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BC 4030
Chapter 4 - Memory Configurations
Memory Configurations
DOS Versions and Memory Management
Video Memory Options
Memory Configuration Hints
The BC 4030 supports from 4 to 64MB of system memory. The minimum configuration supplied by Cubix is 4MB.
Memory below 1MB is divided into two defined sections, Conventional DOS addressable or Transient Program Area (TPA) and Upper Memory.
DOS compatible executable programs load and execute in the TPA. Upper Memory is memory reserved for system BIOS and devices that require an addressable memory window. Video adapters, mass storage device interfaces, network interface cards, and other add-in cards reside in the Upper Memory area. An Expanded Memory page frame as defined by the Lotus-Intel-Microsoft, or LIM, specification can also occupy part of the Upper Memory area.
Memory above 1MB can be utilized by DOS as Extended Memory (XMS), Expanded Memory (EMS), or a combination of both. Extended Memory is compatible with XMS and VCPI standards. Expanded Memory is compatible with LIM 3.2 and 4.0 specifications. To configure memory above 1MB as EMS or XMS memory, an Extended or Expanded Memory Driver must be installed. Cubix does not supply a memory driver with the BC 4030. Extended and Expanded Memory drivers are available in Microsoft DOS 5.x, Novell DR DOS 6.x, and from several third-party vendors.
Use memory below 1MB according to the memory map illustrated in Figure 4-1.
Memory between 640KB and 1MB not required by hardware memory windows or BIOS can be made available to DOS. By configuring these areas as EMS page frames or Upper Memory Blocks, they can be used for loading and executing application software such as TSRs (Terminate and Stay Resident programs) and network drivers.
Microsoft DOS 3.x and DOS 4.x
MS DOS versions 3.x and 4.x require third party memory managers to utilize memory between 640KB and 1MB.
Microsoft DOS 5.x
MS DOS 5 includes memory management for 80386 class processors to allow memory between 640KB and 1MB to be remapped as Upper Memory Blocks (UMBs). The DOS LOADHIGH command can be used to relocate programs such as NetWare's IPX and NETX into available UMBs.
Since the DOS 5.x memory manager runs in Extended Memory above 1MB, the processor must have enough available memory defined as Extended Memory to load the memory manager. The remaining memory can be allocated as Extended or Expanded Memory.
Novell DR DOS 6.x
DR DOS 6.x includes memory management for 80386 class processors and other processors with LIM 4.0 compatible memory systems allowing memory between 640KB and 1MB to be remapped as UMBs. The DOS HIGHLOAD command can be used to relocate programs such as NetWare's IPX and NETX into available UMBs.
The BC 4030 has a VGA controller built into the board. This controller cannot be disabled; the video BIOS on the card will always occupy the upper memory window at C0000-C7FFF. If the application being executed on the BC 4030 card does not require all of the graphics capabilities of the VGA controller, other Upper Memory areas normally devoted to video may be used as an extension of the DOS TPA.
If graphics applications will not be run on the BC 4030 board, the VGA Graphics Buffer (A0000-AFFFF) can be mapped by the memory manager drivers as an extension of the 640KB of conventional (TPA) DOS memory area. This will increase the TPA to 704KB. If the BC 4030 is to be used for applications that require only CGA Graphics support, the VGA Graphics Buffer (A0000-AFFFF) and the MDA (Monochrome Display Adapter) Text Buffer (B0000-B7FFF) areas of memory may be mapped by the memory manager as an extension of DOS, increasing TPA to 736KB.
VGA memory applications do not require use of the MDA text buffer (B0000-B7FFF). The memory manager can map and use this area as Upper Memory Blocks (UMBs).
F Any application that attempts to use a video buffer that has been remapped by a memory manager will cause the processor to fail. Cubix does not recommend remapping video memory with MS DOS 5.0 or DR DOS 6.0 unless care is taken to restrict the ability of the user to run applications that can access these areas as video memory.
1. The memory management drivers provided with MS DOS 5.0 or DR DOS 6.0 require a minimum of 2MB of RAM.
2. Remember to EXCLUDE memory areas which are mapped as memory windows for LAN adapters.
3. In order to form the largest continuous blocks of Upper Memory, set the LAN adapter to use the memory window starting at the end of the VGA BIOS area, at memory location C8000.
For Ethernet set the adapter to use the 16KB of RAM from addresses C8000 to CBFFF.
For IBM Token Ring Adapters use the IBM default settings:
* set the ROM address to 16KB from RAM addresses CC000-CFFFF
* set the 8KB shared RAM address to C8000-C9FFF with an IPX parameter in the AUTOEXEC.BAT file:
IPX o,mem=C800
4. Set the EMS Page Frame address to E0000 to leave the largest possible free block between the LAN adapter memory window and the Page Frame.
This document, and all Web contents, Copyright © 1997
by Cubix Corp., Carson City, NV, USA.
