NETPIC (Jim Tucker)

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File Format
Name NETPIC (Jim Tucker)
Ontology
Extension(s) .npx, others
Released 1995

NETPIC is a DOS utility developed by Jim Tucker. Its main feature is to convert a GIF image file to a COM file that, when executed, displays the image.

Discussion

The generated COM file can optionally use an ASCII-only encoding suitable for inclusion in an email. See Executable envelopes#Transfer-encoded executables for other executable formats of this sort.

Early versions (pre-v1.3) have a -w option to encode an arbitrary COM file in an ASCII-only format. There is also a -e option, to recover the original binary COM file. Later, this feature was moved to a separate NETRUN utility.

ASCII-encoded files are normally wrapped in some plain text instructions, telling you to use a text editor to save the payload data to a .COM file. Most versions have a -z option to omit the wrapper, producing a file that can be executed directly (though you may have to rename it to end in ".COM").

Versions 2.00+ include an NPX2GIF utility that converts an executable image file back to a GIF file.

Identification

Note that some versions, notably 2.00 and 3.10, have not been located for evaluation. We'll assume the text wrapper has been deleted or suppressed, though robust identification would have to account for it.

Binary-encoded GIF→COM files for all versions apparently start with bytes f6 06 2f 01 ff 74 ?? ba 15 01 b4 09 cd 21 b4 07.

Version 1.x ASCII-encoded GIF→COM (NPX) files, without the wrapper, start with "NETPIC.COM" (which apparently is valid x86 machine code).

Version 3.02 ASCII-encoded GIF→COM (NPX) files, without the wrapper, start with "ZRX-sm-sm-Z". The string "NETPIC_COPYRIGHT_1995_BY_JIM_TUCKER" appears in the file, at offset 462 by default, or offset 396 for 3→4 encoding (-3 option).

Version 3.20-4.20 ASCII-encoded GIF→COM (NPX) files, without the wrapper, start with "XPPPYZIQD". This does not distinguish them from NETSEND and some NETRUN files. Files made by NETPIC apparently have "NETPIC" at offset 47.

The ASCII-encoded arbitrary COM files from v1.0's -w option, without the wrapper, start with "COM-PRG.COM". This does not distinguish them from older NETRUN files. Files made by NETPIC have "NETPIC" at offset 520.

Software

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