Overview of Microprogramming
Reference: Bell, Siewiorek, Newell: Computer Principles: Structures and Examples,
Part II, Section I, Microprogram-Based Processors. See especially chapters 11 and 13.
Relationship to FSM equations
- Implementation of next state and output functions as truth tables in ROM
- Variation on the theme to reduce storage required for next state function
Form of microoperations
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Horizontal
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Vertical
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Diagonal
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Vertical with Nanostore
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Conventional microcontrollers
- Current state = Microaddress Register (also called Micro-PC)
- Next state logic is microsequencing logic of microcontroller
- Control branch logic is selected by branching specifications (opcode) of Control Branch Micro-operations
Control branch Micro-operations
- Incrementing mPC and WAIT
for asynchronous waits, or with counter for one-step loops (e.g., multiply and divide)
- Conditional branch
- Three way branching
with counters for timing or iteration
- Multiway (CASE) branching
- Procedure calling (Push/Pop)
Copyright 1995, Ben M. Huey
Copying this document without the permission of the author is prohibited
and a violation of international copyright laws.
Rev. 9/21/95 B. Huey