A86 (software)
| Developer(s) | Eric Isaacson |
|---|---|
| Stable release |
4.05 / 2006
|
| Operating system | MS-DOS |
| Platform | x86 |
| Type | Assembler |
| License | Proprietary |
| Website | eji |
A86 is computer software, a compact commercial assembler developed for the Intel x86 family of microprocessors by Eric Isaacson. It was first made available as shareware in the 1980s.
The assembler is contained in one 32K executable and can directly produce an MS-DOS compatible COM file or an object file for use with a standard linker. A86 uses a slightly simpler syntax for source code and does not require the extensive use of directives as do contemporaries such as the Microsoft Macro Assembler (MASM). Isaacson claims that A86 can assemble 100,000 lines of source per second on a Pentium II or better. It comes with a debugger, D86.
A86/D86 targets 16-bit x86 platforms. Isaacson added 32-bit support in the mid 1990s in the form of A386 and D386. These were not distributed as shareware, but were provided to users who registered A86.
Isaacson never ported the A86 family of products to Windows, though it is possible to use the object files created by A386 with a Windows linker. The assembler cannot be used to create 64-bit code.
Any label that is one letter followed by one or more digits is local, and can be redefined as needed, with each definition replacing the prior. Isaacson recommends using L1 through L9 for normal code and M1 through M9 in macros. Branches to local labels are assumed to be backward, but a forward branch can be specified by prefixing the label reference with the greater than symbol (e.g., >L2).
Numbers starting with a zero are hexadecimal, such as 00FF, instead of using a custom prefix.
Multiple registers can be pushed or popped on the same source line. push eax, edx, ebp generates one instruction for each of the three operands.
The assembler automatically embeds a "fingerprint" into the generated code through a particular choice of functionally equivalent instruction encodings. This makes it possible to tell if code was assembled with A86, and also to distinguish between registered and unregistered versions of the assembler, although access to the source code is required.
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