F453 Explain Flashcards

Question

Explain the term register

Answer 1

 a location in the processor  used for a particular purpose  (temporarily) stores data/or control information  explained example of contents held by named register

Answer 2

advantages:  allows faster processing  more than one instruction (of a program) is processed at the same time  different processors can handle different tasks/parts of same job disadvantages:  operating system is more complex...  …to ensure synchronisation  program has to be written in a suitable format  Program is more difficult to test/write/debug

Answer 3

 maximum (positive) number in this format |  as mantissa & exponent each have their largest values

Answer 4

 (information about) an item of data…  …supplied to a procedure or function  may be passed by reference or by value  used as a local variable

Answer 5

 used in indexed addressing  stores a number used to modify an address…  … which is given in an instruction  allows efficient access to a range of memory locations/by incrementing the value in the IR  eg used to access an array

Answer 6

 foreign key links tables (to represent many to one relationship)…  …so that only one record is accessed/to avoid duplicate data  eg primary key from B used as foreign key in C from (a)  primary key is in a table that may contain data not required in another table  eg primary key from C is not used in B and hence cannot be a foreign key

Answer 7

 CHAR is fixed length |  VARCHAR is variable length

Answer 8

 use of backing store…  …as additional memory  uses paging / swapping pages (between memory & backing store)  holds part of the program not currently in use  allows large programs to run (when memory size is insufficient)

Answer 9

 a map of where files are stored…  …in backing store/hard disk  provides addresses/pointers to (start of) files  stores file names  stores file sizes  stores access rights  identifies free space  is updated by the operating system when files are saved/deleted  Is used by the operating system when files are accessed

Answer 10

 the original code/code written by the programmer…  …often in a high level language  may be in assembly language  source code can be understood by people…  …but cannot be executed (until translated)

Answer 11

``` Library routines:  routines are pieces of software…  …which perform common tasks…  …such as sorting/searching  routines are compiled Why library routines help programmers:  routines are error-free/have already been tested  already available/ready to use/saves work/saves time  routines may be used multiple times  routines may have been written in a different source language  allows programmer to use others’ expertise How routines are used:  linker is used…  …to link routine with program  loader handles addresses…  …when program is to be run ```

Answer 12

```  uses (complex) instructions each of which may take multiple cycles  single register set  instructions have variable format  many instructions are available  many addressing modes are available ```

Answer 13

 +5¼ = 101.01 in pure binary  mantissa is 010101, but only 4 bits allowed…  …so mantissa would be 0101 (5 stored, not 5¼)  value stored is inaccurate/precision lost  exponent is 0011 (3)  number would be stored as 01010011

Answer 14

 address field (in an instruction)  it holds data…  to be used by the operation given in the opcode  eg in ADD 12, “12” is the operand

Answer 15

 presentation of selected data…  …usually in the form of a table/specific layout  may be defined in advance…  …so the user does not need to set it up Features of report definition  a query  a display order

Answer 16

 Interrupt register is checked…  when each cycle completed  by comparing priority of the current task with interrupt register

Answer 17

```  holds data being processed  temporary storage of intermediate results (in the ALU)  is where calculations are performed  input & output data passes through ```

Answer 18

advantage:  (usually) faster because…  …fewer items are checked/more efficient for large files disadvantage:  items must be in an order…  …to allow appropriate items to be discarded

Answer 19

 give information about instances of a class… |  …& how they link (at specific times)

Answer 20

```  message/interaction…  …from one object to another on diagram  arrow…  with appropriate label ```

Answer 21

 a variable defined at the start of a program  exists throughout program…  including functions & procedures  allows data to be shared by modules  overridden by local variables with same name  eg VAT rate

Answer 22

```  a variable defined within one module…  & only accessible in that module  data is lost when module is completed  same variable name may be used in different modules  eg loop counter ```

Answer 23

 faster to access than Random Access Memory  used for specific purposes…  …which involve frequent access

Answer 24

 ensure all jobs are processed/changing priorities where necessary  process as many jobs as possible (in the least possible time)  maximise number of interactive users…  …receiving fast response times  utilise resources/processor time efficiently

Answer 25

 an “order of importance”… |  as some jobs are needed more urgently than others

Answer 26

 to allow it to be processed  otherwise if higher priority jobs keep occurring /it would have to wait indefinitely

Answer 27

 value is too large/out of range/exponent is too small  maximum value stored is 0111 0111  …which is 1110000. = 112  value is 1.0001  mantissa needed is 010001…  which has 6 bits but only 4 are available…  so exact value cannot be stored

Answer 28

```  a class that has all the attributes & operations of its superclass…  …& may have attributes & operations of its own ```

Answer 29

```  block of code/set of instructions/subroutine/subprogram/module…  which performs a task  receives parameter values  uses local variables  may return value(s) ```

Answer 30

```  supplied to a procedure (or function)  pass values between functions/procedures  passed by reference…  …or by value  used as a local variable ```

Answer 31

```  machine-oriented language  related to design of computer  includes assembly language/machine code  may use mnemonics (for operations)  may use labels (for addresses) ```

Answer 32

opcode is the instruction to be executed, in this case ADD | operand is the value/address of the data, in this case 45

Answer 33

A secondary key is made on a field that you would like to be indexed for faster searches. A table can have more than one secondary key.

Answer 34

-Location in the processor -Used for a particular purpose -Temporarily stores data/control information Allows very high speed access. -

Answer 35

. Maximum value is 011011  Exponent is 3,  Mantissa 0.11, move point 3 places right becomes 0110 = +6  Maximum value is +6 so +16 can’t be represented. Or  +16 pure binary is 010000  Mantissa is 0.10  Point moves 5 places so exponent is +5 or 0101 …  …which cannot be written in 3 bit twos complement.

Answer 36

 Close to design of processor  Can access memory locations directly  The processor in the washing machine has a limited memory.

Answer 37

``` . Reflects type of problem/problem-oriented  Allows use of mathematical functions  Portability  Uses library routines  Complexity of problem  Easy to maintain ```

Answer 38

 Uses address field as a pointer…  …to address to be used  Increases the size of the address that can be used…  ….allowing a wider range of memory locations to be accessed

Answer 39

.Insertion sort:  Insert one number at a time into correct position…  …so list of sorted numbers is built up Insertion sort on set of numbers given:  Insert 25 into new file: 25, 7, 48, 19, 32, 21  Insert 7: 7, 25, 48, 19, 32, 21  Insert 19: 7, 19, 25, 48, 32, 21  Insert 48: 7, 19, 25, 48, 32, 21  Insert 32: 7, 19, 25, 32, 48, 21  Insert 21: 7, 19, 21, 25, 32, 48 – sort complete.