The Analytical Engine


In these pages, I've used Babbage's own terminology for components and operations in the Analytical Engine. The following table gives the equivalents in contemporary computer terminology.

Babbage's Analytical Engine Contemporary Computer
Accidental sign Sign bit
Analyst Programmer
Attendant Operator
Axis Buffer register
Barrel Microcode
Card Instruction
Card, Operation Arithmetic instruction
Card, Combinatorial Instruction, control transfer (test / jump)
Card, Number Instruction, load immediate
Card, Variable Instruction, load / store
Carriage Carry propagation
Curve Drawing Apparatus Plotter
Column (of Rack) Memory (RAM) cell
Cycle Loop
Mill Arithmetic and Logical Unit (ALU)
Rack (of Columns) Random Access Memory (RAM)
Run up Overflow or Sign Bit Condition Code
Stepping down Right shift
Stepping up Left shift
Store Memory (RAM) Array
Turn of the Handle Clock cycle


Table of Contents

by John Walker