The Analytical Engine Online: Hardware

Computer hardware implements the binary language of Module 6 using digital circuits. In this module, we provide you with a program called Logg-O, for designing and experimenting with simple digital logic circuits. It will be used to demonstrate the utility of logic for carrying out computations.

Lab 7.1: Leggo my Logg-O

Lab 7.2: Bill's Gates

Lab 7.3: Towards Arithmetic

Lab 7.4: Towards Memory

Lab 7.5: An Architect's View

Explain why computers only understand binary languages
Show how the circuits of a computer are constructed
Discuss the hierarchical complexity of computer hardware
See how simple circuits, combined in complex ways, can implement a model computer
Explore the design of a small but complete microprocessor

Module Quiz

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References

The Module 6 labs demonstrated both the feasibility and the necessity of using a binary language¹ as a means for communicating with a computer. Why, though, do computers understand only such simple languages²? Because both binary numbers and a computer's hardware are essentially two-valued systems and, as such, can be used to represent and implement boolean logic³.
¹pp. 203–205, 243, 273–274, 282
²pp. 210, 216
³pp. 160, 238–241, 311

In the text part of this module, we see how the computer, at the lowest level, is a physical embodiment of the rules of logic. Starting with simple switches⁴, we build increasingly complex hardware - using switches to construct simple circuits, then using these to construct a hierarchy of more complicated circuits, or chips, and finally connecting these circuits to build a computer⁵. By the end of this module, you will have constructed, on paper at least, a simple but fully functioning computer with nearly all the important features of real machines.
⁴pp. 235, 262
⁵pp. 7, 257

The metaphor for this module is the light switch, a box with a small lever and two wires attached. Flip the lever down and no current can flow through the wires; flip it up and current can pass. We won't worry about how things work inside the switch because for our purposes it is sufficient to assume that it does what we want. All we need to do to accomplish most of the mechanized computations we've described is remove the lever from the switch and replace it with an extra wire that can be used to control the switch. With enough of these switches, connected in the right way, we can implement any computer operation we want.

	Print References
The Module 6 labs demonstrated both the feasibility and the necessity of using a binary language¹ as a means for communicating with a computer. Why, though, do computers understand only such simple languages²? Because both binary numbers and a computer's hardware are essentially two-valued systems and, as such, can be used to represent and implement boolean logic³.	¹pp. 203–205, 243, 273–274, 282 ²pp. 210, 216 ³pp. 160, 238–241, 311
In the text part of this module, we see how the computer, at the lowest level, is a physical embodiment of the rules of logic. Starting with simple switches⁴, we build increasingly complex hardware - using switches to construct simple circuits, then using these to construct a hierarchy of more complicated circuits, or chips, and finally connecting these circuits to build a computer⁵. By the end of this module, you will have constructed, on paper at least, a simple but fully functioning computer with nearly all the important features of real machines.	⁴pp. 235, 262 ⁵pp. 7, 257
The metaphor for this module is the light switch, a box with a small lever and two wires attached. Flip the lever down and no current can flow through the wires; flip it up and current can pass. We won't worry about how things work inside the switch because for our purposes it is sufficient to assume that it does what we want. All we need to do to accomplish most of the mechanized computations we've described is remove the lever from the switch and replace it with an extra wire that can be used to control the switch. With enough of these switches, connected in the right way, we can implement any computer operation we want.

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