This document describes the internal organization and logic circuits of a computer system using a register transfer language. It includes: 1) A table summarizing the control functions and micro-operations for the entire computer. This describes the internal organization and allows designing the computer's logic circuits. 2) Examples of register transfer statements and control functions/conditional statements that formulate the control unit's Boolean functions. 3) A list of micro-operations specifying the types of control inputs needed for registers and memory. 4) Diagrams showing the control logic for flip-flops and buses, the accumulator logic, and an adder/logic circuit stage. 5) Examples of exercises analyzing register transfers and microoperations in the system

1. Computer Organization
Instructors :
Dr. Abdul Raouf Khan
Mr.Marwan El-Haj

2. Computer Organization
Lec.11:Complete Computer Description

3. Last Lecture

4. Basic Computer Consists of:

5. Complete Computer Description
A Register Transfer Language useful for describing
internal organization of a digital system, and logic
circuits needed for its design
– Table 5-6 Summarizes:
 Control Functions for Entire Computer
 Micro-operations for Entire Computer
– Register Transfer Statements
 Describes Internal organization.
 Information to design logic circuits of computer.
– Control Functions and conditional control statements
 Formulates Boolean functions for control units gates
– List of micro-operations
 Specifies types of control inputs needed for registers and memory

10. Control Gates Associated with AR

11. Control of Single FLIP FLOP
 The control gates for the seven flip flops can
be determined in a similar way. For example
 IEN may change as result of two instructions
ION & IOF
pB7: IEN1
pB6: IEN0 where p=D7IT3 also
RT2: IEN0 at the end of Interrupt cycle
Figure below shows the control logic

12. Control of Single FLIP FLOP

13. Control of Common BUS

14. Control of Common BUS

15. Design of Accumulator Logic

16. Control of AC register

18. Adder & Logic Circuit
 The adder and logic circuit can be divided into
16 stages, with each stage corresponding to
one bit of AC.
 The one stage of adder and logic circuit is
shown as below.

20. Assignments
1. A computer uses a memory unit with 256K words of 32
bit each. A binary instruction code is stored in one word
of memory. The instruction has four parts: an indirect
bit, an operation code, a register code part and the
address part. The system has 32 registers.
a. How many bits are there in the operation code, the
register code part and the address code part?
b. Draw the instruction word format
c. How many bits are there in the data & address inputs of
the memory?
d. What is the maximum number of instructions we can
have in this computer?

21. Exercise 1
 The following control inputs are active in our
BUS system. For each case specify the
register transfer that will be executed during
next clock
 S2 S1 S0 LD of register Memory Adder
A 1 1 1 IR Read --
B 1 1 0 PC --- --
C 1 0 0 DR Write --
D 0 0 0 AC -- Add

22. Exercise 2
 The following register transfers are to be executed in our System.
For each transfer, specify (1). the binary value to be applied to bus
select inputs S0,S1, S2. (2) the register whose LD control must be
active (3) a memory READ or Write (if needed) (4) the operation in
the adder & logic circuit.
 a. AR PC
 b. IR M[AR]
 c. M[AR]TR
 d. ACDR, DRAC (done simultaneously)

23. Exercise 3
 Explain why each of the following
microoperations cannot be executed during a
single clock in the system.
 a. IRM[PC]
 b. AC AC+TR
 c. DR DR + AC (AC does not change)