[comp.sys.ibm.pc] Problems with Compaq SLT/286 and QuickBasic 4.5

marks@cs.keele.ac.uk (Mark Scase) (10/31/89)

I have a problem when running Microsoft Quickbasic 4.5 (don't
laugh) on my Compaq SLT/286 model 40.  Incidentally, the
Compaq is running Compaq DOS 4.01.
This problem occurs only when the Compaq is battery powered and
never when the machine is powered by the AC adaptor.
When I try to run or compile a BASIC program from within the
integrated development environment of Quickbasic the screen
of the Compaq turns completely white and therefore no characters
are visible.  The SLT/286 does not hang up - only the screen is
affected - but with nothing appearing on the screen the machine
is not that useful.  If I press the appropriate keys I can exit
from Quickbasic and return to DOS (still with the screen whited
out).  If I then run any other program which uses graphics then the
screen of the SLT/286 returns to normal.  Therefore it appears
that somehow Quickbasic is turning the SLT/286 into graphics
mode at an inappropriate time.
This effect happens no matter what BASIC program is loaded into
Quickbasic and, I repeat, only happens when the SLT/286 is under
battery power.
I have contacted Microsoft and Compaq and they blame each other!
I am not running any memory resident programs at the same time
which might upset Quickbasic.
Has anyone on the net experienced similar problems?
Any advice would be appreciated.

Mark Scase
Department of Communication & Neuroscience
University of Keele, UK.
coa44@uk.ac.kl.seq1   or  marks@uk.ac.kl.cs

philba@microsoft.UUCP (Phil Barrett) (11/03/89)

In article <1128@kl-cs.UUCP> marks@cs.keele.ac.uk (Mark Scase) writes:
>I have a problem when running Microsoft Quickbasic 4.5 (don't
>laugh) on my Compaq SLT/286 model 40.  Incidentally, the
>Compaq is running Compaq DOS 4.01.
>This problem occurs only when the Compaq is battery powered and
>never when the machine is powered by the AC adaptor.
>When I try to run or compile a BASIC program from within the
>integrated development environment of Quickbasic the screen
>of the Compaq turns completely white and therefore no characters
>are visible.  The SLT/286 does not hang up - only the screen is
>affected - but with nothing appearing on the screen the machine
>is not that useful.  If I press the appropriate keys I can exit
>from Quickbasic and return to DOS (still with the screen whited
>out).  If I then run any other program which uses graphics then the
>screen of the SLT/286 returns to normal.  Therefore it appears
>that somehow Quickbasic is turning the SLT/286 into graphics
>mode at an inappropriate time.
>This effect happens no matter what BASIC program is loaded into
>Quickbasic and, I repeat, only happens when the SLT/286 is under
>battery power.

sorry, net.  I tried to send and the mail bounced.

Mark

I know precisely what the problem is.  The DACs in the SLT VGA are
turned off when running on batteries (they are wicked power suckers).
So, when an app programs the DACs, if it uses a value that it read out
of the DACs at start up time (which are FF since the DACs are off),
you get, suprise, white.  Several other apps have the same problem -
Attack Sub 688 and some `other' products.  Compaq has a little program
you can get that turns the DACs on.  I'm kind of suprised Compaq (UK?)
says this.  The Compaq US support people told me about the app.  Try again.
Probably a new support person.

Just so I don't get accused of bashing compaq -- the SLT286 is the
first laptop that I actually like.  Its a great little product.
And this turning off the DACs business was the right trade-off.

Phil Barrett

Yes, Igor, the above comments do not necessarily reflect the
opinion of my employer.