rtVAX 300.

Most used? That would probably be a CALLS/CALLG call, in which case the arguments are in memory, on the stack for CALLS but potentially anywhere for CALLG. But, what little looking at the code I've done gives me the impression it uses jsb/rsb style calls a lot more than many things do, in which case the argument could be pretty much anywhere. For example, from isa300-rom... 12b4: .byte 21 12b5: .ascii "\n\n\r%VAXELN system initializing\n\n\r" 1e29: movab 0x12b4,r1 1e2e: bsbw 0x3b07 ...the code at 3b07 takes its argument in r1: 3b07: movzbl (r1)+,-(sp) 3b0a: beql 0x3b23 3b0c: brb 0x3b19 3b0e: movzwl (r1)+,-(sp) 3b11: beql 0x3b23 3b13: brb 0x3b19 3b15: movzbl $ff,-(sp) 3b19: movzbl (r1)+,r0 3b1c: beql 0x3b23 3b1e: bsbb 0x3ab7 3b20: sobgtr (sp),0x3b19 3b23: tstl (sp)+ 3b25: rsb Unfortunately, while this particular piece of code is clearly a string print routine, it's not much help, because the code at 3ab7 ends up calling through a run-time-set pointer: 3ab7: tstl (sp) 3ab9: blss 0x3ac6 3abb: pushl r0 3abd: pushl $3 3abf: calls $2,*04c8(r8) (there's more, of course, but it's not much more helpful). So the answer is a definite "maybe". :( /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTML mouse at rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B