107 lines
5.3 KiB
Plaintext
107 lines
5.3 KiB
Plaintext
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ASCIICOD.TXT
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By Aaron Priven
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This is a little text file for all of the novices out there like myself
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who have wandered in on the world of computing eager for knowledge but
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who have found very little. This is a table of the ASCII codes.
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"What? you ask? The ASCII codes? Why that's easy. 32 is space, and 33 is
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the exclamation point, and 34 is the double quote..." All true, except that
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the code starts at 0. Well, I imagine that all of you have heard of "NUL"s
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or null characters, and probably "NAK"s (which are used in Xmodem Checksum
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protocol) but what are the other mysterious codes between 0 and 32?
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Well, friends, this is your opportunity to find out. Because I am going to
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tell you. Now don't get the idea that I have been in the computer business
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since 1956 and was on the committee that invented the ASCII codes. I wasn't
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born till 15 years after that and I got interested in computers two years ago.
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I simply stumbled on this very interesting table in the VisiFile manual
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(a very bad program marketed by the late lamented VisiCorp that came with my
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computer) that not only included the number and two- or three-letter
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mnemonic (a fancy "computerish" word for name) but what the codes were
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actually intended to do! (Yes, it sounds too good to be true.) So I decided
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to gift you all with this table.
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Oh, if you think this is stealing their manual material, for one thing
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the ASCII codes are far from copyrighted. And VisiCorp is but a small part of
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data in the computer-industry's (read-only?) memory.
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And heeeeeeeere's Tabley:
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------------------------------------------------------------------------------
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CODE NUMBER MNEMONIC WHAT THE HECK IT DOES
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------------------------------------------------------------------------------
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00 NUL Null character (nothing)
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01 SOH Start heading
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02 STX Start of text
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03 ETX End of text
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04 EOT End transmission
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05 ENQ Enquiry
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06 ACK Acknowledge (We heard you and yes.) See NAK
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07 BEL Bell (BEEEEEEP!)
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08 BS Backspace
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09 HT Horizontal tab
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10 LF Line feed
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11 VT Vertical tab
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12 FF Form feed (clear screen)
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13 CR Carriage return (enter)
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14 SO Shift-out
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15 SI Shift-in
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16 DLE Data link escape (I don't know what this is either)
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17 DC1 Device control #1(maybe they ran out of things to do?)
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18 DC2 Device control #2
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19 DC3 Device control #3
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20 DC4 Device control #4
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21 NAK Negative acknowledge (We heard you, but no.) See ACK
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22 SYN Synchronous idle (let's sit around doing nothing)
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23 ETB End transmission blocks (whatever that means)
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24 CAN Cancel (Whoa, Nellie!)
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25 EM End medium (kill that conjurer!)
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26 SS Special sequence
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27 ESC Escape
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28 FS File separator
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29 GS Group separator
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30 RS Record separator
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31 US Unit separator
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32-126 -- Normal characters --
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127 DEL Delete
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------------------------------------------------------------------------------
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The parts in parentheses are my own little comments, or explanations.
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I still don't know what some of them (the codes) mean. The other thing one
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must remember is that these were originally for teletypes and not computers,
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so that way "Synchronous idle" and the "Acknowledge" family make more sense.
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SYN means that someone doesn't want to do anything just yet. ACK and NAK are
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in response to a question. ACK means "Yes, we heard you, and the answer is
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yes." NAK means "Yes, we heard you, but the answer is no." Presumably if the
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questioner recieves anything else then the questioner means "What?"
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Other ones that make sense to me but might not to other people: ENQ was
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more than likely the thing people sent when they wanted an ACK or NAK.
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BEL is a bell because electronic speakers on teletypes were not common.
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VT probably meant "Go to the next vertical tab row" just as a normal
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tab means "Go to the next tab column." FF means to go to the next page;
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because there are no pages on a video screen it is interpreted to mean
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"Clear the screen." I'm not sure what SI and SO are supposed to do. I
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doubt if people would have bothered with other typefaces or compressed
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type on the old teletypes. DCx probably means they had four characters
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to fill so they put in something meaningless like "Device controls."
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"End medium" is a complete mystery to me. SS is of course for codes
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relating to things they hadn't thought of at the ASCII committee.
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FS,RS,US,and GS I should think would be for a database, but they
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didn't put databases on teletypes did they? And why they made DEL all
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the way back in the end when they could have just eliminated DC4 or something
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is beyond me.
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Aaron Priven
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If you like this text file, please send 10 cents to the above address.
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Aaron Priven
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540 Sylvan Avenue
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San Mateo, CA 94403-3214
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U.S.A.
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Foriegn currency accepted!
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e address.
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