Building a MIDI keytar

            .data
Transpose:        .byte    0
Octave:            .byte    0
VelCounters:    .space    49, 0
LastRawScanData:    .space    16, 0
RawScanData:    .space    16, 0

for(i = 0;i < 16;i++)
{
     LastRawScanData[i] = RawScanData[i];
}
for(i = index = 0;i < 8;i++)
{
    Set the AC238 address to the lower 3 bits of 'i'.
    1 or 2 tick delay...not sure. Will check the timing when the code is running.

    Set the latch enables on the AC573 to low.
    1 or 2 tick delay (Same as above)

    Set the latch enables on the AC573 to High.
    1 or 2 tick delay (Same as above)

    Set the latch enable #1 on the AC573 to Low.
    1 or 2 tick delay (Same as above)
    RawScanData[index++] = <Port byte>;

    Set the latch enable #1 on the AC573 to High.
    1 or 2 tick delay (Same as above)

    Set the latch enable #2 on the AC573 to Low.
    1 or 2 tick delay (Same as above)
    RawScanData[index++] = <Port byte>;

    Set the latch enable #2 on the AC573 to High.
    1 or 2 tick delay (Same as above)
}
// We now have the previous keyboard scan data as well as the current scan data.
// We can start comparing the bits and acting accordingly

// 7 bits used and only 7 out of 8 raw data registers used...
for(i = KeyIndex = 0;i < 7;i++)
{
BYTE KeyPress1 = RawScanData[i << 1],KeyPress2 = RawScanData[(i << 1) + 1];
BYTE LastKeyPress1 = LastRawScanData[i << 1],LastKeyPress2 = LastRawScanData[(i << 1) + 1];

    for(j = 0;j < 7;j++)
    {
// I'm going to do a bit by bit comparison. The notation I'm using here is not correct, but it illustrates the bit comparison...
          if (LastKeyPress1<j> != KeyPress1<j>)
          {
                if (KeyPress1<j> != 0)
                {
                    if (KeyPress2<j> == 0)
                            VelCounters[KeyIndex] = 0;
                }
                else
                {
                          // The key has been released...
                }
          }
          else if (KeyPress1<j> != 0 && KeyPress2<j> == 0)
               VelCounters[KeyIndex]++;
          else if (KeyPress1<j> != 0 && KeyPress2<j> != 0)
          {
// Send a Note on to the UART buffer...
          }
          KeyIndex++;
    }
}