This document discusses symbolic and binary microprograms. A symbolic microprogram uses symbols in microinstructions like an assembly language, while a binary microprogram represents a symbolic microprogram in binary using a microprogram assembler. It provides examples of fields in microinstructions and their symbolic and binary codes to define the functions of a microprocessor at a low level.

1. Microprocessor and Computer
Architecture
Topic: (Symbolic and binary Microprogram)
Presented by : Gitima Basnet
Roll No: 15

2. Micro Program
• Microprogramming is the process of writing
microcode for a microprocessor. Microcode is
a low-level code that defines how a
microprocessor should function when
execute that typically consists of machine
language instructions which are stored in
ROM and in some cases it is stored in EPROM.

3. Micro program
Symbolic Micro program Binary Micro program

4. Symbolic Micro Program
The microprogram in which symbols are used in
microinstructions as in assembly language is called
symbolic microprogram.
3 3 3 2 2 7
Binary micro program
When the symbolic microprogram is represented in
binary form i.e. control words using microprogram
assembler is called binary microprogram.
F1 F2 F3 CD BR AD

5. Symbols and Binary codes for Microinstructions Fields
F1 Micro operation Symbol
000 None NOP
001 AC AC + DR ADD
010 AC 0 CLRAC
011 AC AC + 1 INCAC
100 AC DR DRTAC
101 AR DR (0 - 10) DRTAR
110 AR PC PCTAR
111 M[AR] B DR WRITE

6. F2 Micro operation Symbol
000 None NOP
001 AC AC – DR SUB
010 AC AC v DR OR
011 AC AC ^ DR AND
100 DR M[AR] READ
101 DR AC ACTDR
110 DR DR + 1 INCDR
111 DR (0 – 10 ) PC PCTDR
F3 Micro operation Symbol
000 None NOP
001 AC AC – DR XOR
010 AC AC’ COM
011 AC shl AC SHL
100 AC shr AC SHR
101 PC PC + 1 INCPC
110 PC AR ARTPC
111 RESERVED

7. CD Symbol Comments
00 U – 1 Unconditional Branch
01 I – DR (15) Indirect Address Bit
10 S – AC(15) Sign bit of AC
11 Z – AC = 0 Zero value in AC
BR Symbol Function
00 JMP CAR AD if (condition = 1), CAR AR + 1 if condition = 0
01 CALL CAR AR , SBR AR + 1 if condition= 1, CAR CAR + 1 if
condition = 0
10 RET CAR SBR (Return from subroutine)
11 MAP Car (2 -5) DR(11-13), CAR(0,1,6) 0

8. Microprogram to binary program
ORG 64
FETCH: PCTAR U JMP NEXT
READ, INCPC U JMP NEXT
DRTAR U MAP
ADDRESS F1 F2 F3 CD BR AD
1000000 110 000 000 00 00 1000001
1000001 000 100 101 00 00 1000010
1000010 101 000 000 00 11 0000000