I have this sysex string and need to find out how the last byte (18) before F7 was calculated.

F0 07 00 78 09 00 67 00 01 00 00 18 00 45 71 75 61 6C 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 3F 79 60 18 F7


thanks

Gosh, I've had to dig a bit for this one..

This link is to a PDF of part of the Kurzweil K2000 manual:
http://www.brown.edu/Departments/Music/Music11/K2000_Manual/30SysEx.pdf

It describes the SysEx format.

In summary, the sysex stream is organised like this

"F0 07 00" is the header. F0 means "SysEx", "07" means "Kurzweil" and "00" is the device ID which may be set to any number you like via a the menu on the K2000 (so the pdf says); I assume 0 is the default setting.

"78" is mandatory and is the Kurzweil Product Identifier; 78 means "K2000", spookily enough

"09" is message type. I hope this means something to you!

The bytes after this message type through to (but not including) the checksum are the data bytes.

The checksum (18) is the bottom 7 bits of the sum of the preceding data bytes. (i.e 00 67 00 01 ...... 37 79 60)

I've run the data bytes through some code I've written. I get this check sum to be 11 (hex); 17 (in decimal)

Hope this helps!