apple1-videocard-lib/demos/sdcard/cmd_dump.h

// global start_address
// global end_address

void comando_dump() {

   // send command byte
   send_byte_to_MCU(CMD_READ);
   if(TIMEOUT) return;

   // send filename
   send_string_to_MCU(filename);
   if(TIMEOUT) return;

   // response
   byte response = receive_byte_from_MCU();
   if(TIMEOUT) return;

   if(response == ERR_RESPONSE) {
      // error with file, print message
      print_string_response();
      return;
   }

   // get file length in tmpword
   receive_word_from_mcu();
   if(TIMEOUT) return;

   // 1234567890123456789012345678901234567890
   // 0000: 00 00 00 00 00 00 00 00 

   // get file bytes   
   byte row = 0;
   byte print_on = 1;
   for(word t=0;t!=tmpword;t++) {
      byte data = receive_byte_from_MCU();
      if(TIMEOUT) return;

      if(!(t>=start_address && t<=end_address)) continue;
      if(!print_on) continue;

      if(row == 0) {
         woz_putc('\r');
         woz_print_hexword(t);
         woz_puts(": ");
      }

      woz_print_hex(data);
      woz_putc(' ');

      row++;      
      row &= 7;
      
      if(apple1_readkey()) {
         woz_puts("*BRK*\r");
         print_on = 0;
      }
   }
}