Intel 8085

Multiplexing is the process of combining 2 or more signals together into one multi-component signal with all signals being sent to the same receiver or receivers. Demultiplexing is the process of separating the multiplexed signal into its individual component signals. NOTE: The major distinction between multiplexing and multiple access is that in multiple access the signals are coming from many different sources and are going to many different destinations. Multiplexing is used to describe cases in which there is only one source and one destination for the many individual signals.

In an 8086, the address and instruction lines use the same wires, and a pin on the CPU toggles between those two uses. That is one of multiple reasons why the 286 was considerably faster. In addition to a faster clock rate and more dedicated hardware for certain instructions, the 286 had separate address lines and instruction lines. The CPU didn't contain circuitry to switch between the signals and could do addressing and instructions at the same time, and the motherboard was somewhat simpler in that the latches and circuitry to sort the two types of information did not have to be as complex.

Instructions are a given way of following things. They are given in a specific order so the outcome comes out as it was supposed to be in the beginning.

The stack size of Intel's 8085 microprocessor is theoretically 64 kb, but the real limit is a function of memory and program architecture and layout. The stack pointer is 16 bits, but that is not the same as stack size.

List,diagram,paragraph,if-then table

There are eight datalines, D0 through D7, in the 8085 microprocessor. They are shared, or multiplexed with the eight low order address lines, A0 through A7, and are called AD0 through AD7 on the pinout drawing.

The control bus is a unidirectional bus because it can receive the data from any kind of inputs and send back the output. This whole process is done by the data buses.

We have only one flag register of 8 bits.

Bits description is as follows (Assuming D0=LSB & D7=MSB)

D7=Sign Bit.

D6= Zero Flag

D4= Auxiliary Carry Flag

D2 = Parity Flag

D0= Carry Flag.

literal and absolute direct are the registers

An index register has the function of receiving, storing, and outputting instruction-changing codes in a computer. The index register is in a computer's CPU.

Just about any detectable event can be an interrupt for a computer. An event can be something like a keypress on the keyboard, a data stream on a serial input line, when the disk controller detects that the requested data has been read from the disk, when a timer event occurs (some software applications set a timer then "wake up" when the timer expires, that's done with interrupts).

Most hardware is associated with some kind of interrupt vector.

A data bus is bidirectional because the processor needs it to both read and write. Also, in the case of the 4004, the data bus was tri-multiplexed with the 12 bit address bus and the 8 bit opcode bus.

Because that's how Intel designed it.

The 8085 is an 8-bit computer operating on a 16-bit address space.

Data segment

n1 db 20

n2 db 10

sum db ?

Data ends

code segment

assume cs:code,ds:data

start:mov ax,data

mov ds,ax

mov al,n1

mov bl,n2

add al,bl

mov sum,al

mov ah,4ch

int 21h

code ends

end start

The control signals in an 8085 are already generated. They are CLK, S0, S1, ALE, RD-, WR-, IO/M-, INTA-, HLDA, SOD, and RESET OUT. The only control signal that needs to be generated in a medium to large bus organization is DATAENEABLE-. This is optional, if the external logic is compatible but, if not, it needs to be generated from ALE, S1, and CLK, in order to properly drive the data bus buffers without encountering a race condition during WR-. Basically, DATAENABLE- is equal to (RD- when ALE is low) if S1 is high, and it is equal to ALE if S1 is low.

s v i e t k a n u r u .t k

MULTIPLICATION OF TWO 8 -- BIT NUMBERS

AIM:

To perform multiplication of two 8 -- bit numbers using 8051 instruction set.

ALGORITHM:

1.

Get the data in A -- reg.2.

Get the value to be multiplied in B -- reg.3.

Multiply the two data4.

The higher order of the result is in B -- reg.5.

The lower order of the result is in A -- reg.6.

Store the results.

