[hercules-os380] DEL vs INS

[[e-mail] [hercules-os380]]

Why is there an ASCII code (0x7f) for "DEL"
but there is no code for "INSERT"? And
page up and page down too.

Thanks. Paul.

['Dave Wade' [e-mail] [hercules-os380]]

-----Original Message-----
Sent: 09 November 2018 09:30
Subject: [hercules-os380] DEL vs INS
Why is there an ASCII code (0x7f) for "DEL"
but there is no code for "INSERT"? And
page up and page down too.

If by ASCII you mean IA7, well it was a teletype code. Those actions are not meaningful on a TTY with a roll of paper...
... nor being an American code are there ASCII codes for £ or € which are pretty useful these days...

Thanks. Paul.

Dave

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Post by ***@yahoo.com.au [hercules-os380]
Why is there an ASCII code (0x7f) for "DEL"
but there is no code for "INSERT"? And
page up and page down too.

If by ASCII you mean IA7, well it was a
teletype code. Those actions are not
meaningful on a TTY with a roll of paper...

I see. They are also not meaningful in a
text file. But they are keys on my keyboard.

I am wondering whether character codes
greater than decimal 127 should be
repurposed to encode PgUp, Insert, F1 etc,
or whether they should generate ANSI
escape sequences which is what I
currently see happening when I use
telnet. I notice that the "DEL" key has an
ANSI sequence as well, it doesn't
generate x'7f'. I also notice that there is
a full 24 function keys, using shift.

I don't see the codes listed here though:

https://en.wikipedia.org/wiki/ANSI_escape_code

e.g. page up I am seeing as ESC [ 5 ~
and page down is ESC [ 6 ~

An interesting code is 5 on the numeric
keypad when num lock is off, which is
ESC [ G
I don't know what that means. I know
what the other keys are, e.g. "8" is
cursor up.

.. nor being an American code are there
ASCII codes for £ or € which are pretty
useful these days...

Those characters are not on a US ASCII
keyboard and I believe should instead
be written as GBP$100 and EUR$100.

BFN. Paul.

['Fernando M. Roxo da Motta' [e-mail] [hercules-os380]]

Post by ***@yahoo.com.au [hercules-os380]
Why is there an ASCII code (0x7f) for "DEL"
but there is no code for "INSERT"? And
page up and page down too.

Perhaps because ASCII was created in times of paper TTY?

Usually text editors at that time behaved much like linux/unix ed(1) and
those codes (insert, page up and page down) didn't made any sense?


Cheers.

Post by ***@yahoo.com.au [hercules-os380]
Thanks. Paul.
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[Joe Monk [e-mail] [hercules-os380]]

Because ... in the glory days of computing, we used paper tape. There were
7 punches on paper tape. 7 1s = 127, and since all 7 were punched, that
means ignore, aka delete. It was the original way of fixing a bad punch on
paper tape.

Joe

Post by ***@yahoo.com.au [hercules-os380]
Why is there an ASCII code (0x7f) for "DEL"
but there is no code for "INSERT"? And
page up and page down too.
Thanks. Paul.

[[e-mail] [hercules-os380]]

Post by Joe Monk ***@gmail.com [hercules-os380]
Because ... in the glory days of computing, we
used paper tape. There were 7 punches on paper
tape. 7 1s = 127, and since all 7 were punched,
that means ignore, aka delete. It was the original
way of fixing a bad punch on paper tape.

Thanks for the pointer! Based on what you
said I did a google search and found this:

http://wiki.c2.com/?PaperTape

When punching information on a paper tape, whenever the user noticed an error, they would delete the bad character by pressing the DEL key on the keyboard. This worked by backspacing the tape and punching a frame of all 1's on top of the holes of the bad character. When reading the tape, the tape reader would simply skip any frame of all 1's.


My next question - when were parity bits used,
and do we lose anything by moving from 7-bit
ASCII to 8-bit ASCII++?

Thanks. Paul.

