EMS Freeze

[Tim Camarda]

I have a customer with a Toshibia Laptop.

Using MS DOS 7.1, the EMM386 driver will load, and the fre-11 function
validates that there is EMS available for our virtual arrays.

However, any virtual arrays that we try to load data into, will
freeze DOS.

This little test program loads a string into an array, then prints DONE
when the array is loaded.
_______________________________________
$ERROR ALL

DEFINT A-Z

DIM VIRTUAL LB(0:1000000) AS STRING*12
DIM X AS QUAD

FOR X=0 TO 1000000
LB(X)=STRING$(12,"A")
REM IF INP(&H60)=1 THEN ERASE LB:END
NEXT
PRINT "DONE"
END
_______________________________________
What happens is this:

The program displays DONE, but the system is now froze, and can not
be reset by Ctrl+Alt+Del..only pwr/on/off will work.

I tried this code on a few different machines, and it of-course works properly, but
not for this Toshiba.

From my customers Laptop:

Windows Expanded Memory Driver Version 4.95
Copyright 1988-1995 Microsoft Corp.

Available expanded memory . . . . . . . . 32,76KB

LIM/EMS version . . . . . . . . . . . . . 4.0
Total expanded memory pages . . . . . . . 2,07
Available expanded memory pages . . . . . 2,04
Total handles . . . . . . . . . . . . . . 64
Active handles . . . . . . . . . . . . . 1
Page frame segment . . . . . . . . . . . E000 H

Total upper memory available . . . . . . 0 KB
Largest Upper Memory Block available . . 0 KB
Upper memory starting address . . . . . . CF00 H

EMM386 Active.

Memory Type Total Used Free
---------------- -------- -------- --------
Conventional 640K 122K 518K
Upper 31K 20K 11K
Reserved 0K 0K 0K
Extended (XMS)* 457,633K 3,003K 454,630K
---------------- -------- -------- --------
Total memory 458,304K 3,145K 455,159K

Total under 1 MB 671K 142K 529K

Total Expanded (EMS) 32M (33,947,648 bytes)
Free Expanded (EMS)* 32M (33,554,432 bytes)

* EMM386 is using XMS memory to simulate EMS memory as needed.
Free EMS memory may change as free XMS memory changes.

Largest executable program size 518K (530,224 bytes)
Largest free upper memory block 8K (8,368 bytes)
MS-DOS is resident in the high memory area.

I have been using the fre-11 function in program, to send to customers to do a pre check
to determine if there system is configured properly to use EMS.

For this particular Toshiba, the Fre-11 function reports back:

EMS Memory Available = 33,554,432

I have tried several include/exclude ranges to try to obtain a contiguous
64k page frame, and can not prevent the system from freezing after the array is loaded.

Is there any test that will validate what page frames are available for EMM386?

TIA,

Tim Camarda

------------------

[Mel Bishop]

Since you didn't specify where you used Fre -11 at, have you
used it after the "Print DONE" to see how much memory you have
available after the data load?


------------------

[Tim Camarda]

Mel,

I used the Fre-11 in a seperate program to check availiable EMS.

However, maybe I should include it after the array is loaded, after DONE
is printed.

------------------

[Michael Mattias]

For sure you should be testing ERR after the DIM statement.

If that DIM failed who knows what kind of weird stuff could happen.

Sure, without an ON ERROR GOTO (also not a bad idea at least for this section of code), the program *should* fail at that point, but why not be sure?




[This message has been edited by Michael Mattias (edited September 24, 2005).]

[Davide Vecchi]

Is "$ERROR ALL" correct syntax ? I can't remember fur sure nor can check now, but shouldn't it be "$ERROR ALL ON" or something like that ?

When i was DIMing a VIRTUAL array while no EMS was available, IIRC i was getting an error (twohundredsomething) no matter what. Testing ERR should be needed only if something like "ON ERROR RESUME NEXT" was active.

I'm going by memory (which is neither Expanded nor Extended and it often fails ) though.

------------------
Davide Vecchi
[email protected]

[Jerry Mason]

In an $ERROR directive, if ON/OFF are not specified then ON is assumed

------------------

[Davide Vecchi]

I just tested with $ERROR ALL ON (Windows 2000): if i provide no EMS (playing with the PIF settings) the program gives an error on the DIM VIRTUAL. The error code is 202; then it terminates (since there is no ON ERROR GOTO).

------------------
Davide Vecchi
[email protected]

[Frank Cox]

That's interesting -- there is no error 202 defined in the PB reference manual.

------------------
PB/DOS 3.5 on Fedora Linux

[Tim Camarda]

Thanks all for your suggestions.

The $ERROR ALL will work for conditions such as when there is not
sufficient EMS available while filling the array, and will produce an error code.

The problem with the Laptop is an issue with not enough space in the UMB.

However, EMM386,exe gives no error message, but most likely is overlapping while setting it self up in the UMB.
Also, fre-11 reports 32 megs of EMS.

In any case the solution is to set up the page frame manually.

Doing a UMB check, there appears to be only one range of locations available for EMM386.
But, this still causes an issue with EMM386.exe reporting this:
WARNING: Option ROM or RAM detected within page frame.

So, EMM386 is loading its page frames where part of the ROM is setting up.

It is a matter of tweaking and configuring the EMM386 driver, to load its page frames in an area of the UMB with no conflicts.

Thanks again.

Tim



------------------

[Davide Vecchi]

that's interesting -- there is no error 202 defined in the pb reference manual.

i can't check now, however i think that when i got this error the first time i found a regular explaination, i'm not sure if on the docs or not.

a couple of threads that mention this error suggest that it's documented: http://www.powerbasic.com/support/pb...read.php?t=690 http://www.powerbasic.com/support/pb...read.php?t=135

------------------
davide vecchi
[email protected]

[Michael Mattias]

From PB/DOS 3.5 help file, Contents/Error codes/page down a couple

  Error 202: Expansion memory error
 
  Not enough EMS memory was available to perform the operation.

[Frank Cox]

> From PB/DOS 3.5 help file, Contents/Error codes

Sho'nuff, she's there.

Still interesting that it's not in the book (neither the printed manual or the PDF version).

I guess the lesson to take away from this is that if something odd shows up that's not documented in the manual, check the help file for possible enlightenment instead.

------------------
PB/DOS 3.5 on Fedora Linux

[Donald Darden]

EMS and XMS configuration were complicated by the loading of
device drivers that may require their own memory allocations,
possibly even more memory for buffers. Further, some
device drivers required more memory to set up initially,
and released some of the memory once that was done.

Most drivers give you a selection of alternative address ranges
that they can use, but DOS was not really designed to ensure that
there were no conflicts or overlaps. It could take hours to work
your way through the endless array of possible device loading
sequences and range options using the CONFIG.SYS and AUTOEXEC.BAT
files until you had a stable configuration.

One of the big conflict areas that came up late in the DOS
cycle was the emergence of new Video Cards and shared video
memory. Where what memory mapping occurred could be an issue
as well. Unfortunately, this often meant that you could not
assume that client machines were able to run programs that
were designed to rely on EMS and XMS memory, or even to use
a RAM Drive.


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Old Navy Chief, Systems Engineer, Systems Analyst, now semi-retired