PROGRAM:

ORG 4100CLR CMOV A,#data1MOV B,#data2MUL ABMOV DPTR,#4500MOVX @DPTR,AINC DPTR MOV A,BMOVX @DPTR,AHERE: SJMP HERE

In the 8086/8088 microprocessor, there are eight 8 bit general registers, AH, AL, BH, BL, CH, CL, and DH, DL. They can be used as four 16 bit registers AX, BX, CX, and DX. There are four 16 bit pointer/index registers, SP (stack pointer), BP (base pointer), SI (source index), and DI (destination index). There are four 16 bit segment registers, CS (code segment), DS (data segment), SS (stack segment), and ES (extra segment). There is the 16 bit instruction pointer, IP, and there is a 16 bit flags register.

There is one instruction set in the IA-32. Instruction set is the set of instruction that a processor can execute.

Q.construct a ladder diagram for automatic level control of on roof reservoir for the following two condition.

1)whan water level is below the lower level,switch of the pump should turn on.

11) when water level touches the upper level,the pump should turn off ;it should remain off until the water level reaches below the lower level .

Basically , Demultiplexing is breaking of multiplexed signal .Recall that A/D0 -A/D15 and A16/S3-A19/S6 are the multiplexed signals in 8086.To do so, three demultiplexing latches are used .ALE (Address Enable Latch) is used for strobe Demultiplexing.8086 is 16bit data lines and 20 bit address line microprocessor.BY the Demultiplexing ,we Get A0-A19 separate Address lines and D0-D15 Data lines .

Ajmal Shahbaz

The HOLD pin indicates that an external device wants the 8085 to stop and allow the external device to drive the bus. The acknowledge of control transfer is HLDA, however, it is important to note that HLDA does not mean the current cycle is complete - it means that the current cycle is the last cycle, at which point the 8085 will release the bus. (One half clock cycle later.)

Each instruction of a computer specifies an operation on certain data. The are various ways of specifying address of the data to be operated on. These different ways of specifying data are called the addressing modes. The most common addressing modes are: * Immediate addressing mode * Direct addressing mode * Indirect addressing mode * Register addressing mode * Register indirect addressing mode * Displacement addressing mode * Stack addressing mode To specify the addressing mode of an instruction several methods are used. Most often used are : a) Different operands will use different addressing modes.

b) One or more bits in the instruction format can be used as mode field. The value of the mode field determines which addressing mode is to be used. The effective address will be either main memory address of a register. Immediate Addressing: This is the simplest form of addressing. Here, the operand is given in the instruction itself. This mode is used to define a constant or set initial values of variables. The advantage of this mode is that no memory reference other than instruction fetch is required to obtain operand. The disadvantage is that the size of the number is limited to the size of the address field, which most instruction sets is small compared to word length. INSTRUCTION

OPERAND Direct Addressing: In direct addressing mode, effective address of the operand is given in the address field of the instruction. It requires one memory reference to read the operand from the given location and provides only a limited address space. Length of the address field is usually less than the word length. Ex : Move P, Ro, Add Q, Ro P and Q are the address of operand. Indirect Addressing: Indirect addressing mode, the address field of the instruction refers to the address of a word in memory, which in turn contains the full length address of the operand. The advantage of this mode is that for the word length of N, an address space of 2N can be addressed. He disadvantage is that instruction execution requires two memory reference to fetch the operand Multilevel or cascaded indirect addressing can also be used. Register Addressing: Register addressing mode is similar to direct addressing. The only difference is that the address field of the instruction refers to a register rather than a memory location 3 or 4 bits are used as address field to reference 8 to 16 generate purpose registers. The advantages of register addressing are Small address field is needed in the instruction. Register Indirect Addressing: This mode is similar to indirect addressing. The address field of the instruction refers to a register. The register contains the effective address of the operand. This mode uses one memory reference to obtain the operand. The address space is limited to the width of the registers available to store the effective address. Displacement Addressing: In displacement addressing mode there are 3 types of addressing mode. They are : 1) Relative addressing

2) Base register addressing

3) Indexing addressing. This is a combination of direct addressing and register indirect addressing. The value contained in one address field. A is used directly and the other address refers to a register whose contents are added to A to produce the effective address. Stack Addressing: Stack is a linear array of locations referred to as last-in first out queue. The stack is a reserved block of location, appended or deleted only at the top of the stack. Stack pointer is a register which stores the address of top of stack location. This mode of addressing is also known as implicit addressing.

A register is temporary memory which can store single bit of data....

ISA slots are available in both 8-bit and 16-bit form.