[Vince Coen [e-mail] [hercules-os380]]

Hmm, this is testing my memory a bit -

Parity has always been present since 6 holes, the number of bits in a
EBCDIC character is not aligned.

I worked on kit (ICT/ICL 1900) that used paper tape that used a 6 bit
characters with 24 to a word which is not the same thing as on a 360 +.

I think IBM 1401 was another odd one and I am too tired to open my large
cupboard with books and manuals to check, plus there is a ton of stuff
in front of it.

It was only a few years ago that I came across mine going back to the
70's along with the hand card punch and a full box of card chard covers
(cover up a bad punch selection) as there was always a shortage of
machine that could update an existing card to a fresh one (had two card
slots sort of). Reason getting a deck of cards punched from the punch
input team (forgot the name of 'em) was always slow, i.e., days - so
programmers became very good at touch typing on the card key punch
machines from both IBM and ICL that was stored in an area for the purpose.

It was a great day when MOP (ICL) and TSO came about as we could key
directly into the system/s.


Vince

Post by ***@yahoo.com.au [hercules-os380]

Post by Joe Monk ***@gmail.com [hercules-os380]
Because ... in the glory days of computing, we
used paper tape. There were 7 punches on paper
tape. 7 1s = 127, and since all 7 were punched,
that means ignore, aka delete. It was the original
way of fixing a bad punch on paper tape.

Thanks for the pointer! Based on what you
http://wiki.c2.com/?PaperTape
When punching information on a paper tape, whenever the user noticed
an error, they would delete the bad character by pressing the DEL key
on the keyboard. This worked by backspacing the tape and punching a
frame of all 1's on top of the holes of the bad character. When
reading the tape, the tape reader would simply skip any frame of all 1's.
My next question - when were parity bits used,
and do we lose anything by moving from 7-bit
ASCII to 8-bit ASCII++?

[Mike Schwab [e-mail] [hercules-os380]]

Actually, mainframes preceding IBM 360 used 6 bit characters with 7th
bit parity on 7 track tapes. These could still be read on the IBM
360/370+ with bus and tag drives, but the 3420 and up were 8 bit
EBCDIC with 9th bit parity on 9 track drives. Cartridges went to 18
and 36 bit widths.

PCs and such used the 128-255 range for graphics and characters +
diacritical marks. This was dropped for UTF-8 and the characters
moved to multi byte characters.

Post by ***@yahoo.com.au [hercules-os380]

Post by Joe Monk ***@gmail.com [hercules-os380]
Because ... in the glory days of computing, we
used paper tape. There were 7 punches on paper
tape. 7 1s = 127, and since all 7 were punched,
that means ignore, aka delete. It was the original
way of fixing a bad punch on paper tape.

Thanks for the pointer! Based on what you
http://wiki.c2.com/?PaperTape
When punching information on a paper tape, whenever the user noticed an error, they would delete the bad character by pressing the DEL key on the keyboard. This worked by backspacing the tape and punching a frame of all 1's on top of the holes of the bad character. When reading the tape, the tape reader would simply skip any frame of all 1's.
My next question - when were parity bits used,
and do we lose anything by moving from 7-bit
ASCII to 8-bit ASCII++?
Thanks. Paul.
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Yahoo Groups Links

[[e-mail] [hercules-os380]]

Post by ***@yahoo.com.au [hercules-os380]
This worked by backspacing the tape and
punching a frame of all 1's on top of the holes
of the bad character.

If you need to delete the last 2 characters,
could you just press DEL twice?

And I guess to go forward you can type
any character, because it doesn't make
any difference.

BFN. Paul.

[Gerhard Postpischil [e-mail] [hercules-os380]]

Post by Joe Monk ***@gmail.com [hercules-os380]
Because ... in the glory days of computing, we used paper tape. There
were 7 punches on paper tape. 7 1s = 127, and since all 7 were punched,
that means ignore, aka delete. It was the original way of fixing a bad
punch on paper tape.

I must have missed the glory days. <G>

A Navy contract I worked on used Mylar tape to bootstrap a CDC 160.

Gerhard Postpischil
Bradford, VT


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