Bit-Slice Design: Controllers and ALUs

by Donnamaie E. White

Copyright © 1996, 2001, 2002 Donnamaie E. White

 
 

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

 

 

 

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)

For information about this file or to report problems in its use email dew@Donnamaie.com

Copyright © September 1996, 1999, 2001, 2002 Donnamaie E. White White Enterprises

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