Such astack machine architecture is inherently simpler since all instructions operate on the top-most stack entries.
One result of the stack architecture is an overall smaller instruction set, allowing a smaller and faster instruction decode unit with overall faster operation of individual instructions.
Separate from the stack definition of a MISC architecture, is the MISC architecture being defined by the number of instructions supported.
Typically a minimal instruction set computer is viewed as having 32 or fewer instructions,[1][2][3] where NOP, RESET, andCPUID type instructions are usually not counted by consensus due to their fundamental nature.
32 instructions is viewed as the highest allowable number of instructions for a MISC[by whom?], though 16 or 8 instructions are closer to what is meant by "Minimal Instructions".
TheIBM SSEC had the ability to treat instructions as data, and was publicly demonstrated on January 27, 1948. This ability was claimed in a US patent issued April 28, 1953.[6] However, it was partly electromechanical, not fully electronic. In practice, instructions were read from paper tape due to its limited memory.[7]
TheManchester Baby, by theVictoria University of Manchester, was the first fully electronic computer to run a stored program. It ran a factoring program for 52 minutes on June 21, 1948, after running a simple division program and a program to show that two numbers wererelatively prime.
The Electronic Numerical Integrator and Computer (ENIAC) was modified to run as a primitive read-only stored-program computer (using the Function Tables for programread-only memory (ROM) and was demonstrated as such on September 16, 1948, running a program byAdele Goldstine for von Neumann.
The Binary Automatic Computer (BINAC) ran some test programs in February, March, and April 1949, although was not completed until September 1949.
TheManchester Mark 1 developed from the Baby project. An intermediate version of the Mark 1 was available to run programs in April 1949, but was not completed until October 1949.
The Electronic Discrete Variable Automatic Computer (EDVAC) was delivered in August 1949, but it had problems that kept it from being put into regular operation until 1951.
The Commonwealth Scientific and Industrial Research Automatic Computer (CSIRAC, formerly CSIR Mk I) ran its first program in November 1949.
The Standards Eastern Automatic Computer (SEAC) was demonstrated in April 1950.
ThePilot ACE ran its first program on May 10, 1950 and was demonstrated in December 1950.
The Standards Western Automatic Computer (SWAC) was completed in July 1950.
TheWhirlwind was completed in December 1950 and was in actual use in April 1951.
The firstERA Atlas (later the commercial ERA 1101/UNIVAC 1101) was installed in December 1950.
The disadvantage of a MISC is that instructions tend to have more sequential dependencies, reducing overallinstruction-level parallelism.
MISC architectures have much in common with some features of someprogramming languages such asForth's use of the stack, and theJava virtual machine. Both are weak in providing fullinstruction-level parallelism. However, one could employmacro-op fusion as a means of executing common instruction phrases as individual steps (e.g., ADD,FETCH to perform a single indexed memory read).
Probably the most commercially successful MISC was the original INMOStransputer architecture that had nofloating-point unit. However, many8-bitmicrocontrollers, for embedded computer applications, qualify as MISC.
^US patent 5481743A, Baxter, Michael A., "Minimal instruction set computer architecture and multiple instruction issue method", published 1996-01-02, issued 1996-01-02, assigned to Apple
^Halverson, Richard Jr.; Lew, Art (1995).An FPGA-Based Minimal Instruction Set Computer (Technical report). Information and Computer Sciences Department, University of Hawai. p. 23. ICS-TR-94-28.
^Kong, J.H.; Ang, L.-M.; Seng, K.P. (2010). "Minimal Instruction Set AES Processor using Harvard Architecture".2010 3rd International Conference on Computer Science and Information Technology. pp. 65–69.doi:10.1109/ICCSIT.2010.5564522.ISBN978-1-4244-5540-9.
^Robertson, James E. (1955). Illiac Design Techniques: report number UIUCDCS-R-1955-146 (Report).Urbana–Champaign, Illinois: Digital Computer Laboratory, University of Illinois at Urbana–Champaign.
^US patent 2636672, Hamilton, Francis E.; Hughes, Ernest S. Jr. & Rowley, Russell A. et al., "Selective Sequence Electronic Calculator", issued 1953-04-28, assigned to IBM
