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The ROMP or Research OPD Microprocessor was a RISC microprocessor designed by IBM in the late 1970s. It is also known in some circles as 032. "OPD" stands for "Office Products Division", the division of IBM which originated the processor. The ROMP saw first silicon in 1981, and was originally developed for office equipment and small computers.[1] It was intended as a follow-on to a mid-1970s processor called the "OPD Mini Processor", which was used in text editing systems such as the IBM Office System/6.[citation needed] ROMP originally was shipped in the IBM RT PC line, announced in 1986, and was later used in an IBM laser printer. For a time the IBM RT PC was planned to be a personal computer, with ROMP replacing the Intel 8088. However, the software was targeted more towards engineering workstations.

Introducedearly 1980s
EncodingVariable (2 or 4 bytes long)
BranchingCondition code
Page size4 KB pages
General purpose16× 32-bit

The original ROMP had a 24-bit Reduced Instruction Set Computer (RISC) architecture developed by IBM, but the instruction set was changed to 32 bits a few years into the development.[2] It had sixteen 32-bit general purpose registers and used 32-bit addresses and data paths. The microprocessor was controlled by 118 simple two- and four-byte instructions.[3] Internal processor organization enabled the CPU to execute most register-to-register instructions in a single cycle. IBM also developed a companion memory management unit (MMU) IC, which provided the ROMP with a 40-bit virtual address space and address translation facilities.

The ROMP and its MMU were originally implemented in an IBM 2 μm silicon-gate NMOS technology with two levels of metal interconnect. μm[4][5] The ROMP consists of 45,000 transistors and is 7.65 × 7.65 mm large (58.52 mm2), while the MMU consists of 61,500 transistors and is 9.02 × 9.02 mm large (81.36 mm2). Both are packaged in 135-pin ceramic pin grid arrays.[5]

The architectural work started in late spring of 1977, as a spin-off of the T.J. Watson Research 801 processor (hence the "Research" in the acronym). Most of the architectural changes were for cost reductions, such as adding 16-bit instructions for byte-efficiency.

The first chips were ready in early 1981, making ROMP the first industrial RISC. The processor was revealed at the International Solid-State Circuits Conference in 1984[5] ROMP first appeared in a commercial product as the processor for the IBM RT PC workstation, which was introduced in 1986. To provide examples for RT PC production, volume production of the ROMP and its MMU began in 1985.[5] The delay between the completion of the ROMP design, and introduction of the RT PC was caused by overly ambitious software plans for the RT PC and its operating system (OS). This OS virtualized the hardware and could host multiple other operating systems. This technology, called virtualization, while commonplace in mainframe systems, only began to gain traction in smaller systems in the 21st century.


  1. ^ Hester, P.D.; Simpson, Richard O.; Chang, Albert. "The IBM RT PC ROMP and Memory Management Unit Architecture". In Waters, Frank. The IBM RT Personal Computer Technology, Form No. SA23-1057 (PDF). p. 48.
  2. ^ Waldecker, D.E.; Woon, P.Y. "ROMP/MMU Technology Introduction". In Waters, Frank. The IBM RT Personal Computer Technology, Form No. SA23-1057 (PDF). p. 44.
  3. ^ Furber, Stephen (1989). VLSI RISC Architecture and Organization. CRC Press. pp. 106–109.
  4. ^ Waters, Frank (ed.). The IBM RT Personal Computer Technology. p. 8.
  5. ^ a b c d Bambrick, Richard (27 January 1986). "IBM's New RISC Processor Based on 10-Year Project". Electronic News.

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