PALASM

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Description of a 4-bit synchronous counter in PALASM

The name PALASM stands for one of the first hardware description languages that was used in digital technology in the early 1980s to program the first programmable logic circuits available on the market , the so-called Programmable Array Logic (PAL).

PALASM was developed by John Birkner , then employed by Monolithic Memories Inc. (MMI), in 1982. PALs were developed a few years earlier and with the help of PALASM, MMI gave users the easier option of configuring these then novel logic circuits for their own applications. In addition to the Advanced Boolean Equation Language (ABEL), PALASM is one of the first hardware description languages.

The first PALASM compiler was programmed in Fortran IV on an IBM System 370/168 . The source code was made available free of charge by MMI. In later years PALASM was ported to other contemporary computer systems, including PDP-11 from the Digital Equipment Corporation (DEC) and HP2100 from the Hewlett-Packard 1000 series .

In PALASM, Boolean expressions express logic levels at the connection pins of a PAL. The compilter translates these expressions into a so-called English fuse map which can then be programmed into a PAL using additional auxiliary programs. The fuse map is based on the type of implementation that the one-time programming of the logical interconnections in a PAL is implemented using a large number of small electrical fuses . As part of the programming process, these fuse elements are specifically burned out in order to achieve the desired circuit function.

Towards the end of the 1980s, PALASM lost its importance, triggered by the increased replacement of PALs by the more powerful Complex Programmable Logic Devices (CPLDs), and more general and more extensive hardware description languages ​​such as VHDL or Verilog were increasingly used in the development process.

Web links

Individual evidence

  1. MMI PALASM. Retrieved January 26, 2016 .