| 摘要 |
Incoming data from one of two data channels is coupled through a multiplexer to a ping pong memory. While data is being read into one section of the ping pong memory from the data processing equipment, it is being read out of the other side of the ping pong memory. Since part of the header information constitutes marks and spaces, i.e., groupings of all ones or all zeros, if a data word contains all ones, it could be misconstrued. Therefore, any data word which contains all ones is converted to a data word which is one bit less than all ones. Once this conditioning is done, of each group of 13 input words, each word representing a pixel and each word being ten bits long, the first, fifth, and ninth words are extracted using programmable logic arrays. The 30 bits obtained by this extraction are broken down and appended, in groups of three, to the existing bits of the remaining ten words of each group of 13 input words. This then results in ten 13-bit words and achieves optimum packing utilizing all 13 channels on the tape.
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