Category : C++ Source Code
Archive   : TI1170.ZIP
Filename : TI1170.ASC

PRODUCT : Borland C++ NUMBER : 1170
VERSION : 3.1
OS : DOS
DATE : January 6, 1993 PAGE : 1/3

TITLE : Solving keyboard conflicts with using the IDE.






QUESTION:
========
Sometimes when using the arrow keys in the IDE I get strange
effects, such as the shift key getting stuck on (so that
everything comes out in capitals) or perhaps numbers come out
sometimes. I see things like going through text with an arrow
key and then sometimes it starts to highlight everything. Why is
this happening and what can I do about it?

ANSWER:
=======
When you use the computer's keyboard, 1 or 2 or 4 interrupts
are generated when the key goes down, and also when the key goes
up. The machine tries to figure out from the scan codes what key
was hit, and what action to take on it.
Upon occasion, for various reasons, some of these interrupts
may not be responded to and some of the scan codes may be lost.
If some of the scan codes are lost, an arrow-key keystroke may
look to the machine like a number key, or like a shift key going
down (and not coming back up). So when the machine sees the
shift key going down, it assumes you are holding it down, so your
arrow looks like a shift-arrow and the block should be
highlighted. Or you may type in capitals when you did not intend
to.



QUESTION:
=========
So why are the interrupts not being responded to?

ANSWER:
=======
Because one scan code has not been dealt with by the time
the next one comes along. The IDE traps the interrupt and it has
a fair amount of processing to do; other TSR's that also deal
with the keyboard (anything that responds to a hotkey or changes
the way the keyboard works, like DOSKEY) slow down the keyboard
response. Your expanded memory manager, such as EMM386 or QEMM,
also has a role to play; the IDE has to switch modes from














PRODUCT : Borland C++ NUMBER : 1170
VERSION : 3.1
OS : DOS
DATE : January 6, 1993 PAGE : 2/3

TITLE : Solving keyboard conflicts with using the IDE.




protected to real mode to handle the key and it must do this
through the expanded memory manager if the latter is present.
The number of interrupts coming in also makes a difference.
The arrow keys usually generate 4 interrupts per keystroke (2
down, 2 up) but when NUMLOCK is on, they generate 8 interrupts
per keystroke. So one solution is to take NUMLOCK off, or simply
to reduce the repeat rate.
Your hardware also makes a difference. Your keyboard should
not be sending more keystrokes until the previous one has been
acknowledged but unfortunately not all keyboards behave that way.



QUESTION:
=========
Just tell me what I have to do.

ANSWER:
Short term solutions:
> When the shift state gets toggled, just tap the shift
key to reset it.
> Turn off NUMLOCK.
> Use the keypad arrow keys instead of the extended arrow
keys.
> Use the /IA and /U8 (Ignore A20 and Unusual 8042)
options with QEMM.
> Take out your expanded memory manager entirely.
> Take out TSR's that use hotkeys or change the behavior
of the keyboard, such as DOSKEY. (4DOS or NDOS is
recommended if you like DOSKEY's features.)
> Slow down your keyboard autorepeat (often settable in
CMOS BIOS options) or take out a utility that speeds up
the keyboard repeat.

Longer-term solutions:
> Try a different keyboard. Borrow a friend's, and see
if you get better results. If that helps, consider
upgrading to that style of keyboard.
> Try a different BIOS (BIOS upgrades run less than $50,
and may give you additional features) or change the
keyboard BIOS.















PRODUCT : Borland C++ NUMBER : 1170
VERSION : 3.1
OS : DOS
DATE : January 6, 1993 PAGE : 3/3

TITLE : Solving keyboard conflicts with using the IDE.




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