Question on QS sysex specs doc

Posted by Jason Peter on November 09, 1997 at 21:34:18:

I am somewhat confused by the QS8 Sysex doc that I have from Alesis. I am trying to interpret what the heck they are talking about on the first page.

Here is the portion of the doc that I am having trouble understanding:

is in a packed format in order to optimize data transfer. Eight MIDI bytes are used to transmit each block of 7 QS data bytes. If the 7 data bytes are looked at as one 56-bit word, the format for transmission is eight 7-bit words beginning with the most significant bit of the first byte, as follows:

SEVEN QUADRASYNTH BYTES:
0: A7 A6 A5 A4 A3 A2 A1 A0
1: B7 B6 B5 B4 B3 B2 B1 B0
2: C7 C6 C5 C4 C3 C2 C1 C0
3: D7 D6 D5 D4 D3 D2 D1 D0
4: E7 E6 E5 E4 E3 E2 E1 E0
5: F7 F6 F5 F4 F3 F2 F1 F0
6: G7 G6 G5 G4 G3 G2 G1 G0

TRANSMITTED AS:
0: 0 A6 A5 A4 A3 A2 A1 A0
1: 0 B5 B4 B3 B2 B1 B0 A7
2: 0 C4 C3 C2 C1 C0 B7 B6
3: 0 D3 D2 D1 D0 C7 C6 C5
4: 0 E2 E1 E0 D7 D6 D5 D4
5: 0 F1 F0 E7 E6 E5 E4 E3
6: 0 G0 F7 F6 F5 F4 F3 F2
7: 0 G7 G6 G5 G4 G3 G2 G1

First of all when they say 7 QS bytes are they talking about the lines marked as 0: through 6:?

If so, then how are these lines constituting a byte? Each one looks like it has eight bytes to me - except of course for the seventh line that has hex numbers that start with G's! What is this?!?!?

I understand conceptually the process of taking a series of 7 bytes and making 8 7 bit bytes out of them, but this example baffles me to no end.

Please help!!

Follow Ups:

• Re: Question on QS sysex specs doc Dan Halbert 11/10/97 (3)
  • Re: Question on QS sysex specs doc Jason Peter 11/10/97 (1)
    • Re: Question on QS sysex specs doc Dan Halbert 11/11/97 (0)
  • Re: Question on QS sysex specs doc Dan Halbert 11/10/97 (0)