Preface
Table of Contents
1. Introduction
2. Simple Controllers
3. Adding Programming
Support to the Controller
4. Refining the CCU
5. Evolution of the
ALU
6. The ALU and Basic
Arithmetic
7. Tying the System
Together
Glossary
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Last Edit September 23, 1996; July 7, 2001
Glossary
- ACC
- accumulator register
- ALU
- arithmetic logic unit
- CC
- condition code test input on Am2910
- CCU
- computer control unit -- contains ROM or PROM or WCS; the microsequencer;
the IR; the pipeline (microinstruction) register; condition code MUX
- Cf
- minumum cycle width
- Cp, CLK
- clock signal (rising edge)
- Cp
- microcycle width; pulse width; clock signal time between two rising
or active-signal edges
- CPU
- cnetral processing unit
- cycle time
- when microprogramming, usually refers to one clock cycle; one microcycle
or clock cycle being required to execute one microinstruction where
a microinstruction is equivalent to a microstep
- DIP
- dual in-line pin package (other packages exist but are not as common
for the bit-slice)
- DMA
- direct memory access
- EPAC
- electrically programmable analog circuit
- EPROM
- erasable PROM
- EEPROM
-
- firmware
- program which controls the system,; usually stored in PROM/ROM memory
but not restricted to read-only memory
- FIS
- fixed-instruction set
- FPLA
- field programmable logic array
- Hex
- hexadecimal
- I/O
- input/output
-
-
- IP
- Intellectual Property - used to refer to a pre-designed functional
block that can be treated as a hard or soft macro
-
-
- IR
- instruction register
- LIFO
- last in; first out stack operation
- LSB
- least significant bit
- LSI
- large-scale integration (200-1000 gates per die); the name of a company
- LSS
- least significant slice (as in bit-slice)
- macroinstruction
- a machine-level instruction
- MAR
- memory (main memory) address register
- microinstruction
- an instruction that actually controls the hardware activity (binary
bit-level)
- microprocessor
- one chip that contains control logic, registers and an ALU; the complexity
of what is called a microprocessor has expanded beyond this primitive
level
- microprogrammable
- the user may alter the control program
- microprogrammed
- the user may not alter the control program
- microroutine
- sufficient microinstructions to carry out one machine-level instruction
- MOS
- metal-oxide-silicon technology
- MSB
- most significant bit
- MSI
- medium-scale integration
- MSS
- most significant slice (in bit-slice)
- MUX
- multiplexer; a select-one-of-n device
- opcode
- operation code; part of a machine-level instruction which specifies
the function to be performed
- operand
- data elements that will be operated on by the operation code
- PC
- program counter (main memory; machine programmed); more common definition
is a personnal computer
- µPC
- microprogrammed counter register; register which contains the address
of the next microinstruction to be executed; more common definition
is microprocessor
- PCB; PC Board
- printed circuit board
- PLA
- programmable logic array
- PROM
- programmable reads-only memory (user-programmed) [used in text to
represent EPROMS and other variations of the basic PROM concept]
- RALU
- ALU with registers (scratchpad)
- RAM
- read-write memory (volatile)
- ROM
- read-only memory (factory programmed) (non-volatile)
- RTL
- resistor-transistor logic (original definition); register-transfer
level (newer meaning)
- scratchpad registers
- local storage for user, system programs
- SSI
- small scale integration
- I(ALU execution)
- maximum delay of ALU from instruction lines stable to ALU output useable
- t(counter clock to output)
- maximum delay clock edge received by counter until output usable
- ti (max)
- worst-case maximum value of time ti
- ti(min)
- worst-case minimum value of time ti
- t(pipeline click to output)
- maximum delay clock edge received by pipeline register until output
usable
- t(PROM read access)
- maximum time delay from address lines stable until PROM output stable
- TOS
- top of the stack
- TTL
- transistor-transistor logic
-
- VLSI
- very large scale integration such as ASICs (1000-100,000); the industry
got a little crazy after this level and tried all sorts of acronyms
to represent the really dense stuff
- WCS
- writable control store; control memory built from read-write memory
and therefore alterable (for microprogrammable systems)
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