Data General Corporation MicroNOVA MP/100

    Data General's MicroNOVA MP/100 is an example of their second- generation microprocessor NOVA implementations. The CPU is implemented on a single VLSI (Very Large Scale Integration) IC capable of executing the basic NOVA instruction set with a few additional op-codes. As in the "standard" NOVA architecture, there are four accumulators, the program counter, the carry bit, a basic maximum of 32 kW of memory, and 64 I/O devices. The mN602 MicroNOVA processor executes an extended version of the NOVA instruction set; the extensions include integer multiply/divide instructions and stack handling mechanisms.

    The front panel, so familiar to Nova "heads", is replaced by a "soft front panel" in the MP/100 machine. This uses the console terminal as a "console simulator" (similar in concept to DEC's pdp11 ODT) as the "front panel". All usual panel operations are available via keyboard commands; breakpointing operations from the "console" are an added bonus in this system (a nice touch for those of us who write buggy programs).

    The bus structures of the MicroNOVA differ radically from that of the "classic" NOVA systems in that the new structures derive their basis from microprocessor design using serial and multiplexed bidirectional architectures rather than dedicated unidirectional parallel lines. The memory bus is sixteen bits wide with a 15 bit address space (NOVA standard), but the memory address lines share the same data paths as the memory data lines. The I/O bus (including the NOVA data channel) is implemented as a serial bus structure built up around a pair of differential lines, each of which carry one byte plus a single control bit per I/O transfer.

    This particular machine came complete with the architectural maximum of 32 kW core memory (actually DRAM (Dynamic Random Access Memory)) implemented as 32 Intel 2117-3 RAM chips on a single board. Refresh is handled by the CPU module. Also included as peripherals on this machine are a second RS-232 serial line, a line printer controller, and a digital to analogue converter board.

    Raw instruction execution speed of the MP/100 is about one third that of my Nova 840 and about half that of the Nova 1200 class .

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