1. Chapter 0 Introduction to Computing

2. Section 0.1 Numbering and Coding Systems

3. Outlines of Section 0.1 Decimal and binary number systems
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Outlines of Section 0.1
Decimal and binary number systems
Converting between decimal to binary
Hexadecimal system
Converting between binary and hex
Counting in bases 10, 2, and 16
Addition and subtraction of hex number
ASCII codes
Please review the items if you have forgotten them.
A printer is an example of embedded system since the processor inside it performs one task only.

4. Section 0.2 Digital Primer

5. Outlines of Section 0.2 Binary Logic
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Outlines of Section 0.2
Binary Logic
Logic Gates - AND, OR, NOT, XOR, NAND, NOR
Logic design using gates
Decoders
Flip-flops
Please review the items if you have forgotten them.
A printer is an example of embedded system since the processor inside it performs one task only.

6. Section 0.3 Inside the Computer

7. Important Terminology
Bit
Nibble (4 bits)
Byte (8 bits)
Word (32 bits)
KB (kilobyte)＝210 bytes
MB (megabyte)＝220 bytes
GB (gigabyte)＝230 bytes
TB (terabyte)＝210 bytes

8. ROM v.s. RAM ROM (read only memory) RAM (random access memory)
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ROM v.s. RAM
ROM (read only memory)
ROM contains programs and information essential to operation of the computer.
for permanent data which cannot changed by the user
called as nonvolatile memory
Data does not lost when power off
RAM (random access memory)
for temporary storage of programs that it is running
Data lost when power off
called as volatile memory
ROM: permanent information
tables for character patterns to be displayed on the video monitor,
the programs for testing and finding the total amount of RAM installed on the system
programs to display information on the video monitor.
BIOS
RAM: not permanent, data change with time
various versions of the OS
application packages: office word, tax calculation packages

9. Figure 0-9: Inside the Computer
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Figure 0-9: Inside the Computer
Every computer can be broken down into three parts：
CPU (Central Processing Unit)
Memory：RAM,ROM, etc.
I/O (Input/Output) devices：Peripherals
CPU: execute information stored in memory.
I/O device: provide a means of communicating with the CPU.
Address Bus
Peripherals (monitor, printer, etc.)
CPU
Memory (RAM, ROM, )
Data Bus
Control Bus

10. Bus
CPU is connected to memory and I/O through strips of wire called a bus.
Buses are used to Communicate between the computer components.
Data Bus
Address Bus
Control Bus
Control bus
Address bus
I/O device
CPU
Memory
Data bus

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The Operation of Bus
For a device (memory or I/O) to be recognized by the CPU, it must be assigned an address.
The address of every device must be unique.
The CPU puts the address on the address bus, and the decoding circuitry finds the device.
The CPU uses the data bus either to get data form that device or to send data to it.
The control buses are used to provide read or write signals.
The address bus and data bus determine the capacity of a given CPU.

12. Data Bus The more data buses available, the better the CPU.
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Data Bus
The more data buses available, the better the CPU.
Example：8 bits（slow）, 16 bits, 32 bits, 64 bits（fast）.
An 8-bit data bus can send 1 byte a time.
Data buses are bi-directional.
More data buses mean a more expensive CPU and computer.
The processing power of a computer is related to the size of its buses.
Data bus is like a highway.
More data buses available (increasing the number of lanes 路徑) provide a better pathway between the CPU and its external devices.
8 lines for a 8-bit bus

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Address Bus
The more address buses available, the larger the number of devices that can be addresses.
Example：8 bits（slow）, 16 bits, 32 bits, 64 bits（fast）.
A 16-bit address bus can indicate 216=64K bytes of addressable memory.
Regardless of the size of the data bus.
Address buses are unidirectional.
The number of address lines determines the number of locations with which a CPU can communicate.
All general purpose microprocessor CPUs are what is called byte addressable.
Ask, 8 bit address bus can indicate 28=256 memory cells.
Ask, IBM PC AT uses a CPU with 24 address lines and 16 data lines.
The total accessible memory is 224=16 MB. CPU can access 2 bytes per clock.

14. Central Processing Unit (CPU)
Arithmetic/logic unit (ALU): to perform the arithmetic and logic operation
Control unit: coordinating the machine’s activities
Registers: to store temporary data
Figure 2-1

15. Registers General-purpose registers Special-purpose registers
A,B,R0,R1,R2,...
Register banks: a set of registers (R0..R7)
Special-purpose registers
Program Counter (PC)
Instruction Register (IR)
Program Status Word (PSW)

16. The Registers of Computer
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The Registers of Computer
Workspace R0
General
Registers R1
Instructions R2
... S
Special
Registers IR PC
PSW

17. Machine Clock One bit is send on a wire in a clock period.
Clock is used to synchronize work of the components on the machine.
Clock decides the performance of the computer.
a clock 10
1.4 GHz

18. The Machine Cycle（1/2）
Every instruction in memory is executed by three steps:
Fetch  Decode  Execute
Each instruction has its micro-instruction (or micro-operations).
A micro-operation is an elementary operation that can be performed in parallel during one clock pulse period.
CPU has separate inside units for performing fetch/decode/execution.
The instruction decoder is to interpret the instruction fetched into the CPU.

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The Machine Cycle（2/2）
by instruction decoder
by ALU

20. Internal Organization of Computers Example
8-bit data bus
16-bit address (for a total of 10000H locations)
address 0000-FFFFH
Address Bus
CPU
read /write
RAM
ROM
Printer
Disk
Monitor
Keyboard
Data Bus
Control Bus
Figure 0-10 Internal Organization of Computers

21. Program Example Action Code Data
Move value 21H into register A B0H H
Add value 42H to register A H H
Add value 12H to register A H H

22. Inside Memory 1400 B0 code for moving a value into register A
Memory address
Contents Meaning
B code for moving a value into register A
value to be moved
code for adding a value to register A
value to be added
code for adding a value to register A
value to be added
code for halt

23. Actions Performed by the CPU（1/3）
The PC is set to the value 1400H, indicating the address of the first instruction code to be execution.
The CPU puts 1400H on the address bus and sent it out. The PC is added by 1.
The memory circuitry finds 1400H while the CPU activates the READ signal, indicating to memory that CPU wants the byte at location 1400H.
The content of memory location 1400H, which is B0, to be put on the data bus and brought into the CPU.
The CPU decodes the instruction B0.
PC=1400
PC=1401
PC=1401, IR=B0

24. Actions Performed by the CPU（2/3）
The CPU performs the moving instruction：
The control circuitry ask the content from memory location 1401 (saved in PC).
The PC is added by 1.
Put the value 21H to register A.
After completing one instruction, the PC points to the address of the next instruction to be execute (i.e., 1402H.)
From the memory location 1402H. The CPU fetches code 04H. The PC add 1.
The CPU decoding 04H and ask the parameter in 1803H. The PC add 1.
A = ?, PC=1402, IR=B0
A = 21H, PC=1402, IR=B0
A = 21H, PC=1403, IR=04
A = 21H, PC=1404, IR=04

25. Actions Performed by the CPU（3/3）
The ALU executes the add instruction and sets the value 63H to register A.
From the memory location 1404H, CPU fetches code 04H. The CPU decoding it and ask the parameter. The ALU executes the add instruction and sets the value 74H to register A.
The content of address 1406 are fetched in and executed. This HALT instruction tells the CPU to stop incrementing PC and asking for the next instruction.
A = 63H, PC=1404, IR=04
A = 74H, PC=1406 IR=04
A = 74H, PC=1407, IR=00