Types of microprocessor

Depending on register

1. Accumulator based

2. Register based

Based on aplication

1. Bit Slice Processors

2. General purpose CPUs

3. Dedicated/Embedded controllers

Accumulator based microprocessors

• Examples are -Intel’s 8085, Motorola’s 6809• also called a 1-operand machine• Here, one of the operands is assumed to be held a special register

called“accumulator”.• although it may have several registers, all arithmetic and logic

operations are performed using this register as one of the data source and result is stored back in the accumulator.

• All the Data transfer are performed through accumulator.• For instance, a CPU might have an instruction like: ADD

memaddress that adds the value read from the memory location at memaddress to the value from the accumulator, placing the result in the accumulator. The accumulator is not identified in the instruction by a register number; it is implicit in the instruction and no other register can be specified in the instruction.

Block diagram of Accumulator based microprocessors

The general-purpose register based microprocessors

• Examples are -Intel’s 8086/386, Motorola’s 68000/020

• Also called 2-operand or 3-operand machines.• These processors have a set of general purpose registers which can be used

to hold data, memory addresses or the results of an arithmetic or logic operations for indefinite amount of time and are capable of manipulating data by shift or rotate operations.

• The number and size of these registers vary from processor to processor

• Some registers are general purpose while others are earmarked with some functions.

• Typical dedicated registers include,– a. Program Counter (PC)

– b. Instruction Register (IR)

– c. Status Register or Flag Register

– d. Stack Pointer (SP)

Block diagram of Register based microprocessors

Difference between Accumulator

and register based MP

Accumulator based MP

1.All operands are held in

accumulator.

2.Result after arithmetic and

logic operation stored in the

accumulator.

3.One address instructions are

very predominate in this

organization.

4.8-bit mp is usually accumulator

based.

5.Lower speed.

Register based MP

1.Register is used to hold

memory and data.

2.Stored in the register.

3.The number size types of

register vary from one mp to

another.

4.16-bit and 32-bit usually

register based.

5.Higher speed.

Difference between Accumulator

and register based MP

Accumulator based MP Register based MP

6.Data transfer are performed

via accumulator.

6.Via register.

7. Are made by NMOS

technique.

8.Example-intel 8085

Motorola-6800

7. Are Made by HMOS

technique

8.Example intel-8086 80386

Motorola-68020,68030

Bit slicing concept

Bit slicing is a technique for constructing a

processor from modules of smaller bit width.

Each of these components processes one bit field or

"slice" of an operand.

The grouped processing components would then

have the capability to process the chosen full word-

length of a particular software design.

Bit slice processor

In a bit-sliced processor, each module contains an ALU

(arithmetic-logic unit) usually capable of handling a 4-bit field.

By combining two or more identical modules, it is possible to

build a processor that can handle any multiple of this value,

such as 8 bits, 12 bits, 16 bits, 20 bits, and so on.

Examples of bit-slice microprocessor modules can be seen in

the Intel 3000 family, the AMD Am2900 family, the National

Semiconductor IMP-16 and IMP-8 family, and the 74181.

CMOS VLSI DesignCMOS VLSI Design

Block diagram of bit

slice microprocessors

Case Study: Intel Processors Slide 10

CMOS VLSI DesignCMOS VLSI Design

Dedicated/Embedded Controllers

Embedded systems are systems that are dedicated

to perform specific functions.

They differ from conventional computer systems in

that they are not required to be general purpose.

Microcontrollers are embedded controllers.

Case Study: Intel Processors Slide 11

MICROCONTROLLER

• Microcontroller (MCU)– Integrated electronic computing device that includes three major components on a single

integrated circuit chip• Microprocessor (MPU)• Memory(RAM and ROM)• I/O (Input/Output) ports

• Support Devices– Timers– A/D converter– Serial I/O

• Common communication lines– System Bus

Having the complete controller on a single chip allows the hardware design to be simple.

Microcontrollers are used increasingly in products as varied as industrial applications, home appliances, and toys.

BLOCK DIAGRAM OF MICROCONTROLLER

Microcontroller vs. Microprocessors

1. A smaller computer

2. On-chip RAM, ROM, I/O ports...

3. Example：Motorola’s 6811,

Intel’s 8051, Zilog’s Z8 and PIC

1. CPU for Computers

2. No RAM, ROM, I/O on CPU chip itself

3. Example：Intel’s x86, Motorola’s 680x0

Microcontroller vs. Microprocessors

Microprocessor

1. CPU is stand-alone, RAM,

ROM, I/O, timer are separate

2. designer can decide on the

amount of ROM, RAM and

I/O ports.

3. general-purpose

Microcontroller

1. CPU, RAM, ROM, I/O and

timer are all on a single chip

2. fix amount of on-chip ROM,

RAM, I/O ports

3. single-purpose