8251 programmable/communication interface-microprocessor, Assembly Language

8251 Programmable/Communication Interface

As an instance of a serial interface device let us suppose Intel's 8251 A programmable communication interfaces. The 8251A is diagrammed in given figure. It is capable of being programmed for synchronous / asynchronous communication.  The data that is in buffer and data-out buffer registers share the similar port address. For input, the serial bit stream is arriving on the R x D pin is shifted into the receiver shift register and then the data bits are transferred to the data-in buffer register, where they might be input by the CPU. On the other hand on output the data bits put in the data-out buffer register by the CPU are transferred to the transmitter shift register and, along with the essential synchronization bits, are shifted out through the T x D pin. Among other things the contents of the mode register, which are begin by the executing program, determine whether the 8251A is in synchronous mode or asynchronous mode and the format of the characters being received and transmitted. The control register, which is set by the program, controls the operation of the interface, and the status register makes sure information available to the executing program. Obviously, the sync character registers are for storing the sync characters required for synchronous communication.

1142_8251.jpg

Even though all 7 of the registers on the left side of Figure 4.7 may be accessed by the processor, the 8251A is associated with only 2 port addresses. The C/D pin is linked to the address line AO and AO differentiates the 2 port addresses. The 8251A internally interprets the C/D, RD, and WR signals as follows:

1611_8251 signals.jpg

Posted Date: 10/10/2012 7:45:42 AM | Location : United States







Related Discussions:- 8251 programmable/communication interface-microprocessor, Assignment Help, Ask Question on 8251 programmable/communication interface-microprocessor, Get Answer, Expert's Help, 8251 programmable/communication interface-microprocessor Discussions

Write discussion on 8251 programmable/communication interface-microprocessor
Your posts are moderated
Related Questions
SBB: Subtract  with Borrow  :- The subtract with borrow instruction subtracts the source operand and the borrow flag (CF) which might reflect the result of the past calculations,

2. Write a program to separate out positive and negative numbers from a given series of 16-bit hexadecimal numbers.

to find the matrix addition

INC: Increment : - This instruction increments the contents of the particular memory or register location by the value 1. All the condition code flags are affected except the carry

III rd Generation Microprocessor: The single 3rd generation microprocessor chip having 64-pins began with the introduction of 16-bit Intel 8086 in 1978. The other essential

Tabular comparison for µ PS' Parameters Tables (a) and (b) list the characteristic of Intel microprocessor. Table(a):   Table(b): It has a 64 bit da

Logical Instruction : This type of instructions is utilized for carrying out the bit by bit shift, basic logical operations or rotate. All of the condition code flags are affe

Read Architecture: Look Through Main memory that located is conflicting the system interface. The least concerning feature of this cache unit is that it remain between the proc

ASSUME: Assume Logical Segment Name:- The ASSUME directive which is used to inform the assembler, the specified names of the logical segments to be consider for different segme

implement the following c++ code in assembly language using the block-structured .IF and .while directives