In what way and differs and features. It can be easily interfaced with microprocessor. PIN Diagram 1. AD0-AD. HOLD: It indicates that another device is requesting the use of the address and data bus. Having received HOLD request the microprocessor relinquishes the. 2. Case study: Interfacing the The is a special chip designed by Intel to work with the to demonstrate the interfacing of the MPU. The

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This page was last edited on 16 Novemberat Discontinued BCD oriented 4-bit The CPU is one part of a family of chips developed by Intel, for building a complete system.

The parity flag is set according to the parity odd or even of the accumulator. An improvement over the is that the can itself drive a piezoelectric crystal directly connected to it, and a built-in intetfacing generator generates the internal high amplitude two-phase clock signals at half the crystal frequency a 6. The incorporates the functions of the clock withh and the system controller on chip, increasing the level of integration. In many engineering schools [7] [8] the processor is iterfacing in introductory microprocessor courses.

A downside compared to similar contemporary designs such as the Z80 is the wiith that the buses require demultiplexing; however, address latches in the Intel, and memory chips allow a direct interface, so an along with these chips is almost a complete system. The screen and keyboard can be switched between them, allowing programs to be assembled on one processor large programs took awhile while files are edited in the other.

Later an external box was made available with two more floppy drives. For example, multiplication is implemented using a multiplication algorithm.

More complex operations and other arithmetic operations must be implemented in software. All 2-operand 8-bit arithmetic and logical ALU operations work on the 8-bit accumulator the A register.

All interrupts are enabled by the EI instruction and intrfacing by the DI instruction. This capability matched that of the competing Z80a popular derived CPU introduced the year before.


As in many other 8-bit processors, all instructions are encoded in a single byte including register-numbers, but excluding eith datafor simplicity. Operations that have to be implemented by program code subroutine libraries include comparisons of signed integers as well as multiplication and division.

interfacing – Microprocessor Course

Direct copying is supported between any two 8-bit registers and between any 8-bit register and a HL-addressed memory cell, using the MOV instruction. There are also eight one-byte call instructions RST for subroutines located at the fixed addresses 00h, 08h, 10h, Adding HL to itself performs a bit arithmetical left shift with one instruction. SIM and RIM also allow the global interrupt mask state and the three independent RST interrupt mask states to be read, the pending-interrupt states of those same three interrupts to be read, the RST 7.

The uses approximately 6, transistors. Also, the architecture and instruction set of the are easy for a student to understand.

Intel – Wikipedia

Although the is an 8-bit processor, it has some bit operations. Unlike the it does not multiplex state signals onto the data bus, but the 8-bit data bus is instead multiplexed with the lower 8-bits of the bit address bus to limit the number of pins to The can also be clocked by an external oscillator making it feasible to use the in synchronous multi-processor systems using a system-wide common clock for all CPUs, or to synchronize the CPU to an external time reference such as that from a video source or a high-precision time intdrfacing.

One sophisticated instruction is XTHL, which is used for exchanging the register pair HL woth the value stored at the address indicated by the stack pointer. In other projects Wikimedia Commons. An immediate value can also be moved into any of the foregoing destinations, using the MVI instruction.

The is a binary compatible follow up on the Lastly, the carry flag is set if a carry-over from bit 7 of the accumulator the MSB occurred. The only 8-bit ALU operations that can have a destination other than the accumulator are the unary incrementation or decrementation instructions, which can operate on any 8-bit register or on memory addressed by HL, as for two-operand 8-bit operations.


Later and support was added including ICE in-circuit emulators. Sorensen in the process dith developing an assembler. A Iwth “no operation” instruction exists, but does not modify any of the registers or flags.

Intel 8085

These are intended to be supplied by external hardware in order to invoke a corresponding interrupt-service routine, but are also often employed as fast system calls. However, it requires less support circuitry, allowing simpler and less expensive microcomputer systems to be built. For two-operand 8-bit operations, the other operand can be either an immediate value, another 8-bit register, or a memory cell addressed by the bit register pair HL.

Due to the regular encoding of the MOV instruction using nearly a quarter of the entire opcode space there are redundant codes to copy a register into itself MOV B,Bfor instancewhich are of little use, except for delays.

The original development system had an processor.

Pin 39 is used as the Hold pin. The is supplied in a pin DIP package. These instructions are 1855 in the form of a program which is used to perform various operations such as branching, addition, subtraction, bitwise logicaland bit shift operations. Many of these support chips were also used with other processors. Retrieved 31 May This was typically longer than the product life of desktop computers.

Software simulators are available for the microprocessor, which allow simulated execution of opcodes in a graphical environment. Subtraction and bitwise logical operations on 16 bits is done in 8-bit steps. It also has a bit program counter and a bit stack pointer to memory replacing the ‘s internal stack.