im using a Boss Dr5 as the master, sending midi to arduinoboy in to trigger mGB and using the out of the ABoy as a thru to start the internal sequencer in the bassline engine of the sammich, it is working very well,

Yeah that makes sense, without the gate flag active a channel's ADSR envelope won't reset.   Any subsequent notes will fade out with the envelope length until you reset the gate again.  This can be used to do a "fall off" effect, but it depends on the tracker if you'll get that result.  (some require a note slide effect to be active or something)

sorted
"The note will only be played if the gate flag is set."

while im at it, can anyone tell me how to mute steps in the bassline sequencer mode, i cant seem to find out how to in the manual....

awesome , cheers

It's very possible, read about multi mode

http://www.ucapps.de/midibox_sid_manual_m.html

Is it possible to create an entire song on a sammichsid, ie have drums, bass and lead (for example) all play at the time , and if so can anyone piont me in the right direction of how to achieve this....