The Automatic Proofreader is a series of

checksum A checksum is a small-sized block of data derived from another block of digital data for the purpose of detecting errors that may have been introduced during its transmission or storage. By themselves, checksums are often used to verify dat ...

utilities published by COMPUTE! Publications for its ''

COMPUTE! ''Compute!'' (), often stylized as ''COMPUTE!'', was an American home computer magazine that was published from 1979 to 1994. Its origins can be traced to 1978 in Len Lindsay's ''PET Gazette'', one of the first magazines for the Commodore PET c ...

'' and ''

COMPUTE!'s Gazette ''Compute!'s Gazette'' (), stylized as ''COMPUTE!'s Gazette'', was a computer magazine of the 1980s, directed at users of Commodore's 8-bit home computers. Announced as ''The Commodore Gazette'', it was a Commodore-only daughter magazine of t ...

'' magazines, and various books. These programs are designed to allow home computer users to easily detect errors on

BASIC BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...

type-in program A type-in program or type-in listing was computer source code printed in a home computer magazine or book. It was meant to be entered via the Keyboard (computing), keyboard by the reader and then saved to Compact Cassette (data), cassette tape or ...

s, and work by displaying a

hash value A hash function is any function that can be used to map data of arbitrary size to fixed-size values. The values returned by a hash function are called ''hash values'', ''hash codes'', ''digests'', or simply ''hashes''. The values are usually ...

for each line entered that can be compared against the reference value printed in the magazine. Initially published for use with the Commodore 64 and

VIC-20 The VIC-20 (known as the VC-20 in Germany and the VIC-1001 in Japan) is an 8-bit home computer that was sold by Commodore Business Machines. The VIC-20 was announced in 1980, roughly three years after Commodore's first personal computer, the ...

in 1983, the Proofreader was later made available for the

Atari 8-bit family The Atari 8-bit family is a series of 8-bit home computers introduced by Atari, Inc. in 1979 as the Atari 400 and Atari 800. The series was successively upgraded to Atari 1200XL , Atari 600XL, Atari 800XL, Atari 65XE, Atari 130XE, Atari 800XE ...

Apple II family The Apple II series (trademarked with square brackets as "Apple ] ''" and rendered on later models as "Apple //") is a family of home computers, one of the first highly successful mass-produced microcomputer products, designed primaril ...

, and

IBM PC The IBM Personal Computer (model 5150, commonly known as the IBM PC) is the first microcomputer released in the IBM PC model line and the basis for the IBM PC compatible de facto standard. Released on August 12, 1981, it was created by a tea ...

PCjr The IBM PCjr (pronounced "PC junior") was a home computer produced and marketed by IBM from March 1984 to May 1985, intended as a lower-cost variant of the IBM PC with hardware capabilities better suited for video games, in order to compete mor ...

as well. The line-by-line "real-time" feedback feature was something of a novelty at the time and represented a significant improvement over earlier checksum utilities, which were typically run only after a user program had been entered and, due to quite simplistic checksum algorithms, had trouble catching errors like transposed characters.

Commodore versions

The Automatic Proofreader was first introduced in October 1983 for the Commodore 64 and VIC-20. This first version had separate versions for the VIC and 64; the following month, they were combined into a single listing designed to work on both systems. This version of the Proofreader would display a

byte The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit ...

-sized numeric value at the top left corner of the screen whenever a program line was entered. The initial version of the Proofreader, however, had several drawbacks. It was loaded into the cassette buffer (memory area), which was overwritten whenever a program was loaded or saved using the

Datassette The third, most common version of the 1530 C2N Datassette The Commodore 1530 (C2N) Datasette, later also Datassette (a portmanteau of ''data'' and ''cassette''), is Commodore's dedicated magnetic tape data storage device. Using compact cassette ...

. This caused difficulties if a cassette user had to resume work on a partially completed listing. A complicated method had to be used to get both the Proofreader and the program listing in memory at the same time. Also, the checksum method used was relatively rudimentary, and did not catch transposition errors, nor did it take

whitespace White space or whitespace may refer to: Technology * Whitespace characters, characters in computing that represent horizontal or vertical space * White spaces (radio), allocated but locally unused radio frequencies * TV White Space Database, a mec ...

into account. Because of this, the New Automatic Proofreader was introduced in February 1986. This version used a more sophisticated checksum algorithm that could catch transposition errors. It also took spaces into account if they were within quotes (where they were generally significant to the program's operation), while ignoring them outside of quotes (where they were not relevant). Also, the decimal display of the checksum was replaced by two letters. The New Automatic Proofreader was designed to run on any Commodore

8-bit In computer architecture, 8-bit integers or other data units are those that are 8 bits wide (1 octet). Also, 8-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers or data buses of ...

home computer (including the C16/ Plus/4 and C128), automatically relocating itself to the bottom of BASIC

RAM Ram, ram, or RAM may refer to: Animals * A male sheep * Ram cichlid, a freshwater tropical fish People * Ram (given name) * Ram (surname) * Ram (director) (Ramsubramaniam), an Indian Tamil film director * RAM (musician) (born 1974), Dutch ...

and moving pointers to hide its presence. It was continuously published until ''COMPUTE!'s Gazette'' switched over to a disk-only format after the December 1993 issue.

References

{{DEFAULTSORT:Automatic Proofreader Apple II software Atari 8-bit family software VIC-20 software Commodore 64 software Commodore 128 software