SWAT (Strategic Weapon Against Typos)

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Name SWAT (Strategic Weapon Against Typos)
Ontology
Released 1982

SWAT (Strategic Weapon Against Typos) by Jon Voskuil and Alan J Zett is a type-in program checker for Apple II, Atari and TRS-80 used by SoftSide magazine.

It generates a table with three columns: a range of line numbers, a two-letter 'SWAT Code', and the length (in bytes) of the specified program lines.

This narrows the area of a bug to no more than twelve lines or no more than about 500-700 bytes of code.

The 'resolution' of SWAT can be increased for particularly error-prone code. For instance, change "NU=12: B=500" to "NU=5: B=200" to provide a checksum for every 5 lines or 200 bytes of code.

The SWAT Code is generated by adding up the value of every byte in a chunk and then converting to a base-26 number. Just the two rightmost 'digits' (letters) are used. This approach leaves it vulnerable to transposition errors.


Sample Output

Swat.gif SWAT

Swat-modified parameters.jpg SWAT with modified parameters


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