIN_STROBE, INPUT_PULLUP);

pinMode(PIN_BUSY, OUTPUT);

digitalWrite(PIN_BUSY, LOW); // Start in "Ready" state

// Attach the interrupt to trigger on STROBE's falling edge

attachInterrupt(digitalPinToInterrupt(PIN_STROBE), strobeTriggered, FALLING);

Serial.println("=========================================================");

Serial.println(" Amstrad CPC Printerface, Phase 1 ");

Serial.println(" Circuit Design By Ege Ozpalamutcu & Code by Gemini ");

Serial.println(" Listening on GP1 (STROBE) & GP2-GP8 (DATA) & GP9 (BUSY)");

Serial.println("=========================================================");

}

void loop() {

// 1. Process characters from the circular buffer

while (tail != head) {

// Grab the oldest unread character from the queue

uint8_t c = rx_buffer[tail];

tail = (tail + 1) % BUFFER_SIZE;

// Handle standard printable ASCII

if (c >= 32 && c <= 126) {

Serial.write(c);

}

// Handle Carriage Return (CR) and Line Feed (LF) for newlines

else if (c == 13 || c == 10) {

Serial.write(c);

}

// Handle the Escape character (used for printer commands)

else if (c == 27) {

Serial.print("<ESC>");

}

// Print everything else as a hex code for debugging

else {

Serial.print("[0x");

if (c < 0x10) Serial.print("0"); // Leading zero

Serial.print(c, HEX);

Serial.print("]");

}

}

// 2. Safely release BUSY only after /STROBE has returned HIGH

if (character_received) {

// Wait until the CPC finishes its strobe pulse

if (digitalRead(PIN_STROBE) == HIGH) {

delayMicroseconds(10); // Small settling delay for cable stability

character_received = false;

digitalWrite(PIN_BUSY, LOW); // Signal to CPC that we are ready for the next byte

}

}

}

I came across this image of a proposed SCSI interface for the amstrad CPC in a forum. This was a while ago and I forgot where was that, but I just wonder is it really possible to connect SCSI devices to the amstrad cpc?

And could someone create a brand new one since the main IC here is still available for cheap amd rest of that looks like just logic IC's.

You basically glue a long stick to the stepper motor prior to loosen the screws, then with help of stick you can make very fine adjustments. You must use hot glue so later you can take it off easily using acetone. Also you need to move the end of the stick very slightly. Technically you are moving a larger circle connected to a smaller circle so the same amount of displacement at the circumference on bigger circle will correspond into a mich smaller angular change in the small circle