Turbo Assembler (TASM)

ern0 31/07/2026 09:44

TASM was extremely fast, just like other Borland compilers, e.g. Turbo Pascal. Of course, an assembler is significantly simpler than a modern high-level language compiler, but TASM stood out as the first assembler to perform compilation in a single pass. While processing the source code, if it encountered an unresolved reference - e.g. a forward jump, or some data/BSS declared later - it would generate a placeholder address. Later, when the compilation reached the referenced target, it would go back and complete those placeholders. There was only a few of failure cases, say, when a forward relative jump exceeded the range, otherwise, it worked quite well.

ern0 31/07/2026 09:36

"Turbo Assembler was favored for its speed and compatibility with the popular x86 architecture, which was widely used in personal computers of the time" - not exactly. It's not wrong, but isn't right either, let me explain it.

1. The x86 processor family owed its popularity mainly not to its own merits, but to IBM's decision to use it in their personal computer, which became not only simply popular, but a de-facto standard.

2. "Compatible" makes it sound like it just happened to work, or the PC was one of the many platforms it was running on, which isn't right. It was explicitly an x86 assembler, made for the PC from the start, running under MS-DOS, with the main intent to creating programs for MS-DOS.