[comp.os.os2.misc] DOS Extended memory Support Under OS/2 R2.0

klimas@iccgcc.decnet.ab.com (10/06/90)

Can someone clarify what kind of extended and expanded memory support
OS/2 2.0 will provide for the DOS box.  The latest issue of BYTE's
supplement has an article on OS/2 2.0 that implies that OS/2 2.0 will
support DOS programs that use extended as well as expanded memory running
from the DOS box.  Is this accurate and what are the gotchas?

martin@cat.uucp (Thomas Martin) (10/07/90)

klimas@iccgcc.decnet.ab.com (klimas@iccgcc.decnet.ab.com) schrieb am  5.10.:
> Can someone clarify what kind of extended and expanded memory support
> OS/2 2.0 will provide for the DOS box.  The latest issue of BYTE's
> supplement has an article on OS/2 2.0 that implies that OS/2 2.0 will
> support DOS programs that use extended as well as expanded memory running
> from the DOS box.  Is this accurate and what are the gotchas?

According to an IBM publication (spring 90) describing the features of OS/2
2.0, the DOS compatibility box will have the following characteristics:

- 4.0 compatability
- Due to the usage of the V86 mode of the 80386/80486 it will be possible to
terminate a hung DOS session from the shell.
- The usage of the V86 mode will enable up to 16 concurrent DOS sessions.
Each operating in its own linear 1MB address space.
- DOS applications will run full-screen, windowed or iconized in the
background.
- OS/2 2.0 will leave more than 600K to DOS applications.
- It will support both, EMS and Extended Memory.
- DOS asynchronous communications applications can support communication
speeds of up to 9600 baud.
- DOS sessions are now capable of multitasking.
- EMS capability allows DOS applications to allocate and access up to 32 MB
of expanded mamory in up to 255 EMS objects.
- Due to the V86 mode it will be possible to use vitual memory for DOS
sessions virtually making the usable memory unlimited.

Due to the early stage this article was published, the author pointed out
that some features may be changed or abandoned but I personally think we
will all find them to be true in the final product because all of these
great DOS features are due to the usage of the V86 mode and therefor part of
the underlying hardware.

Another advantage of the V86 mode will be that now the processor will operate
solely in its protected mode (the V86 mode is protected) eliminating
the time-consuming switch from real to protected mode and back necessary for
operating DOS in the 1.x versions.

I hope that helps a little bit.

Regards,

Thomas

---
  Thomas Martin (martin@cat.de)                     
  C.A.T. Kommunikations-System, Frankfurt 

jmerrill@jarthur.Claremont.EDU (Jason Merrill) (10/09/90)

In article <1990Oct6.181227.11104@cat.uucp> martin@cat.uucp (Thomas Martin) writes:
>According to an IBM publication (spring 90) describing the features of OS/2
>2.0, the DOS compatibility box will have the following characteristics:
>
[serveral features deleted]
>- DOS asynchronous communications applications can support communication
>speeds of up to 9600 baud.

This is pretty poor; I'm currently running MS-Kermit 3.02 under DOS/Windows
3 at 19200 baud, and I've had no problem with 38400 (except in downloading
files, but...)

Of course, one of the main reasons I use a DOS comm program is that DOS
boxes under Win3 are pre-emtively multitasked, while Windows programs are
not, so Windows comm programs are more prone to losing characters when
another program is active.  With OS/2's pre-emptive multitasking this should
be fixed, but still it's likely to be a while before there's an OS/2
terminal emulator as fully-featured as MS-Kermit.

--
Jason Merrill				jmerrill@jarthur.claremont.edu