The table below shows part of the code editor reference file used by a theatre to store the initials of lighting operators. Each character has an ASCII dena...
Question 1 Report
The table below shows part of the code editor reference file used by a theatre to store the initials of lighting operators. Each character has an ASCII denary number and an 8-bit binary pattern. The program reads a file containing these codes before it can display an operator's name. The final four bits of each pattern are shown to help staff check that data has not been typed incorrectly.
| Character | ASCII denary number | 8-bit binary pattern |
|---|---|---|
| A | 65 | 01000001 |
| B | 66 | 01000010 |
| D | 68 | 01000100 |
| a | 97 | 01100001 |
A new record contains the binary pattern 01000011. The editor uses standard ASCII code, where the capital letters occur in sequence.
(a) Identify the denary number represented by the binary pattern 1100. [2]
(b) Complete the missing ASCII entry for capital C by writing its denary number and its 8-bit binary pattern. [3]
(c) Give one reason why a computer stores the character C as a binary pattern rather than as the visible character on the display. [2]
(d) Use Table 1 to write the three-character word represented by 01000010 01000001 01000100. [3]
Answer Details
(a) The binary pattern \(1100\) has place values \(8,4,2,1\). Therefore \(8+4=12\), so the denary number is 12. [2]
(b) Capital letters are consecutive in standard ASCII. Since A is 65 and B is 66, capital C is 67. Converting \(67\) to 8 bits gives \(64+2+1\), so its pattern is 01000011. [3]
(c) A computer stores C as binary because its electronic circuits have two reliable states, such as on/off, which can represent 1 and 0. The visible letter is an output shown to a human; internally it is stored as bits. [2]
(d) Decode each 8-bit ASCII pattern using the table: \(01000010\) is B, \(01000001\) is A and \(01000100\) is D. The word is BAD. [3]
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