- Author
- Mark Smotherman
- Published
- September 2026
- Kind
- Long web history page with worked example, appendices and references
- Original
- people.computing.clemson.edu/~mark/uprog.html
- Subject
- Systems and hardware
What it is
Mark Smotherman wrote a long web page on the history of microprogramming. It defines the technique with a worked four-instruction example. It then traces the history from the late 1940s to recent proposals. Appendices cover early hardwired control designs.
What it says
- Maurice Wilkes published the first microprogramming paper in 1951, after visiting the MIT Whirlwind.
- The Cambridge group tested the first microprogrammed computer in 1957, using a magnetic core matrix.
- All but two of the initial IBM System/360 models were microprogrammed.
- Larry Moss named emulation for microcode that ran older IBM programs on System/360.
- By the late 1960s microprogramming was the usual choice. The fastest and simplest machines were exceptions.
- RISC chips of the 1980s such as SPARC and MIPS were hardwired.
- Microcode is still used in x86-compatible chips, with a small RAM for patches.
What evidence it gives
The page gives a worked example with control signal tables. It adds a table comparing four IBM System/360 models. It cites many papers, books, patents and manuals. It quotes Wilkes's memoirs on how the idea formed.
Interests and limits
This is a single-author survey on a university page, last updated in September 2026. It is a history and argues little. Dates and specifications rest on the cited sources, which were not checked. The figures and diagrams are images and were not viewed. The text and reference list were read.