1750A

The 1750A is not a particular computer, but a family of compatible computers that implement the instruction set described by the military standard document MIL-STD-1750A, (1980). The computers have been constructed by many methods, by a wide variety of companies. Traditionally, 1750s run aircraft, missiles or parts thereof. They are usually programmed in JOVIAL, a high-level programming language similar to Algol.

The U.S. Air Force defined the standard in order to reduce the costs of software and computer systems for aircraft and missiles.

The 1750 usually has a 16-bit bus, and 2¹⁶ 16-bit words of memory. The standard defines an optional memory management unit that allows 2²⁰ 16-bit words of memory using 512 page mapping registers (in the I/O space), defining separate instruction and data spaces, and keyed memory access control.

Most instructions are 16 bits, although some have a 16-bit extension. The standard computer has 16 general purpose 16-bit registers. Registers 1 through 16 can be used as index registers. Registers 13 through 16 can be used as base registers. The computer has instructions for 16, and 32-bit binary arithmetic, as well as 32 and 48 bit floating point. I/O is generally via the I/O instructions (XIO and VIO), which have a separate 2¹⁶ 16-bit word address space and may have a specialized bus.

External links

• Specification and vendor information