>>Someone asked the question about what good are reading tapes NL. >>There are valid reasons and these go back to the early years before >>diskettes, etc, when people wanted to tansfer data. Early, early on >>the universal mode of transfer was 7-track tape, BCD, Even-parity >>with no labels.
> Even parity universal? I'm practically positive that you go back to > the 7090 and 7094, where odd parity was the norm. For NRZI, which was common before phase encoding of 1600BPI, odd parity is best. I believe, though, that even parity was all to common for 7 track tape. With even parity, one can't write the character with all bits zero, as it results in no magnetic transitions on the tape. A character is recognized by at least one track having a magnetic transition. I don't know specifically which systems allowed/used even parity seven track, but I do recall that it was used. -- glen ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
