🚀 go-pugleaf

act@softserver.canberra.edu.au (Andrew Turner) writes:

>4. You will not be able to use your 384 Kb on the 286 as this requires
>EMM386.EXE to be loaded.

>5. To quote Microsoft:

>	"UMA support for 80286 class machines is not supplied in MS-DOS 5.0.
>	The choice to use EMM386.EXE as the engine for using Upper Memory
>	Blocks has been motivated by two major factors.

>	1. High Memory is available on both 80386 and 80286 machines. To
>	prevent having two drivers, one for each machine.

>	2. Development research indicated that UMB savings on 80286 class
>	machines did not offset the memory costs of the UMB driver nor
>	development time.

>	MS-DOS 5.0 OEMs have shown interest in developing UMA capabilities
>	into their releases. OEMs do have options that were not addressed
>	by Microsft's project, options such as Hardware and Firmware
>	solutions."

Does this mean that all those 286 systems of recent vintage with the Chips &
Technologies memory control chipset are out of luck?  Why would an XMS driver
for the upper memory area on a 286 C&T system have more "memory costs" than
EMM386 on a 386 system?  In any case, I would at least be able to use ~64K 
of the above memtioned 384K (assuming it was extended and not dedicated shadow 
ram) as HMA, is that correct?  Can anyone with MSDOS 5.0 and a 286 class 
machine elaborate on the above quotes from Microsoft?

--
Jimmy Liberato   liberato@dri.com
                 ...uunet!drivax!liberato