| 1 | .so mnx.mac
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| 2 | .TH DIS88 9
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| 3 | .CD "dis88 \(en disassembler [IBM]"
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| 4 | .SX "dis88\fR [\fB\(eno\fR] \fIinfile\fR [\fIoutfile\fR]"
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| 5 | .FL "\(eno" "List the object code along with the assembly code"
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| 6 | .EX "dis88 a.out >listing" "Disassemble \fIa.out\fR"
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| 7 | .EX "dis88 \(eno a.out listing" "Ditto, but with object code"
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| 8 | .PP
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| 9 | \fIDis88\fR disassembles 8088 object code to the assembly language format
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| 10 | used by
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| 11 | .MX .
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| 12 | It makes full use of
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| 13 | symbol table information, supports separate
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| 14 | instruction and data space, and generates synthetic labels when needed.
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| 15 | It does not support 8087 mnemonics, symbolic data segment references, or
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| 16 | the ESC mnemonic.
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| 17 | .PP
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| 18 | The program is invoked by:
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| 19 | .HS
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| 20 | .Cx "dis88 [\(eno] infile [outfile]"
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| 21 | .HS
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| 22 | The \(eno flag causes object code to be listed.
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| 23 | If no outfile is given, \fIstdout\fR is used.
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| 24 | .PP
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| 25 | The text segment of an object file is always padded to an even address.
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| 26 | In addition, if the file has split I/D space, the text segment will be padded
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| 27 | to a paragraph boundary (i.e., an address divisible by 16). Due to padding, the
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| 28 | disassembler may produce a few spurious, but harmless, instructions at the end
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| 29 | of the text segment.
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| 30 | .PP
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| 31 | Because the information to which initialized data refers cannot generally
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| 32 | be inferred from context, the data segment is treated literally. Byte values
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| 33 | (in hexadecimal) are output, and long stretches of null data are represented by
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| 34 | appropriate \fI.zerow\fR pseudo-ops.
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| 35 | Disassembly of the bss segment, on the other
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| 36 | hand, is quite straightforward, because uninitialized data is all zero by
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| 37 | definition.
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| 38 | No data is output in the bss segment, but symbolic labels are output
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| 39 | as appropriate.
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| 40 | .PP
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| 41 | The output of operands in symbolic form is complicated somewhat by the
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| 42 | existence of assembler symbolic constants and segment override opcodes. Thus,
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| 43 | the program's symbol lookup routine attempts to apply a certain amount of
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| 44 | intelligence when it is asked to find a symbol. If it cannot match on a symbol
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| 45 | of the preferred type, it may output a symbol of some other type, depending on
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| 46 | preassigned (and somewhat arbitrary) rankings within each type. Finally, if
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| 47 | all else fails, it will output a string containing the address sought as a hex
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| 48 | constant. For user convenience, the targets of branches are also output, in
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| 49 | comments, as hexadecimal constants.
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| 50 | .SS "Error Messages"
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| 51 | .PP
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| 52 | Various error messages may be generated as a result of problems encountered
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| 53 | during the disassembly.
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| 54 | They are listed below
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| 55 | .HS.
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| 56 | .in +3.20i
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| 57 | .ta +2.75i +0.2i
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| 58 | .ti -2.95i
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| 59 | Cannot access input file \(en Input file cannot be opened or read
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| 60 | .ti -2.95i
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| 61 | Cannot open output file \(en Output file cannot be created
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| 62 | .ti -2.95i
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| 63 | Input file not in object format \(en Bad magic number
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| 64 | .ti -2.95i
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| 65 | Not an 8086/8088 object file \(en CPU ID of the file header is incorrect
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| 66 | .ti -2.95i
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| 67 | Reloc table overflow \(en Relocation table exceeds 1500 entries
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| 68 | .ti -2.95i
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| 69 | Symbol table overflow \(en Symbol table exceeds 1500 entries
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| 70 | .ti -2.95i
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| 71 | Lseek error \(en Input file corrupted (should never happen)
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| 72 | .ti -2.95i
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| 73 | Warning: no symbols \(en Symbol table is missing (use ast)
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| 74 | .ti -2.95i
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| 75 | Cannot reopen input file \(en Input file was removed during execution
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| 76 | .in -3.20i
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| 77 | .SS "Author"
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| 78 | .PP
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| 79 | \fIDis88\fR was written and
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| 80 | copyrighted by G. M. Harding and is included here by permission. It may be
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| 81 | freely redistributed provided that complete source code, with all copyright
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| 82 | notices, accompanies any redistribution. This provision also applies to any
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| 83 | modifications you may make. You are urged to comment such changes, giving,
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| 84 | as a minimum, your name and complete address.
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