There is an associated Watcom disassembler, wdis. The assembler does not have listing facilities; instead the use of wdis for generating listings is recommended. wdis can read OMF, COFF and ELF object files and PE and ELF executables. It supports 16-bit and 32-bit x86 instruction set including MMX, 3DNow!, SSE, SSE2, and SSE3. Support for PowerPC, Alpha AXP, MIPS, and SPARC V8 instruction sets is also built in.
WASM forks
JWasm
JWasm is a fork of Wasm originated by Japheth with following features:
Native support for output formats Intel OMF, MS Coff, Elf, Bin and DOS MZ.
Precompiled JWasm binaries are available for DOS, Windows and Linux. For OS/2 and FreeBSD, makefiles are supplied.
JWasm is written in C. The source is portable and has successfully been tested with Open Watcom, MS VC, GCC and more.
On Windows, JWasm can be used with both Win32Inc and Masm32. Since v2.01, it will also work with Sven B. Schreiber's SBS WALK32 Win32 Assembly Language Kit
C header files can be converted to include files for JWasm with Japheth's own dedicated h2incX.
Fully supports Microsoft macro assembler 6 syntax, all MASM 8 instructions sets.
Japheth ceased development of JWASM in January 2014 with version 2.12pre, but others on the Masm32 forum picked up where Japheth left off.
HJWasm
HJWasm, adding the prefix H in reference to Masm32 forum member Habran who started off this second WASM development continuation. Version 2.13pre was originally announced in 2016. New features include:
Instructions:
Registers: RIP, ZMM registers added in 2.13.
OO language extension added in 2.25.
HASM
UASM is a renamed version of HJWASM, starting in version 2.33. The name was used following a MASM Forum discussion thread that originally proposed a replacement name. The name HASM was proposed by forum member habran in Reply #6, and was finalized at the end of discussion thread at Reply #33. No known features are added in HASM's release cycle.
UASM
The name was actually used in version 2.33 at Terraspace ltd's product page, but it was only announced in version 2.34. Changes to HJWASM includes:
Instruction sets: RDPID added in 2.38.
Addressing modes: 64bit absolute immediate
Identified types
Console colour coding: Added for Windows, OSX and Linux in 2.43.1 /.2.
Function calling: C-style function calling added in 2.46.
