quartz/content/notes/04-computer-architecture.md
2022-07-23 23:14:14 +12:00

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---
title: "04-computer-architecture"
aliases:
tags:
- cosc204
---
- tristate buffer [slide](https://i.imgur.com/2Kb419g.png)
- ![memory write](https://i.imgur.com/PExnbFm.png) [circuit simulator](https://tinyurl.com/2bmqovqz)
- ![memory read](https://i.imgur.com/GZwxuaA.png)
# Bus
- data bus
- address bus
- control bus
- conmmunicate between parts of the computer
- only one transmitter at a time
- only addressed device can respond
- 2 levels
- internal
- external
# Memory
- memory size is dependent on bus size
- 2n bytes for n-lines on the address bus
- 2^8=256B, 2^16=64KB, 2^32=4GB, 2^64=16EB
- flip flops are grouped into bytes (or larger)
- each byte has an address
- to write
- present the address and the data
- tell chip to write
- to read
- present the address
- tell the chip to read
- look at the data
## Static RAM (SRAM)
- memory made from flip flops is called static RAM
- used mostly in CPU cache
- or anywhere where only a small amount is needed
- expensive
## Dynamic RAM (DRAM)
- made from capacitors
- used where large amount of RAM is needed
- slower than SRAM
- inexpensive
## Non-Volatile Memory
- often called ROM (read only memory)
- can also be called PROM, EPROM, EEPROM, FLASH
- flash
- uses floating-gate flash cells, not quite a transistor
# ALU
![](https://i.imgur.com/wLJhTSG.png)
- performs arithmetic
- add, subtract, etc.
- logical operations
- and, or, shift, etc
- subunits
- lofical operations
- addition
- multiplication and dividion
- shifting
- comparison
- logical tests (if, >0, <0, =0, <=0, etc)
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