1. Computer Systems – Memory & the 3 box Model

2. Blog It!
Make sure that you have notes on everything we have discussed so far today and post these to your blog.

3. Starter Can you match the computer parts with their names? Fan
CPU – Central Processing Unit
RAM
Hard disk
Video card
PSU – Power Supply Unit

4. Main Memory
Main memory (RAM) consists of a series of memory locations, all of which can be accessed in any order by the processor, with the location having no bearing on the speed of access.
Each memory location can hold instructions or data.
The total number of bytes in main memory is referred to as the computer’s memory size.

5. Memory Size over Time
“640K ought to be enough for anybody” – Bill Gates
2000 – A PC with 64 or 128MB of RAM was standard, costing around £1000 including bundled software.
2015 -

6. Concept vs. Reality

7. The Three-Box Model

8. Stored program concept
A program must be resident in the main memory.
Machine code instructions are fetched one at a time and executed in order in the processor.
Instructions can be Arithmetic as well as Logical operations e.g. (ADD, SUBTRACT, AND and OR)
Instructions stored as binary, same as data. ( )
Therefore, in a von Neumann computer, a single memory location can store values which are data or instructions.
= data or
= instruction to ADD

9. Von Neumann Stored Program Computer
This computer is a serial machine – data AND instructions can be stored in the same Memory location and acted upon sequentially.
Addresses
Processor
Main Memory
System BUS
Data & Instruction