Kbase 12208: Protected Mode: VCPI vs. DPMI Why we use Expanded Memory;dos
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
10/05/1998 |
|
Protected Mode: VCPI vs. DPMI Why we use Expanded Memory;dos
This notebook entry addresses two of the questions most often asked
by PROGRESS customers:
1. Why does Protected Mode use expanded memory when the installation
manual states that PROGRESS needs extended memory?
2. How does my memory manager need to be configured?
PROGRESS is NOT concerned if the memory is extended or expanded.
PROGRESS requires VCPI (Virtual Control Program Interface) compliant
memory, opposed to DPMI (Dos Protected Mode Interface) compliant
memory. VCPI is a requirement of the DOS Extender used by Protected
Mode. PROGRESS uses Ergo`s OS286 DOS extender.
The following scenarios describe how to setup a DOS machine's memory
to have VCPI compliant memory for different memory managers.
No Memory Manager Used (or only HIMEM.SYS in config.sys):
PROGRESS uses Ergo's own internal memory manager. You don't
need to set up anything.
Microsoft's EMM386 v4.4 and older (in conjunction with HIMEM.SYS):
By default, EMM386 emulates DPMI compliant memory. For EMM386
to emulate VCPI memory, you must use the {size} RAM parameter.
For example:
device=c:\dos\EMM386 2048 RAM
The 2048 RAM parameter blocks 2MB of RAM as VCPI compliant
memory. The 2048 is in 1000 byte (1k) size, therefore, you get
2MB. When a DOS MEM is done, this 2MB of RAM appears expanded
because VCPI memory is a page framed interface. In addition, the
NOEMS and the FRAME=NONE parameters for EMM386 do not work. They
shut off the page frame in the memory above 1MB required by
Protected Mode and VCPI.
Other Memory Managers(QuarterDeck's QEMM, 386max, EMM386 v4.45 (dos6))
These memory managers are 'smart' enough to know what interface
an application needs (VCPI or DPMI), so no parameters are required
for Protected Mode to work. Once again, if the NOEMS or the
FRAME=NONE parameters are used, the page frame is turned off and
Protected Mode does not work. You can't use these or any other
parameters that turn off the page frame with Protected Mode
PROGRESS.
The Progress Version 7 DOS product will be DPMI compliant.
Progress Software Technical Support Note # 12208