Micro UK101: Backspace / "Rubout" action

[jonb]

Hello

Very happy to report that I think I know what is wrong with my Micro UK101 which kept failing to operate for some reason. I think it is all down to using three AA cells for power. I connected a "proper" power supply to it today and it's working nicely.

I also have a Wyse 120 terminal which plugs in and I can enter and run BASIC programs. So far, so good.

However, there is no way to backspace; that is, emulate the "rubout" key of the UK101, unless you know better!

I'm suspecting that some sort of ROM hackery will be needed to map BS to RUBOUT in some way. This is pretty much out of my league at the moment! So the questions:

Is this do-able or has anyone done it?
Does EhBASIC support backspace? (actually, PET style screen editing would be really nice but I think it'd be hard without a dedicated memory mapped display like the PET has).

Cheers

JonB

[jonb]

Interestingly, the CEGMON manual says that RUBOUT equates to $5F so if I can map the backspace key on the Wy120 to $5F I might be onto a winner.

Of course, it would be better to get Ceggy to recognise BS instead of $5F for the rubout function!

[EDIT] D'oh! It's the underscore character. However when you enter underscore on the terminal, it comes up as entered (but BASIC acts as if you'd hit rubout, so, for example, typing PRIN_NT <CR> in BASIC makes it print a blank line as if you'd entered PRINT).

Reading further into the Ceggy manual (here: http://uk101.sourceforge.net/docs/pdf/cegmon.pdf I can see that there is a dual cursor editor function like you have on a BBC Micro. Nice... although it won't work with a VT-100 terminal and serial port..

[BigDumbDinosaur]

jonb wrote:

I also have a Wyse 120 terminal which plugs in and I can enter and run BASIC programs. So far, so good.

However, there is no way to backspace; that is, emulate the "rubout" key of the UK101, unless you know better!

I can't vouch for the WY120 (never used it), but the WY60 family supports control key remapping through the setup screens. The following instructions should work with the WY120 if it is running in WY60 emulation. It is assumed that you have the WYSE ASCII keyboard. Keytop names may be slightly different if you are using the ANSI or PC-style keyboard.

1. Enter the terminal's setup screen. The method varies according to the keyboard used.
2. Switch to the function key setup screen.
3. Hold down Ctrl (control) and press Backspace.
4. In the input field for the key, which initially should be blank, type Backspace followed by Esc, followed by W. This will cause Backspace to emit $08 $1B $57 when typed, causing a destructive backspace or "rubout." DO NOT type anything else in this field. If you mistype, use the left-arrow key (cursor left) to erase.
5. Exit setup, saving your changes.

[jonb]

Sorry BDD it's doesn't work... In fact it has no effect. I think it will be necessary to fix it in the ROM, although I have no idea how to. As I wrote earlier, the underscore does act as a delete to the BASIC interpreter, but it doesn't look like it on screen.

Thanks for your advice!

JonB

[Tor]

I don't know about the UK101 or its BASIC, but it was common to use underscore as a delete indicator some decades ago. That was the only way to visibly "edit" something on a paper-printing TTY. So the 'delete' key would simply print an underscore and you mentally removed as many previous letters as there were underscores. So your example of PRIN_NT (or e.g. PRJM__INT) would be what was printed on the TTY and you would know that your line-editor now held 'PRINT' in memory. IIRC the first line-oriented editor I used on the old Norsk Data NORD-10 back in 1982 worked that way even on a fully backspace-capable CRT monitor like the VT100.

A remnant of that idea could be seen on early Unix systems, and even up to this day with some shells and/or terminal modes.. using ctrl-H as a delete character would literally print ^h on the screen instead of backspacing over the character which was deleted. And for that reason you see the how people use ^h^h as a toungue-in-cheek way of indicating that they could have said something else.. 'this terr^h^h^h^hnice car', for example.

-Tor