> Calling the BIOS on such a "new BIOS" mainboard WILL cause crashes
Does this mean that FreeDOS will not boot at all on these systems or do you
not mean BIOS interrupts?
73 Matt Rienzo W9ERA
B.S.E.E | B.S. Music
On Jan 13, 2016 1:25 AM, "Eric Auer" <e.a...@jpberlin.de> wrote:
>
> Jack writes:
>
>
>
> Eric,
>
> Re: your FD-User post about "new BIOS" UltraDMA errors, the post has
> "just a few" ERRORS, which you need to correct:
>
> First, the title of your post, "BIOS with broken UDMA needs DOS disk
> driver loaded before JEMMEX", should be changed. Instead of saying
> "UDMA" that you and I understand, use the full word "UltraDMA" which
> many more people would more-immediately understand. Also, one does
> not need to load a DOS disk driver, which might be seen as "any" DOS
> driver.One must ABSOLUTELY load a DOS *ULTRADMA* disk driver, as
> this "new BIOS" problem applies only to UltraDMA done in "v86" mode!
>
> > Some mainboards have a BIOS with faulty UDMA in V86 mode support!
>
> Better to say "Some *new* mainboards have a BIOS with faulty support
> for UltraDMA in V86 mode". Better English; and again, you should
> replace "UDMA" with the full word "UltraDMA".
>
> > ... The presence of EMS memory hardware is simulated by moving
> > DOS into a V86 task.
>
> Absolutely NOT TRUE! "V86" mode was created by Intel to provide a
> way of (a) running 16-bit programs on 32-bit systems, (B) providing
> protection for the system from such programs. EMS hardware is NOT
> "simulated" but is REQUIRED to access extended memory, which is the
> "E" in EMS!
>
> > When the BIOS fails to support UDMA (memory block copy and block
> > copy between memory and I/O devices) properly in V86, attempts to
> > transfer disk data can fail or end up at the wrong places in RAM.
>
> NOT what Martin Rehak saw! He got "Cold" DOS disk ERRORS, when his
> system tried to do UltraDMA output using his new mainboard. He did
> NOT indicate what happened to his data, during such I-O transfers --
> Martin got only disk I-O errors from his V6.22 SYSTEM!
>
> > DOS disk drivers could potentially test if your BIOS is buggy, but
> > it will not always be possible to do that without causing a crash.
> > In the BEST case, the driver could conclude that no UDMA will work.
>
> Given Martin's new mainboard, it will NEVER be possible to do such a
> test, I guarantee you! Also, if we limit "DOS disk drivers" to the
> ones I wrote, assuming "no UltraDMA will work" says the drivers MUST
> "call the BIOS" to do such I-O. My drivers were meant for UltraDMA
> and have no "PIO mode" code for disks (XDVD2 must have it for CD/DVD
> "audio" and other drive commands). Calling the BIOS on such a "new
> BIOS" mainboard WILL cause crashes, as the BIOS itself is a PROBLEM!
>
> > In the WORST case (!), the BIOS itself defaults to UDMA disk access
> > and crashes as soon as you enter V86 mode. In that case, you will
> > be FORCED to load a driver like XHDD or UIDE before loading JEMMEX
> > to protect your BIOS from its own stupidity ...
>
> Not the worst-case, but the EXPECTED case, as modern BIOS programs
> ALL use UltraDMA to improve speed! Also, unless you desire nasty
> words from my "good friends" Rugxulo and Hall, I would not mention
> XHDD, since it shall remain closed-source and thus unavailable for
> use within FreeDOS, also unavailable for archiving on SourceForge.
>
> > To avoid crashes, it is important to LOAD DISK DRIVERS BEFORE EMM
> > (if your BIOS is affected by such bugs). For example, load XHDD in
> > your boot process before you load JEMMEX. If you disk driver is
> > using XMS (for example as cache) you can of course not use JEMMEX
> > as your XMS driver, but have to load a separate XMS driver before
> > the cache, as JEMMEX has to be loaded after the disk driver...
>
> Likely a very "confusing" paragraph, for the average user! Again
> I would suggest NOT mentioning XHDD, as it shall never be any part
> of FreeDOS. Do try to write "simplified" English so more of your
> users will understand what is going on. I target "4th graders",
> which some view as insulting. But, I know doing so is NECESSARY!
>
> > Some drivers can use HMA space provided by XMS drivers (as HIMEM)
> if no UMB space (provided by EMM386 and similar) is available ...
>
> Never heard of any other DOS drivers loading in HMA, except my own.
>
> > Jack recommends to lo
