The MC88100 is a

microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circu ...

developed by

Motorola Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois, United States. After having lost $4.3 billion from 2007 to 2009, the company split into two independent public companies, Motorola ...

that implemented 88000

RISC In computer engineering, a reduced instruction set computer (RISC) is a computer designed to simplify the individual instructions given to the computer to accomplish tasks. Compared to the instructions given to a complex instruction set compu ...

instruction set architecture In computer science, an instruction set architecture (ISA), also called computer architecture, is an abstract model of a computer. A device that executes instructions described by that ISA, such as a central processing unit (CPU), is called an ...

. Announced in 1988, the MC88100 was the first 88000 implementation. It was succeeded by the MC88110 in the early 1990s. The microprocessor has separate pipelined integer, floating-point add, floating-point multiply, and load/store execution units and dispatches a single instruction (at most) per clock cycle. The separate MC88200 integrated circuit optionally add level 1 cache and a paged

memory management unit A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit having all memory references passed through itself, primarily performing the translation of virtual memory addresses to physical ...

. An MC88100 system typically used two of these devices for instructions and data; additional MC88200s could be added to increase the size of the caches. This partitioned scheme was chosen to provide system flexibility, the amount of cache could be varied depending on the price point. In practice, these additional chips required more space on the circuit board and the buses between the MC88200s and MC88100 added complexity and cost. The MC88100 contained 165,000 transistors and the MC88200 750,000 transistors. Both were fabricated by Motorola in its 1.5 μm

complementary metal–oxide–semiconductor Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss", ) is a type of metal–oxide–semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOS ...

process. The MC88100 was ultimately commercially unsuccessful. This was due to a number of reasons, including requirement of MC88200s, but was mostly due to Motorola being a vendor of the highly successful

68000 The Motorola 68000 (sometimes shortened to Motorola 68k or m68k and usually pronounced "sixty-eight-thousand") is a 16/32-bit complex instruction set computer (CISC) microprocessor, introduced in 1979 by Motorola Semiconductor Products Secto ...

family. As the 68000 division viewed the 88000 as a competitor, they forced the MC88100 to be priced unacceptably high for a volume part. The part did find use in the high-end embedded market, in Motorola's own computers, and in large computers from companies such as

Data General Data General Corporation was one of the first minicomputer firms of the late 1960s. Three of the four founders were former employees of Digital Equipment Corporation (DEC). Their first product, 1969's Data General Nova, was a 16-bit minicompu ...

and the

Unisys Unisys Corporation is an American multinational information technology (IT) services and consulting company headquartered in Blue Bell, Pennsylvania. It provides digital workplace solutions, cloud, applications, and infrastructure solutions ...

S-8400 Unix Servers.

Design

Programming model and register set

The programming model and register set of the MC88100 is remarkably similar to

DLX The DLX (pronounced "Deluxe") is a RISC processor architecture designed by John L. Hennessy and David A. Patterson, the principal designers of the Stanford MIPS and the Berkeley RISC designs (respectively), the two benchmark examples of RISC desi ...

(and by extension,

RISC-V RISC-V (pronounced "risk-five" where five refers to the number of generations of RISC architecture that were developed at the University of California, Berkeley since 1981) is an open standard instruction set architecture (ISA) based on establi ...

) based CPUs, with 32 General-purpose registers (31 writable) and 51 instructions capable of accessing any of the 32 general-purpose registers at any time.

Registers

The MC88100 is equipped with a total of 64 user-accessible registers, 32 of them being

Control registers A control register is a processor register which changes or controls the general behavior of a CPU or other digital device. Common tasks performed by control registers include interrupt control, switching the addressing mode, paging control, and ...

, and can access up to 6 registers (4 read, 2 write) simultaneously. The actual usage of GPR is not enforced by the processor for every register except R1, which is used as a return address.

References

* * * * {{DEFAULTSORT:Mc88100 Motorola microprocessors Superscalar microprocessors Motorola 88100