The Flat Assembler is a fast and efficient self-assembling 80x86 assembler.

Flat Assembler supports all 8086-80486/Pentium instructions with MMX, SSE, SSE2, SSE3 and 3DNow! extensions and x86-64 (both AMD64 and EM64T) instructions and it can generate output in binary.

It includes the powerful but easy to use macroinstruction support and does multiple passes to optimize the instruction codes for size.

The Flat Assembler is self-compilable and the full source code is included.

The only difference between the various flat assembler packages is the operating system on which they can be executed.

From given source each version will generate exactly the same output file, so with each of the following releases you can compile programs for any operating system.

What's New in This Release: [ read full changelog ]

· Fixed a bug which caused instructions from JCXZ/LOOP family to be incorrectly assembled when requiring 67h prefix and provided with "$" operand.
· Definition of macro with the same name as one of the preprocessor's directives is no longer allowed.
· Fixed REPT directive to check out validity of its parameters even when the count is zero.
· Fixed VMREAD/VMWRITE syntax in the USE64 mode.
· Corrected MZ header generation and handling for the case when the last page of executable contains the round 512 bytes