I'm using TK4- on Linux, with x3270 as the terminal emulator.

When I press the "Insert" key to go into insert mode, it almost never works (it may have worked 3 times for me in total). In all other cases, the x3270 terminal displays X in the bottom, and then hangs until I press "Reset".

Is there a way to fix this? Not being able to insert text can be quite frustrating after a while.

Thank you. So if I'm understanding this correctly, most screens (especially the editor) pre-fills fields with spaces all the way to the end, and x3270 will not let you insert a character if it would mean that it would push something over the edge so to speak.

There seems to a few fields that does not behave this way, and those are the cases when I noted that Insert worked.

If I understand how the 3270 terminal works, all of this is client side? I'm asking, because if it is completely client-side, then I should be able to modify x3270 so that it allows inserting more text than the field allows (deleting the characters that gets pushed to the right side).

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Some 3270 terminal emulator programs allow characters to be inserted in a field even if it is padded with trailing blanks instead of trailing nulls.? Check the option settings for your terminal emulator.

Back in the 1980's, when I was using a real 3277 terminal all day long, this was one of my biggest gripes about the way the hardware worked.? Here was the typical sequence of events:
* Hit the tab key to move to the field where I want to insert something at the beginning of the field.
* Press the Insert key
* Type the character I want to insert.? Instead, the keyboard just locks up.
* Press the Reset key to unlock the keyboard.
* Hold down the right cursor key to move the cursor past the last non-blank character in the field.? This was a tiresome process because the key repeat rate on those old 3277 terminals was really slow, something like 3 characters per second.
* Hit the Erase EOF key to inset nulls from that point to the end of the field.
* Press the back tab key.? For some reason, moving the cursor backwards to the previous tab position seemed to be a painful process for the 3277 hardware.? The screen would flicker and the CRT screen would emit some strange, high-pitched noises and eventually the cursor would move to the beginning of the field.? Pressing a forward tab key gave a very quick, smooth response, but a backward tab was a different story.
* Press the Insert key (again, because pressing the Reset key to unlock the keyboard also turned off the insert mode.)
* FINALLY, type the character I want to insert and watch it actually get inserted.? (Whew!)

When the team of programmers at the IBM Yorktown research laboratory wrote the MYTE terminal emulator program for the PC, which evolved into the PCOMM 3270 program product, this was probably the first characteristic of the 3277 terminal that they decided NOT to emulate.

Charles Bailey

On 2019-11-08 1:21 AM, Elias M?rtenson wrote:

When I press the "Insert" key to go into insert mode, it almost never works (it may have worked 3 times for me in total). In all other cases, the x3270 terminal displays X in the bottom, and then hangs until I press "Reset".

Is there a way to fix this? Not being able to insert text can be quite frustrating after a while.

As others have said, it's all about the difference between blanks or spaces (x'40' in EBCDIC) and "nulls" (x'00' being the NUL character).

When a field is full and you want to insert something, the usual procedure is to use the DEL button to delete characters where the cursor is, which causes characters after that location to shifted left one position, and the last location within that field is replaced by a x'00' or NUL or "null" character.

Sometimes you can fast-track the deletion of characters by finding a place in the field where all characters after that place can be deleted.? After you have moved the cursor to that place, you can use the Erase-EOF (erase to end-of-field) key that Joe mentioned. Usually this is mapped to the End key on a PC, though I have seen it mapped to Ctrl-E.

In IBM's ISPF editor, as Fish says, you can issue the NULLS ON and NULLS OFF commands.? NULLS ON refers to changing the blanks after the last non-blank in the display of edit records to nulls so there is room to insert new data using insert-mode.? NULLS ON STD refers to leaving the first character after the last non-blank as an actual blank, before converting the rest of the trailing blanks to nulls. NULLS ON ALL refers to not having this non-null blank after the last non-blank.? Note that this is only a screen handling change - the data in the records being edited will still be deemed to be blanks by the editor, and so blanks (not nulls) will be written to the data set when the data is saved.

When I used to use real 3270 terminals, I always used NULLS ON so I could more easily insert stuff.? The downside of this is sometimes I would just move the cursor to where I wanted the text and type it in, but then when I pressed Enter, the text I typed collapsed left to abut previous non-blank data because I had not overlaid the preceding nulls with blanks.? In normal terminal I/O, nulls are not sent inbound to the host, so you can see why the editor was not aware of where I had really placed my new text.? At least with NULLS ON STD, there was at least one blank before my new text.

