Date   : Thu, 21 Feb 2008 08:35:13 +0000 (WET)
From   : PCOGHLAN@... (Peter Coghlan)
Subject: BASIC error message - "Mis..."?

>
>> >  ISTR that CTRL-C clears this condition or pressing SHIFT allows the
>> >  screen print to continue.
>
>> I'm fairly certain that the SHIFT thing only relates to when screen
>> paging is turned on.
>
>No, Martin was correct, it also represents a buffer full condition.
>For example with a speech interface installed
> REPEAT:SOUND-1,160,0,0:UN.0
>you'll see the shift lock LED pulse at the end of each word (pretty much),

There are two different issues here relating to shift and shift-lock.

When the screen is in page mode (due to pressing CTRL-N or issueing VDU 14 IIRC),
pressing shift allows more lines to be displayed. Page mode is unlikely to be
the problem here because (again IIRC), page mode does not cause the display
to pause in the middle of a line, only at the end of a line.

When a buffer becomes full (including printer, sound, speech, serial and possibly
others I think), the OS illuminates both the caps lock and shift lock LEDs and
whatever operation is using the buffer is held up until space appears in
the buffer.
If caps lock is already on which it usually is, only shift lock will be noticed
lighting up. Again IIRC, the buffer full condition does not cause the LEDs to be
illuminated at full brightness so for example if you see the shift lock LED
coming
on, pressing the shift lock key will cause it get somewhat brighter. Perhaps the
lesser brightness is achieved by pulsing the LEDs? (in addition to any pulsing
due
to buffers filling and quickly regaining space).

If there are difficulties emptying a buffer due to lack of hardware etc, the
easiest way to temporarily get past a buffer full situation is to press the
escape
key. If the printer buffer was the buffer in question, issueing a CTRL-C
or a VDU 3
should then disable printing and stop the buffer filling quickly again. If it was
the serial buffer, issueing *FX3 might help, again after pressing escape.

Another related issue is that it is possible to halt screen output at any point
by pressing the CTRL and SHIFT keys together. If there is a possibility that
these
keys are being erroneously detected, this might be what is stopping the screen
output.

Regards,
Peter.