Thumbnail
Access Restriction
Subscribed

Author Baker, James J.
Source ACM Digital Library
Content type Text
Publisher Association for Computing Machinery (ACM)
File Format PDF
Language English
Abstract Scanning text on a computer, as in forming word lists or editing, usually involves isolating and identifying certain characters or classes of characters. For example, if we scan text to form a list of words, the definition of “word” might be “everything between two blanks that isn't punctuation.” To program this, we must be able to identify a single character (blank) and a class of characters (punctuation). In a computer such as the 7090, where characters are numbers, we can put a character into an index register and index a table of transfers (one table-entry per character), thus getting to a section of code appropriate for handling that particular character. This is not natural for the 1401 because characters are not numbers and turning them into numbers is a bit clumsy. However, 1401 addresses are a combination of numbers and other characters, and we can use characters directly to reference certain addresses provided we can turn all characters (there are 64) into the 40 that are allowable in specifying an address.
Description Affiliation: Cambridge, MA (Baker, James J.)
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 2005-08-01
Publisher Place New York
Journal Communications of the ACM (CACM)
Volume Number 7
Issue Number 12


Open content in new tab

   Open content in new tab
Source: ACM Digital Library