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>16 meg memory with OS/2
{{Article
|Author=
|Date=1993-08-01
|OS=OS/2 2.0
|File=N/A
|Source=[https://archive.org/download/gigabyte_gold/gold.zip/gold%2FOS2%2F16MEG.ZIP 16MEG.ZIP]
}}
==>16 meg memory with OS/2==


The >16 meg memory problem has been fixed with  
The >16 meg memory problem has been fixed with  
a couple of files that can be found on CompuServe.
a couple of files that can be found on CompuServe.


[http://cd.textfiles.com/megawin2/OS2/MISC/GT16MB.ZIP GT16MB.ZIP] can be found in the IBMOS2 support forum, in the IBM Files library (library 17).  This is a replacement OS2LDR file for pre-Service Pak machines.
* [http://cd.textfiles.com/megawin2/OS2/MISC/GT16MB.ZIP GT16MB.ZIP] can be found in the IBMOS2 support forum, in the IBM Files library (library 17).  This is a replacement OS2LDR file for pre-Service Pak machines.
* [https://ftp.hanmesoft.com/OS2/os2bbs.com/fixes20/sp16mb.zip SP16MB.ZIP] can be found in the same library, and is to be used for post-Service Pak machines.  It is not to be installed on OS/2 GA version or OS/2 2.1.


SP16MB.ZIP can be found in the same library, and is to
The XR06055 SVCPK resolves the problem for ISA machines, there is a special SP16MB fix available after the shipment of XR06055 that contains the same fix for EISA bus machines.
be used for post-Service Pak machines.  It is not to be
installed on OS/2 GA version or OS/2 2.1.


The XR06055 SVCPK resolves the problem for ISA machines,
All related >16 meg memory problems should have been fixed for OS/2 2.1.
there is a special SP16MB fix available after the shipment of
XR06055 that contains the same fix for EISA bus machines.


All related >16 meg memory problems should have been
I have come across a file that will help answer your questions about using >16 megs of memory with OS/2 2.0. I will include it below:
fixed for OS/2 2.1.


I have come across a file that will help answer your questions
==Greater than 16 MegaBytes of RAM with OS/2 2.0==           
about using >16 megs of memory with OS/2 2.0.  I will include
Keywords : greater 16Mb Mb RAM meg                             
it below:


** Greater than 16 MegaBytes of RAM with OS/2 2.0 **           
The purpose of this infoapar is to shed some light on the problem of supporting / using greater than 16Mb of RAM under OS2 2.0. First, only certain processors support more than 16Mb of RAM. The following processors support >16mb: 386DX 486SX & 486DX  
Keywords : greater 16Mb Mb RAM meg                             
These do *not* support >16Mb : 386SX 386SLC & 486SLC2.
    The purpose of this infoapar is to shed some light on the  
          
problem of supporting / using greater than 16Mb of RAM under OS2  
Note: The AOX processor upgrade cards *do* support more than 16 Mb in 24-bit address bus machines, as long as there is less than 16Mb in the host machine and the extra memory is local to the AOX processor, and subject to there being sufficient AOX memory  below the 16Mb line to load the kernel. AOX processors must run  in unmapped mode for 2.0 (they ran mapped in 1.3).               
2.0. First, only certain processors support more than 16Mb of  
 
RAM. The following processors support >16mb: 386DX 486SX & 486DX  
If the processor supports more than 16 meg of RAM, the first issue for OS/2 is finding that RAM. OS/2 uses BIOS INT calls in real mode to identify available RAM, and is therefore subject to any BIOS bugs or restrictions.                                   
These do *not* support >16Mb : 386SX 386SLC & 486SLC2 .           
 
Note: The AOX processor upgrade cards *do* support more than 16
Some machines have required a BIOS upgrade to resolve problems - the first test is to verify the POST memory count, the second is to use debug under DOS or the debug OS2LDR output to verify the return from the INT 15H func 88H call. If the BIOS is giving an invalid memory report, this might be a configuration problem (system setup or reference diskette to fix) or a BIOS bug (contact supplier for fix to BIOS).
Mb in 24-bit address bus machines, as long as there is less than  
                         
16Mb in the host machine and the extra memory is local to the  
AOX processor, and subject to there being sufficient AOX memory   
below the 16Mb line to load the kernel. AOX processors must run   
in unmapped mode for 2.0 (they ran mapped in 1.3).               
    If the processor supports more than 16 meg of RAM, the first  
issue for OS/2 is finding that RAM. OS/2 uses BIOS INT calls in
real mode to identify available RAM, and is therefore subject to  
any BIOS bugs or restrictions.                                   
    Some machines have required a BIOS upgrade to resolve      
problems - the first test is to verify the POST memory count,  
second is to use debug under DOS or the debug OS2LDR output to  
verify the return from the INT 15H func 88H call. If the BIOS is  
giving an invalid memory report, this might be a configuration  
problem (system setup or reference diskette to fix) or a BIOS  
bug (contact supplier for fix to BIOS).                        
BIOS restrictions:                                               
BIOS restrictions:                                               
- ISA machines will only support a maximum of 64 meg of RAM due  
* ISA machines will only support a maximum of 64 meg of RAM due to INT 15H func 88H limits.                                       
to INT 15H func 88H limits.                                       
* The same limit applies to IBM MicroChannel machines, including those that support INT 15H func C7H.                             
- The same limit applies to IBM MicroChannel machines, includin
* For ISA and MicroChannel machines, RAM must be contiguous to be found, with the exception of machines supporting INT 15H func C7H (mod 90/95). I.e.: discontinuous memory is only supported for EISA machines, or for machines supporting INT 15H func C7H.       
those that support INT 15H func C7H.                             
* For EISA machines, support for 512 meg of RAM is enabled.     
- For ISA and MicroChannel machines, RAM must be contiguous to
 