On a 3277, INSERT MODE stayed on when hitting Enter (or a PF key), but it was reset by Enter (and PF keys) on later terminals.

With 3270 emulators on PCs, I now always use NULLS OFF, because the PC software is now smart enough to let the user? insert data when the only non-null data being lost as a result is blanks.? Further, when I move the cursor to where I want the text to be, with NULLS OFF I don't get any "collapse left" surprises when I enter new text.? This is the behaviour that I think Tony was referring to because the PC software has decided to deviate from actual 3270 hardware behaviour in order to improve usability.

As well as using Reset to get out of Insert Mode, some emulators will use the Insert key as an Insert Mode toggle switch.

I expect I've managed to confuse the issue even more...

Cheers,
Greg

On Sun, 2019-11-10 at 22:35 +1100, Grog Proce wrote:

As others have said, it's all about the difference between blanks or
spaces (x'40' in EBCDIC) and "nulls" (x'00' being the NUL character).

Thank you very much for this information. It's all clear to me now, and
it explains precisely the behaviour I have been seeing.

I also installed Brexx, which allows me to use its FSS library to
create my own screens. That helped be further to understand its
behaviour.

With 3270 emulators on PCs, I now always use NULLS OFF, because the
PC
software is now smart enough to let the user insert data when the
only
non-null data being lost as a result is blanks.

Sadly, x3270 doesn't seem to behave this way. I'm considering
implementing this behaviur in it myself. It shouldn't be too hard.

As well as using Reset to get out of Insert Mode, some emulators
will
use the Insert key as an Insert Mode toggle switch.

x3270 also doesn't behave this way. It seems to be a pretty accurat
eemulation of the absolute oldest 3270 models. :-)

I expect I've managed to confuse the issue even more...

Not at all. It's crystal clear. Thanks to you and all others who has
replied.

Regards,
Elias

I have installed WC3270, This emulator executes the Insert key as expected.
If I use NULLS in RPF, I can insert characters in the line if the line contains trailing "blanks".
I change in RPF the blanks after the last non-blank character into NULLS (x'00')
With the NONULLS command I cannot insert characters unless I delete some characters
with the DEL key. This works as designed.

However, If I use Tom Brennan's Vista TN3270, you can always Insert characters if there
are blanks after the last non-blank character.
It does not matter if the editor is in NULLS mode or not.
Even in ISPF with NULLS OFF I can insert characters.

I realize that this is not standard, but I do appreciate this "feature".
Cheers,
Rob

Hi Elias,

WC3270 is the Windows equivalent of X3270.
Vista TN3270 is a Windows program.

You can download the latest version of X3270 ,

Cheers,
Rob

On 11/19/19 9:54 PM, Elias M?rtenson wrote:

As would I, but sadly it seems as though none of these applications are available for Linux.? The only alternative really seems to be x3270, which is indeed quite limited, with the most archane of UI's. I should really fork it and implement these features.

Tom Brennan's Vista TN3270 runs under Wine on Linux just fine.

Elias, have you tried using the x3270 menu "Options -> Toggle -> Blank Fill" ?

From the? :

Blank FillIf set, x3270 behaves in some un-3270-like ways. First, when a character is typed into a field, all nulls in the field to the left of that character are changed to blanks. This eliminates a common 3270 data-entry surprise. Second, in insert mode, trailing blanks in a field are treated like nulls, eliminating the annoying `lock-up' that often occurs when inserting into an field with (apparent) space at the end.I'm also surprised of your statement about x3270, "quite limited, with the most arcane of UI's."

Besides x3270 on Linux, on Windows I'm also using Attachmate's Reflection and IBM's PCOMM products, but somehow I like wc3270 on Windows better -- which is effectively x3270 on Windows. All x3270 variants free, not so Reflection or PCOMM. ?

Cheers,

Peter

Elias,?

Have you tried the x3270 menu "Options -> Toggles -> Blank fill" ?

From the? :

Blank FillIf set, x3270 behaves in some un-3270-like ways. First, when a character is typed into a field, all nulls in the field to the left of that character are changed to blanks. This eliminates a common 3270 data-entry surprise. Second, in insert mode, trailing blanks in a field are treated like nulls, eliminating the annoying `lock-up' that often occurs when inserting into an field with (apparent) space at the end.Cheers,

Peter