error on relative addressing octal in .lst file?
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While trying to recreate an octal dump from a small memory test from a DEC document (http://bitsavers.trailing-edge.com/pdf/dec/pdp11/xxdp/diag_listings/memory/MAINDEC-11-D1AA_BASIC_ADDRESS_TEST_UP_Mar70.pdf) containing relative addressing, I found the .lst file represents this as absolute addressing but with a ' added.
.ASECT
.=000200
START: MOV LOLMT,%0 ;INITIALIZE LOW LIMIT
WRITE: MOV %0,@%0 ;WRITE VALUE INTO ADDRESS
TST (0)+ ;JUST INCREMENT
CMP %0,#17500 ;TEST FOR DONE ALL MEMORY
BLOS WRITE ;NOT DONE
READ: CMP -(0),@%0 ;READ VALUE BACK FROM ADDRESS
BEQ CKON ;WAS VALUE OK?
HALT ;NO, HAVE ERROR-PRESS CONTINUE OR RESTART AT 200
CKON: CMP LOLMT,%0 ;TEST FOR DONE ALL MEMORY
BLO READ ;NOT DONE
HALT ;STORE "HALT" HERE TO STOP AFTER A PASS COMPLETION
BR START ;REPEAT TEST
LOLMT: .
.END
1 .ASECT
2 000200 .=000200
3 000200 016700 000236' START: MOV LOLMT,%0 ;INITIALIZE LOW LIMIT
4 000204 010010 WRITE: MOV %0,@%0 ;WRITE VALUE INTO ADDRESS
5 000206 005720 TST (0)+ ;JUST INCREMENT
6 000210 020027 017500 CMP %0,#17500 ;TEST FOR DONE ALL MEMORY
7 000214 101773 BLOS WRITE ;NOT DONE
8 000216 024010 READ: CMP -(0),@%0 ;READ VALUE BACK FROM ADDRESS
9 000220 001401 BEQ CKON ;WAS VALUE OK?
10 000222 000000 HALT ;NO, HAVE ERROR-PRESS CONTINUE OR RESTART AT 200
11 000224 026700 000236' CKON: CMP LOLMT,%0 ;TEST FOR DONE ALL MEMORY
12 000230 103772 BLO READ ;NOT DONE
13 000232 000000 HALT ;STORE "HALT" HERE TO STOP AFTER A PASS COMPLETION
14 000234 000761 BR START ;REPEAT TEST
15 000236 000236 LOLMT: .
15 .END
The original assembly listing had differences at two lines:
3 000200 016700 000032 START: MOV LOLMT,%0 ;INITIALIZE LOW LIMIT
11 000224 026700 000006 CKON: CMP LOLMT,%0 ;TEST FOR DONE ALL MEMORY
Hi @electrickery ... I have made some improvements to macro11 in my fork at https://github.com/rhialto/macro11 . You can try that version and see how it fares. Although I don't recall anything that might influence this.
The ' apostrophe in the listing indicates that that word is relocatable. With the dumpobj you can check what sort of relocation record is associated with it. It might be correct after all. Although I suspected you wanted pc-relative adressing such as the original listing seems to show (32(pc) and 6(pc), by the looks of it).
It has been a while since I worked on macro11, so I don't know what sort of addressing modes (if any) .ASECT is supposed to imply. But I think there are supposed to be directives that allow you to choose for some cases. But on the other hand, this macro11 doesn't implement them, I think.
Oh, and I have been trying to get the assembler to conform to the latest RSX version of macro11. Which may well have different defaults than anything from 1970... so maybe that can explain different adressing modes as well.
That diagnostic listing was assembled under PALX11, a PDP-11 cross-assembler running on a PDP-10, and following PAL-11 conventions used in the early 1970s.
This macro11 follows the later RT-11 MACRO11 and PDP-10 MACY11 (used by later diagnostics) convention of using the ' (apostrophe) to show a word will be relocated (depending on address mode) but the value indicated is the actual target memory address within the given program section (it could also be relocated if using the linker to combine multiple psects into a program).
So I would say the behavior is correct per late 1970s/early 1980s MACRO11 programming standards.
Don North, DEC PDP-11 Diagnostic Engineering, 1975-1978
Thanks for the responses. It is good to know the problem comes from my lack of knowledge and is not a bug in the code. Now I can concentrate on coercing macro11 to produce code I can spool into the Minc-23 via ODT. RTFM I suppose :-).
@Rhialto : I switched to your version of macro11 and it works ok, giving some more output.
Fred Jan
Closing, please follow Rhialto's fork as mentioned above.