Cool stuff. That's exactely what I had in mind. Can I have the source so I can modify it to work with my soundchip and perhaps have multiple channels?

Edit:
I want to add "hardware" pitch bending with different modes such as LFO, portamento and sweep. The sound processor will also have a lookuptable with musical notes' pitch values. If you write to one of the three dedicated "musical note" registers it will relay it to the freq-hi and lo registers and it will turn on the gate of the channel. This saves a lot of memory and time on the calculator side!

Example:
Calculator sends a NOTE ON normally:
00 ff - write ff (0-255) to register 00 (Freq Lo)
01 ff - write ff (0-255) to register 01 (Freq Hi)
04 17 - write TRIANGLE|GATE_ON to register 04 (Conrol reg)That's 6 bytes!

Calculator sends a NOTE ON with this new feature:
1D nn - write nn(0-255) to register 29That's only two bytes!

Yay more peripherals. We should have a hardware and schematics section on omnimaga!

As you might know I am working on a project that might enhance the way music is implemented in calculator games. I'm talking about an external soundchip. I can write registers via the linkport at 420 Bytes per second. Now I want to make a general purpose interrupt driven music player which can be inserted in any AXE source code with ease. I also need to figure out what the best file format looks like. I came up with this concept:
00aaaaaa dd - Write dd to register aa

01tttttt -- - Wait tt before executing the next instruction

10xxxxxx xx - Not implemented yet. (set speed?)

11xxxxxx - End of song marker.

I get transfer rates of 420bytes per second and a register write takes two bytes, so that's 210 register writes per second. This is without additional code for fetching commands. I want to use interrupt speed 4 or 6 (preferably 6 since it's similar to the TI83+ interrupt frequency)

What do you think? Any suggestions?

Edit: Now here is a more complex format for comparisson:
[Header] Name, Size, speed, etc.
[Instrument dumps] Timed register writes for each instrument
[Sequence] Order of patterns in the song
[Patterns] Pattern of notes, register writes, delays etc.


Just like the normal SE. I think those are interchangeable as well.

I don't think this thing has 153kB video ram (320*240*2 for 16 bit color). The images show that only a section of the screen can be used for full color graphics. I'm not sure if this is just a mode.

I tried to optimize the arduino code, but it's not getting an awful lot faster since my first optimization.
#include <SID.h>

// MACROs
#define PIN2H (PIND & 0B00000100)
#define PIN3L !(PIND & 0B00001000)
#define CLR(x,y) (x&=(~(1<<y)))
#define SET(x,y) (x|=(1<<y))

SID mySid;

void setup()
{
  pinMode(2,INPUT);
  pinMode(3,INPUT);
  mySid.begin();
}

byte n=0;
int timer=0;
byte count=0;
byte get=B00000000;
int addrval[2] = {0};

void loop()
{
  do{
    do
    {
      if (PIN3L)          // If the clock pin is LOW
      {
        if (PIN2H)        // And the data pin is HIGH
        {
          CLR(get,count); // CLEAR BIT
        }
        else              // otherwise
        {
          SET(get,count); // SET BIT
        }
        count++;          // Increase the bit counter
       
        while(PIN3L)      // Wait until the clock pin goes HIGH again
        {
        timer++;          // Increase the timeout timer
          if (timer==500){// Timeout at 500 loops
            n=count=0;    // Reset counters
            break;        // Break free
          }
        }
        timer=0;          // Reset the timeout timer
      }
    }while(count!=8);     // Loop again when the bit counter has not reached 8 bits yet
    addrval[n]=get;       // Otherwise store the received byte in an array in cell n
    n++;                  // Increase the byte counter
    count=0;              // Reset the bit counter
  }while(n!=2);           // Loop again when the byte counter has not reached two bytes yet
                          // Otherwise write the value to the register.
  mySid.set_register(addrval[0], addrval[1]);
  n=0;                    // Reset the byte counter
}Can someone tell me what to optimize?

I'm not going to rush this.