be found, with the exception of machines supporting INT 15H func  
*WARNING*  Bus memory is slower than planar memory due to additional wait states. Dependent on machine loading, adding bus memory may result in apps being loaded into bus memory instead of planar memory, and thus making the system run slower. If a machine already has adequate RAM, adding RAM can therefore slow the system.
C7H (mod 90/95). ie: discontiguous memory is only supported for
                                                 
EISA machines, or for machines supporting INT 15H func C7H.       
*WARNING*  Processor caches may be restricted to the low 16meg, or may need to be reconfigured (system setup) to cache memory   
- For EISA machines, support for 512 meg of RAM is enabled.     
above 16 meg. If adding memory means applications run in non-cached memory instead of cached memory, the system may run slower.                                                         
*WARNING*  Bus memory is slower than planar memory due to addit-
 
ional wait states. Dependent on machine loading, adding bus    
Assuming OS/2 can find the memory, there are 2 options on how memory may be used: 1) As in memory swap file cache, or 2) As regular paged memory for application use. In either case, when adding memory, the swap file should shrink by approximately the amount of memory added if all is well. Option 1 may require applying a fix which was included in the Service Pak XR06055.
memory may result in apps being loaded into bus memory instead  
 
of planar memory, and thus making the system run slower. If a
Option 2 applies if the disk device driver can access memory above the 16Mb line. This is disk device driver implementation dependent. As a guideline, IBM's drivers:
machine already has adequate RAM, adding RAM can therefore slow
:1) can only access above the 16 meg line if the disk controller has access to 32bit DMA - note that putting a 32bit SCSI controller in a 32bit slot in a Model 80 (a 24bit DMA machine) gives the disk device driver this capability.  
the system.                                                  
:2) PIO (Port I/O) drivers do not use DMA, therefore are not restricted.
*WARNING*  Processor caches may be restricted to the low 16meg,
                                    
or may need to be reconfigured (system setup) to cache memory   
*WARNING*  A 32bit disk controller card *must* reside in a 32bit slot. There will be no hardware errors or config errors if this is not the case. The system will simply fail in strange ways.     
above 16 meg. If adding memory means applications run in      
 
non-cached memory instead of cached memory, the system may run  
slower.                                                         
    Assuming OS/2 can find the memory, there are 2 options on
how memory may be used: 1) As in memory swap file cache, or 2)
As regular paged memory for application use. In either case,  
when adding memory, the swap file should shrink by approximately
the amount of memory added if all is well. Option 1 may require  
applying a fix which was included in the Service Pak XR06055.  
Option 2 applies if the disk device driver can access memory  
above the 16Mb line. This is disk device driver implementation
dependent. As a guideline, IBM's drivers: 1) can only access  
above the 16 meg line if the disk controller has access to 32bit
DMA - note that putting a 32bit SCSI controller in a 32bit slot  
in a Model 80 (a 24bit DMA machine) gives the disk device driver  
this capability. 2) PIO (Port I/O) drivers do not use DMA,      
therefore are not restricted.                                     
*WARNING*  A 32bit disk controller card *must* reside in a 32bit  
slot. There will be no hardware errors or config errors if this
is not the case. The system will simply fail in strange ways.     
Service Pak comments:                                             
Service Pak comments:                                             
                                                                  
                                                                  
*WARNING* The Service Pak will regress all >16Mb RAM * EISA *  
*WARNING* The Service Pak will regress all >16Mb RAM * EISA * machines to be limited to 16 meg. This will be fixed in a future service pak.                                                     
machines to be limited to 16 meg. This will be fixed in a future  
 
service pak.                                                     
*WARNING* IBM Expanded Memory Option cards will not work above the 16 meg line *unless* a microcode enhancement is applied to the card. This microcode enhancement is in Beta test and is not currently generally available.                                   
*WARNING* IBM Expanded Memory Option cards will not work above
 
the 16 meg line *unless* a microcode enhancement is applied to  
the card. This microcode enhancement is in Beta test and is not
currently generally available.                                   
VDISK information regarding >16Mb :                               
VDISK information regarding >16Mb :                               
    VDISK code has been changed in the Service Pak to allow the
: VDISK code has been changed in the Service Pak to allow the following:
following: 1) loads VDISKs above the 16 meg line if possible, 2)  
::1) loads VDISKs above the 16 meg line if possible,  
allows VDISK bigger than 4 meg. This should help performance, as  
::2) allows VDISK bigger than 4 meg. This should help performance, as well as lifting some restrictions some people had.
well as lifting some restrictions some people had.
 
