Microprogrammed computer simulator tools

A versatile microassembler and assembler program is described that was developed to facilitate the preparation of symbolic microprograms and assembly language programs for use with the microprogrammable computer simulator ET (educational tool) previously reported by the authors (see ibid., vol.E-30, p.135, Aug. 1987). The microassembler program takes as input a microprogram source file written in symbolic form and produces files ready for loading into the simulator´s control ROM and address ROM. In addition, a file containing the mnemonics and corresponding op-codes of each instruction in the instruction set of the machine being simulated by the microprogram is created. The assembler program uses this file together with a user-written symbolic assembly language source program and produces a file containing machine language object code ready for loading into the simulator´s RAM. Both the microassembler and the assembler also produce list files that may be examined by the user. Students of computer architecture indicate that use of these tools, in conjunction with the ET simulator, greatly simplifies the task of learning how microprogrammed computers function