dec_radix_50.rb

Encodes strings to the DEC Radix-50 encoding.

RADIX 50 is an uppercase-only character encoding created by Digital Equipment Corporation (DEC) for use on their PDP, and VAX computers. RADIX 50's 40-character repertoire (050 in octal) can encode three characters into one 16-bit word (PDP-11, VAX). It was also adapted for use on the Soviet PDP-11 clones, notably the Elektronika MK90 portable computer.

The actual encoding differs between the systems.

Learn more on the Wikipedia.

Installation

Add this line to your application"s Gemfile:

gem "dec_radix_50"

And then execute:

$ bundle install

Or install it yourself as:

$ gem install dec_radix_50

Usage

Encoding

DECRadix50.encode(charset, string [, replace_char]) => Array<Integer>

Arguments

• charset: character set, should be 40 characters long for the DEC RADIX-50. The charset string length defines the base.

  The gem comes with two predefined characters sets:

  # Elektronika MK90 filenames charset:
  MK90_CHARSET = " ABCDEFGHIJKLMNOPQRSTUVWXYZ$./0123456789"
  
  # RT-11 filenames charset:
  RT11_CHARSET = " ABCDEFGHIJKLMNOPQRSTUVWXYZ$%*0123456789"

• string: string to encode.

• replace_char: replaces unsupported characters in the input string. Should be included in the charset. Default value is " " (a space).

Returns

• Array of integers.

Example:

require "dec_radix_50"

DECRadix50.encode(DECRadix50::MK90_CHARSET, "ABCDEF")
# => [1683, 6606]

Decoding

DECRadix50.decode(charset, encoded_values) => String

Arguments

• charset: character set, should be 40 characters long for the DEC RADIX-50. The charset string length defines the base.

• encoded_values: array of integers that represent an encoded string.

Returns

• String.

Example:

require "dec_radix_50"

DECRadix50.decode(DECRadix50::MK90_CHARSET, [2092, 1015, 34_320, 3259, 8001, 29_000, 3412, 24_567, 815, 859, 0])
=> "ALL YOUR BASE ARE BELONG TO US   "

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/8bit-mate/dec_radix_50.rb.

License

The gem is available as open source under the terms of the MIT License.