US 4,789,852 A · Method and apparatus for converting data in a binary format

Abstract

A method and apparatus for converting data in a pure binary format into a format that is transparent to a data handling system that utilizes the International Telegraphers Alphabet No. 5 (ITA 5), or the American subset thereof, the American Standard Code for Information Exchange (ASCII). The apparatus according to a specific embodiment of the present invention includes a 4 byte input register that has a parallel output, a 5 byte output register that has a parallel input and encode logic connected between the two registers. The input logic either directly connects or maps the output from the bits of the input bytes to corresponding positions in the bits of the first four output bytes, converts the data of other bits in the input bytes, or maps the bits of the input bytes into the 5th byte of the output word. The Method according to a specific embodiment of the present invention encodes data in an 8 bit byte of pure binary into the 7 bit code of the ASCII format such that only printable, and hence transparent ASCII characters are produced. The method generates five 8 bit bytes of code for every four 8 bit bytes of data by mapping the parity bits of the data into the 5th byte, testing bit positions 6 and 7 of each byte to ascertain whether they are both zeros and if so setting and mapping an indicator bit into the 5th byte for every pair of tested bytes and inverting those bits and swapping 1 bit of each of the two bytes, and then storing the manipulated bits in corresponding locations in the output word, and then finally setting the value of one or both bits 6 and 7 in the 5th byte of the output word to ensure the 5th byte is not a control character.

Claims16

Dependent claims

An automatic method for encoding an input word of binary data into an output word, the input word comprised of at least two multibit input bytes comprised in turn of a predetermined number of input bits, the output word comprised of at least the same number of multibit regular output bytes as in said input word, plus an additional multibit output byte, each regular output byte comprised in turn of a predetermined number of output bits arranged into a first group and a second group, said method comprising:

storing an input word into an input register having a parallel output;
automatically transferring unchanged in parallel the information of a first group of predetermined input bits in a predetermined order from each byte to a first group of predetermined output bits of each byte of an output word in an output register having a parallel input;
testing the information of a second group of predetermined input bits that are different from said first group and if said information is of a predetermined value, converting said informtion to a different value;
transferring either said second group of input bits or if a conversion has been done transferring the converted value of said second group of input bits in a predetermined order to a second group of predetermined output bits of the output word in said output register;
and
transferring data indicative of whether a conversion has been done into said additional byte of said output word in said output register.

3 more elements

Apparatus for encoding an input word of binary data into an output word of encoded data, the input word being comprised of at least two multi-bit input bytes, each byte having at least five bits arranged from a Least Significant Bit (LSB) to a Most Significant Bit (MSB), the output word having a predetermined format and being comprised of a plurality of regular output bytes equal in number to the number of said input bytes, each byte having at least five bits arranged from a Least Significant Bit (LSB) to a Most Significant Bit (MSB), said output word also being comprised of an additional output byte, said apparatus comprising:

an input register having a parallel output and comprised of a predetermined plurality of individual input storage cells equal in number and corresponding to the total number of bits in said input word, said input storage cells corresponding to each input byte being grouped into a first plurality of input storage cells for storing a first plurality of bits of that input byte and a second plurality of input storage cells for storing a second plurality of bits of that input byte;
an output register having a parallel input and comprised of a predetermined plurality of individual output storage cells equal in number and corresponding to the total number of bits in each output word, said output storage cells corresponding to each output byte being grouped into a first plurality of output storage cells which correspond to said first plurality of input storage cells and a second plurality of output storage cells which correspond to said second plurality of input storage cells, and a third plurality of output storage cells for storing said additional output byte;
first means for connecting said outputs of said first plurality of input storage cells in the same arrangement to said inputs of said first plurality of output storage cells;
logic means for testing said second plurality of input storage cells of each input byte for having data stored therein with a predetermined pattern of bits;
and if true, for manipulating said data stored therein, for presenting said data at a first output thereof, for generating new data indicating said manipulation, and for presenting said new data at a second output thereof;
second means for connecting said logic means first output to said inputs of said second plurality of output storage cells;
and
third means for connecting said logic means second output to said inputs of said storage cells for said additional output bytes.

5 more elements

An automatic method for encoding an input word of binary data into an output word of binary data, the input word comprised of at least two multibit input bytes that are each comprised of a predetermined number of input bits which can be grouped into at least a first group and a second group, and the output word comprised of a corresponding number of multibit regular output bytes and comprised of an additional group of output bits, wherein the term byte means a related group of a plurality of bits, said method comprising:

storing an input word into an input register;
automatically transferring in a known order the information of said first group of input bits from each input byte to known locations in an output register that holds said output word;
testing the information of each said second group of input bits from each input byte to determine if such information is a predetermined value, in which case the test results are denoted affirmative;
converting said tested information to a known value if said tested information has said predetermined value;
for each input byte transferring to known locations in said output register either the information of said second group of input bits if said information does not have said predetermined value or information having said converted known value if said information of said second group of input bits does have said predetermined value;
and
for each input byte transferring data indicative of whether a conversion has or has not taken place into said additional group of output bits, whereby the encoded word is comprised of a first set of encoded bytes each encoded byte including an encoded first group of bits and an encoded second group of bits and an encoded additional group of bits.

4 more elements

Dependencies are inferred from the claim text.

Method and apparatus for converting data in a binary format

Life of this patent

Method and apparatus for converting data in a binary format

Life of this patent

Abstract

Claims16