[[Category:How To]]

Latest revision as of 12:00, 24 March 2025

Article Info
Author
Date 1993-08-01
OS Version OS/2 2.0
Companion File N/A
Source 16MEG.ZIP

>16 meg memory with OS/2

The >16 meg memory problem has been fixed with a couple of files that can be found on CompuServe.

  • GT16MB.ZIP can be found in the IBMOS2 support forum, in the IBM Files library (library 17). This is a replacement OS2LDR file for pre-Service Pak machines.
  • SP16MB.ZIP can be found in the same library, and is to be used for post-Service Pak machines. It is not to be installed on OS/2 GA version or OS/2 2.1.

The XR06055 SVCPK resolves the problem for ISA machines, there is a special SP16MB fix available after the shipment of XR06055 that contains the same fix for EISA bus machines.

All related >16 meg memory problems should have been fixed for OS/2 2.1.

I have come across a file that will help answer your questions about using >16 megs of memory with OS/2 2.0. I will include it below:

Greater than 16 MegaBytes of RAM with OS/2 2.0

Keywords : greater 16Mb Mb RAM meg

The purpose of this infoapar is to shed some light on the problem of supporting / using greater than 16Mb of RAM under OS2 2.0. First, only certain processors support more than 16Mb of RAM. The following processors support >16mb: 386DX 486SX & 486DX These do *not* support >16Mb : 386SX 386SLC & 486SLC2.

Note: The AOX processor upgrade cards *do* support more than 16 Mb in 24-bit address bus machines, as long as there is less than 16Mb in the host machine and the extra memory is local to the AOX processor, and subject to there being sufficient AOX memory below the 16Mb line to load the kernel. AOX processors must run in unmapped mode for 2.0 (they ran mapped in 1.3).

If the processor supports more than 16 meg of RAM, the first issue for OS/2 is finding that RAM. OS/2 uses BIOS INT calls in real mode to identify available RAM, and is therefore subject to any BIOS bugs or restrictions.

Some machines have required a BIOS upgrade to resolve problems - the first test is to verify the POST memory count, the second is to use debug under DOS or the debug OS2LDR output to verify the return from the INT 15H func 88H call. If the BIOS is giving an invalid memory report, this might be a configuration problem (system setup or reference diskette to fix) or a BIOS bug (contact supplier for fix to BIOS).

BIOS restrictions:

  • ISA machines will only support a maximum of 64 meg of RAM due to INT 15H func 88H limits.
  • The same limit applies to IBM MicroChannel machines, including those that support INT 15H func C7H.
  • For ISA and MicroChannel machines, RAM must be contiguous to be found, with the exception of machines supporting INT 15H func C7H (mod 90/95). I.e.: discontinuous memory is only supported for EISA machines, or for machines supporting INT 15H func C7H.
  • For EISA machines, support for 512 meg of RAM is enabled.
  • WARNING* Bus memory is slower than planar memory due to additional wait states. Dependent on machine loading, adding bus memory may result in apps being loaded into bus memory instead of planar memory, and thus making the system run slower. If a machine already has adequate RAM, adding RAM can therefore slow the system.
  • WARNING* Processor caches may be restricted to the low 16meg, or may need to be reconfigured (system setup) to cache memory

above 16 meg. If adding memory means applications run in non-cached memory instead of cached memory, the system may run slower.

Assuming OS/2 can find the memory, there are 2 options on how memory may be used: 1) As in memory swap file cache, or 2) As regular paged memory for application use. In either case, when adding memory, the swap file should shrink by approximately the amount of memory added if all is well. Option 1 may require applying a fix which was included in the Service Pak XR06055.

Option 2 applies if the disk device driver can access memory above the 16Mb line. This is disk device driver implementation dependent. As a guideline, IBM's drivers:

1) can only access above the 16 meg line if the disk controller has access to 32bit DMA - note that putting a 32bit SCSI controller in a 32bit slot in a Model 80 (a 24bit DMA machine) gives the disk device driver this capability.
2) PIO (Port I/O) drivers do not use DMA, therefore are not restricted.
  • WARNING* A 32bit disk controller card *must* reside in a 32bit slot. There will be no hardware errors or config errors if this is not the case. The system will simply fail in strange ways.

Service Pak comments:

  • WARNING* The Service Pak will regress all >16Mb RAM * EISA * machines to be limited to 16 meg. This will be fixed in a future service pak.
  • WARNING* IBM Expanded Memory Option cards will not work above the 16 meg line *unless* a microcode enhancement is applied to the card. This microcode enhancement is in Beta test and is not currently generally available.

VDISK information regarding >16Mb :

VDISK code has been changed in the Service Pak to allow the following:
1) loads VDISKs above the 16 meg line if possible,
2) allows VDISK bigger than 4 meg. This should help performance, as well as lifting some restrictions some people had.