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horga83 / h19term

H19 terminal emulator package in python
GNU Lesser General Public License v3.0
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Destructive tabs? #10

Open hackerb9 opened 2 years ago

hackerb9 commented 2 years ago

Did the h19 terminal have destructive tabs? That is, when a tab passed over existing characters, did it blank them out? The terminfo database says that it did not, which would make some sense since the VT52 did not.

However, both the machine I am trying to evaluate for h19 compatibility (TRS-80 Tandy 200) and h19term.py have destructive tabs. Could you please clarify which behaviour is correct?

If you do not know off-hand, here is a simple way to test on a genuine h19:

printf "     nondestructive tabs\r\t\n"

Thanks!

hackerb9 commented 2 years ago

I just tried the emulated h19 in MAME and it seems to be nondestructive. That would seem to indicate the destructive tabs in h19term.py is a bug.

I typed directly into the terminal, hit ^M to go to the beginning of the line, then hit Tab. As you can see from the screenshot, the letters before the cursor did not get erased.

0000 h19.zip

horga83 commented 2 years ago

Ok thanks, I'm super busy for the next few weeks, What does the H19 manual say about tabs?

George

On Tue, 2022-10-18 at 17:31 -0700, hackerb9 wrote:

I just tried the emulated h19 in MAME and it seems to be nondestructive. That would seem to indicate the destructive tabs in h19term.py is a bug. I typed directly into the terminal, hit ^M to go to the beginning of the line, then hit Tab. As you can see from the screenshot, the letters before the cursor did not get erased. h19.zip 0000 — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you are subscribed to this thread.Message ID: @.***>

hackerb9 commented 2 years ago

The manual I found doesn't say.

“TAB - Software controlled to move the cursor to the next tab stop (eight character spaces) to the right. The tab stops are fixed at 9,17,25,33,41,49,57,65, and

  1. If the cursor is at character position 73 through 79, it will only move one character position to the right each time you type the TAB key. If the cursor is at character position 80, it will not move when you type the TAB key (unless the wrap-around feature has been selected).”

The only other references to TAB in the manual simply state that it is equivalent to CtrlI and that its octal and ANSI code are 011.

By the way, it took me a while to find any H19 user manual as a lot of the old links are dead or only have the schematics. I'm attaching the one I did find here as I expect it will be useful for h19term.

Heath Z19 Terminal Operating Manual.pdf