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1. Convert the decimal number 321.145 to octal andhexadecimal.
Ans.125 / 8^2 =1125 ((8^2)*1) = 6161 / 8^1 =7
61 ((8^1)*7) =5Therefore, 12510= 1758.321.145 = 321/8^
2. Write an assembly language program to find the smallestamong
twonumbers.Ans.
ProgramMVI B, 30HMVI C, 40HMOV A, BCMP CJZ EQUJC SMLOUT
PORT1HLTEQU: MVI A, 01HOUT PORT1HLT
SML: MOV A, COUT PORT1
HLT
OR
.model small
.stack 64
.data
n1 db 08h,02h
res db ?
.code
mov ax,@data.
mov ds,ax
mov cx,02
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Data BusData Bus: carries data, in binary form, between
microprocessor andotherexternal units, suchas memory. Typical size
is 8 or 16 bits. TheData Bus typically consists of 8 wires.
Therefore, 28combinations ofbinary digits. Data bus used to
transmit data, ie information, resultsofarithmetic, etc, between
memory and the microprocessor. Bus is bi-directional. Size of
thedata bus determines what arithmetic can bedone. If only 8 bits
wide then largest number is
11111111 (255 indecimal). Therefore, larger number have to be
broken down intochunks of255. This slows microprocessor. Data Bus
also carriesinstructions from memory to themicroprocessor. Size of
the bustherefore limits the number of possible instructions to
256,eachspecified by a separate number.
Control BusControl Bus are various lines which have specific
functions forcoordinating and controllingmicroprocessor operations.
Eg:Read/NotWrite line, single binary digit. controls whether
memoryisbeing written to (data stored in mem) or read from (data
taken outof mem) 1 = Read, 0 =Write. May also include clock line(s)
fortiming/synchronising, interrupts, reset etc.
Typicallymicroprocessorhas 10 control lines. Cannot function
correctly without these vitalcontrol signals.
CPU ArchitectureControl UnitGenerates signals within
microprocessor to carry out the instruction,which has been decoded.
Inreality causes certain connectionsbetween blocks of the
microprocessor to be opened or closed,so thatdata goes where it is
required, and so that ALU operations occur.
Arithmetic Logic UnitThe ALU performs the actual numerical and
logic operation such asadd, subtract, AND,OR, etc. Uses data from
memory and fromAccumulator to perform arithmetic. Always
storesresult of operation inAccumulator.
RegistersThe 8085/8080A-programming model includes six
registers, oneaccumulator, and one flagregister, as shown in Fig.
2.1 In addition, ithas two 16-bit registers: the stack pointer and
theprogram counter. They are described briefly as follows. The
8085/8080A has six general-purpose registers to store 8-bit
data;these are identified as B,C,D,E,H and L as shown in
thefigure.
