Reading and writing data
When Quantum reads a column of data, it does one of three things:
▪If the data is a standard ASCII character, Quantum finds its position in the ASCII character set and then looks up the octal code in the corresponding cell of the punch array. For example, if the column contains the letter A, which is in position 101, Quantum will look in cell 101 of the punch array and will find code 4400 (the same as 100100000000 or ‘&1’). It stores this code as the data for that column.
▪If the data is a character in the extended character set, the position for that character will be set to zero. Quantum therefore stores a blank as the data for this column.
▪If the data is a miscellaneous multicode which does not correspond to a character, Quantum puts an asterisk in the column and stores the codes it has read at the end of the card.
The same actions are taken, but in reverse, when you write your Quantum data out to a file. Quantum reads the octal punch code for the current column and finds its cell number in the punch array. It then writes out the character in the corresponding cell of the ASCII character set. For example, if the punch code is 4400 which is in cell 101 of the punch array, Quantum will output the character in cell 101 of the ASCII array; namely, the letter A.
If the column is stored as blank, an empty column will appear in your data. If the column is stored as a miscellaneous multicode, Quantum will write out that multicode.
If Quantum makes the wrong association between the ASCII character set and the punch array, your data will not be the same when you write it out as when you read it in.
See also