You have V4 sources? The TUHS archive doesn't have them that I've seen... Warner On Mon, Jan 6, 2020, 2:38 PM Clem Cole wrote: > Some day .... So I took a peak at the V5 crt0.s and guess what -- it > matches! > > On Mon, Jan 6, 2020 at 4:08 PM Clem Cole wrote: > >> You got my curiosity up and found the V5 and V6 source code (I did not >> have V4 easy to get, where I am today) ;-) >> >> A big clue of it being C will be having crt0.s (below) in the first few >> bytes of the disassembled code. We see the a.out header (i.e. start at >> offset 20 for the code) and look what's there. I'm going to guess that is >> at 046 is the address of _main, from the call instruction at address 034. >> The Trap 1 is a sys exit @ address 044. >> But .. the V6 crt0.s source has a call to _exit, which is lacking in the >> binary below. So it means that the binary was not created with the C >> runtime and probably not the v6 C compiler in the sources. So I took a >> peak at the V6 crt0.s and guess what -- it matches! >> >> So, I'm going to guess the binary was compiled and linked with an earlier >> compiler. Ao ... if I had to guess, the programs are similar, but possibly >> different. >> >> % more wump.das >> ; >> ; pdp11dasm version 0.0.3 >> ; disassembly of wump >> ; >> 000000: 000407 br 20 ; .. >> ; >> 000002: 005334 dec @(r4)+ ; \. >> 000004: 004524 jsr r5,(r4)+ ; T. >> 000006: 002312 bge 37777777634 ; J. >> 000010: 000000 halt ; .. >> 000012: 000000 halt ; .. >> 000014: 000000 halt ; .. >> ; >> 000016: 000001 wait ; .. >> 000020: 170011 setd ; .p >> 000022: 010600 mov r6,r0 ; .. >> 000024: 011046 mov (r0),-(r6) ; &. >> 000026: 005720 tst (r0)+ ; P. >> 000030: 010066 000002 mov r0,2(r6) ; 6... >> 000034: 004767 000006 call 46 ; w... >> 000040: 022626 cmp (r6)+,(r6)+ ; .% >> 000042: 005000 clr r0 ; .. >> 000044: 104401 trap 1 ; .. >> 000046: 004567 005174 jsr r5,5246 ; w.|. >> 000052: 005746 tst -(r6) ; f. >> 000054: 012716 011230 mov #11230,(r6) ; N... >> 000060: 004737 002776 call @#2776 ; _.~. >> 000064: 004767 002262 call 2352 ; w.2. >> 000070: 022700 000171 cmp #171,r0 ; @%y. >> 000074: 001027 bne 154 ; .. >> 000076: 005004 clr r4 ; .. >> 000100: 010400 mov r4,r0 ; .. >> 000102: 006300 asl r0 ; @. >> 000104: 005760 005334 tst 5334(r0) ; p.\. >> 000110: 001421 beq 154 ; .. >> 000112: 032704 000001 bit #1,r4 ; D5.. >> 000116: 001403 beq 126 ; .. >> 000120: 012716 000024 mov #24,(r6) ; N... >> 000124: 000402 br 132 ; .. >> ; >> 000126: 012716 000003 mov #3,(r6) ; N... >> 000132: 010400 mov r4,r0 ; .. >> 000134: 006300 asl r0 ; @. >> 000136: 016046 005334 mov 5334(r0),-(r6) ; &.\. >> 000142: 004737 002776 call @#2776 ; _.~. >> >> >> >> >> >> V6: s4/crt0.s: >> / C runtime startoff >> >> .globl savr5 >> .globl _exit >> >> .globl _main >> >> start: >> setd >> mov sp,r0 >> mov (r0),-(sp) >> tst (r0)+ >> mov r0,2(sp) >> jsr pc,_main >> mov r0,(sp) >> jsr pc,*$_exit >> sys exit >> >> .bss >> savr5: .=.+2 >> >> V5: s4/crt0.s: >> / C runtime startoff >> >> .globl savr5 >> >> .globl _main >> >> start: >> setd >> mov sp,r0 >> mov (r0),-(sp) >> tst (r0)+ >> mov r0,2(sp) >> jsr pc,_main >> cmp (sp)+,(sp)+ >> clr r0 >> sys exit >> >> .bss >> savr5: .=.+2 >> >> On Mon, Jan 6, 2020 at 1:48 PM Warner Losh wrote: >> >>> >>> >>> On Mon, Jan 6, 2020 at 11:38 AM Will Senn wrote: >>> >>>> On 1/6/20 12:29 PM, Warner Losh wrote: >>>> >>>> The good news is that disassembly will tell you right away if it was >>>> written in C or not. >>>> >>>> >>>> OK. I give up. How? >>>> >>> >>> Generally, the C compiler generates code that's quite distinctive (at >>> least PCC does, not sure about Dennis' compiler). People writing free >>> assembler tend to do really weird things for function entry / return. >>> >>> And it will likely tell you if it's some weird wrapper around another >>> binary, though that wasn't too common at bell labs. >>> >>> Warner >>> >>