Computer Fundamental arithmetic logic unit Memory segment

Computer Fundamental arithmetic logic unit Memory segment 

shortcomings of ENIAC. It presented an impressive feat electronic engineering  and used for many year to solve ballistic problems.

1.    Describe about output unit and ARITHMETIC LOGIC UNIT

 

Answer: The job of an output unit is just the reverse of that of an input unit. It supplies information and results of computation to the outside world. Thus it links the computer with the external environment As computers work with binary code, the results produced are also in the binary form. Hence, before supplying the results to the outside world, it must be converted to human acceptable (readable) form. This task is accomplished by units called output interfaces. Output interfaces arc designed to match the unique physical or electrical characteristics of output devices (terminals, printers, etc.) to the requirements of the external environment.

In short, the following functions are performed by an output unit:

1.   h accepts the result produced by the computer which are in coded rum and hence cannot be  easily understood by u

2.   It  converts these  coded  results   to  human acceptable (readable)              from

3.   II supplies the convict cod insults lo the outside work

             ARITHMETIC LOGIC UNIT

The arithmetic logic unit (ALU) of a computer system is the place where the actual execution of the instructions takes place during the processing operation. To the more precise. Ill calculations. re performed and all comparisons (decisions) are made in the ALU. The data and instructions, stored in the primary storage prior to processing, are transferred as and when needed to the ALU where processing takes place. No processing is done in the primary storage unit Intermediate faults generated in the -ALU arc temporarily transferred badly. to the primary storage until needed at a later time. Data may thus move from primary storage to ALU and back again lo storage many times before the processing is over.  After the completion of processing, the final re suit, which are stored in the storage unit arc released to an output device.

The and number of arithmetic and loge operations (hat a computer can perform is determined by the engineering design of the ALU.  However almost all

Memory Segment

Memory Segment : A memory segment is a block of 2¹⁶ consecutive memory location /bytes, starting with 0. A segment number is 16 bits, so the highest segment number is FFFFh.

   Within a segment, a memory location is specified by giving an offset. This is the number of bytes from the beginning  of the segment offset can be given as a 16 bit number.

The first byte in a segment has offset 0 and the last offset in a segment is FFFFh.

Thus a memory location can be specified by providing a segment number and an offset. For example A4FB : 4872h . Means 4872h offset within the segment A4FBh.

Thus from of addressing is know as logical address.

Physical address :

Segment 0 starts with offset 0. so the physical address of segment 0’s starting.

Segment 0 onto with offset FFFFh so the physical address of segment 0’s ending is.

              Segment               Offset

               0000h                  0000h

         0000 X 10h + 0000h = 00000 + 0000 = 00000h

From the calculation, we have seen that every segment starts after 10h = 16 bytes. And one segment overlaps with another. For this reason we call every 10h a paragraph and we call an address that is divisible by 16 a paragraph boundary.

* Logical address = Segment : Offset

* Physical address = Segment X 10h + Offset