Hey #retrocomputing Fediverse
I've got a piece of early x86 assembly that doesn't look like x86 assembly. It resembles 8080 assembly, except the instructions are clearly of 8086. I'd like to figure out what tool might have once assembled it.
Perhaps the clearest identifying feature I see is the use of a DM directive, possibly as 'data message', apparently used to embed string literals into the code. Which dialect of early 8086 assembler might have defined a DM directive?
Another unusual feature I see is ALIGN directive without parameters. The semantics is not immediately clear to me; I'd speculate that it's intended to trigger even alignment.
The result of the assembly was likely supposed to be an unheadered COM image or possibly an equivalent; it looks unlikely that any linker would have been applied to the output.
The latest timestamp mentioned in the comments is August 18, 1982, and it describes the target platform as 'Microsoft's MS-DOS 8086'. It is likely a port from CP/M-86.
Riley S. Faelan /
npub1um…24x8w
2024-06-05 22:59:41
Author Public Key
npub1umlpwengjh0wv8prdfwhrlg49j6kfqmmksyqymjj6cue3etya5sqk24x8wPublished at
2024-06-05 22:59:41Event JSON
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"content": "Hey #retrocomputing Fediverse\n\nI've got a piece of early x86 assembly that doesn't look like x86 assembly. It resembles 8080 assembly, except the instructions are clearly of 8086. I'd like to figure out what tool might have once assembled it.\n\nPerhaps the clearest identifying feature I see is the use of a DM directive, possibly as 'data message', apparently used to embed string literals into the code. Which dialect of early 8086 assembler might have defined a DM directive?\n\nAnother unusual feature I see is ALIGN directive without parameters. The semantics is not immediately clear to me; I'd speculate that it's intended to trigger even alignment.\n\nThe result of the assembly was likely supposed to be an unheadered COM image or possibly an equivalent; it looks unlikely that any linker would have been applied to the output.\n\nThe latest timestamp mentioned in the comments is August 18, 1982, and it describes the target platform as 'Microsoft's MS-DOS 8086'. It is likely a port from CP/M-86.",
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