Re: Question about UMBs

X-Comment-To: Paul Case

Hi!

31-Окт-2002 14:39 [email protected] (Paul Case) wrote to [email protected]:

>>>since, so... I'm wondering how a UMB provider informs DOS that there's
>>>now memory about the video buffer at A0000-BFFFF?
>>XMS function 0x10 (see RBIL int2f/4310)

     Also 11h and 12h functions.

PC> Ehm... I'm not looking to provide a UMB manager, but just let DOS manage
PC> them once they're there.

     If you install your own XMS manager (which implements UMB support) into
XMS managers chain, then it may inform DOS that there UMB is available.

PC> I couldn't find the source code to UMBPCI
PC> anywhere, and since the UMB service it provides looks very attractive to me,

     Whay you not clear there? You only should implement above mentioned
three functions to support UMB. Of course, you also should implement code,
which will insert your code into existing XMS chain (or create new XMS chain
and implement installation check).

PC> available to test with). So, I have (in pure DOS mode on this machine)
PC> an extra 144KB of memory, but I don't know how to inform DOS about it....

     You can't, DOS itself gather this info from XMS services if it
instructed by DOS=UMB statement in config.sys.

>>>is it possible to create a .sys file, loadable by the
>>>DEVICE command in config.sys, that won't take any memory after
>>>initialization? Meaning, it loads, does its job, and is completely out
>>>of memory afterwards.

     Yes. For example, I have driver, which runs, changes video BIOS fonts
in shadow memory (localization), then exit without remaining resident code.