Uploaded to ftp://ftp.devoresoftware.com/downloads/emm386 are the files
emmx205.zip, EMM386/HIMEM mostly executable package, and emms205.zip,
EMM386/HIMEM mostly source package.
This version of EMM386 has a number of compatibility changes to enhance
operability with a variety of DOS applications and environments without the
need for advanced option tweaking. As a result of the seven changes to
EMM386 and two changes to HIMEM, this is a recommended released.
Briefly, besides various fixes and compatibility modifications, the VDS
option now defaults to on, with a new NOVDS option to turn it off (NOVDS
possibly required for some SCSI disk drivers); the XMS memory manager
supports growing memory blocks on resize for the Graphics Vision text
editor; and a limited MEMCHECK default of 3-4G is present for MMIO-based
devices such as USBASPI.SYS, with the ability to turn it all off by use of
the new NOCHECK option.
Particulars ponderously proceed post-paragraph:
The HMAMIN setting of HIMEM never up-converted its K setting to actual
bytes as required internally, plus it allowed 64K instead of a maximum of
63K. Bad HMAMIN, bad boy. Fixed.
The NOVCPI option was blocking allocation of UMBs. This was overly
aggressive, even for a severe option like NOVCPI, and it was chastised back
to proper behavior. Regardless of that whoopsie, friends don't let friends
use NOVCPI, as it is almost never a good idea. Unless you know exactly why
you are using NOVCPI, don't.
There was an error when parsing EMS, such that an EMS page frame was marked
present even if there was insufficient upper memory (i.e. no 64K contiguous
block) to place it properly. The problem would not be present if you
specified NOEMS and even without NOEMS it would not cause misbehavior
unless you used an application which depended on EMS and a page
frame. Admittedly, it was an error with a nasty bite, but one had to
wander far into the hinterlands of nontypical environments to get
bitten. Such is how developers rationalize away crippling guilt. And
minor bugs.
The EMM386 driver saves the full 32-bit part of all general registers it
uses, as well as segment registers. This may or may not clear up problems
with 386-optimized kernels. I can't test. It consumes an additional 22
bytes of stack, which I'm thinking probably shouldn't be a problem. Of
course, I used to think an incompetent buffoon probably wouldn't make a
second term as President, and now look what the USA is stuck with, so
counting on me to tell you whether a particular kernel version is safe
seems chancy.
HIMEM's XMS API supports growing a block on resize; previously only
shrinking was supported. Sufficient contiguous memory must be available to
simultaneously hold the old block and the new block or else it will
fail. This feature was added because the Graphics Vision text editor did
not gracefully handle a failed XMS growing resize, although resizing is
never guaranteed. I don't know whether it's a bound-in extender fault or
an application fault, but something is acting goofy in there and we're
stuck writing the work-around for it. Not that I feel crabby about it.
EMM386's VDS option had a bug in the scatter/gather function and made
various setups, such as Bernd's VMWare and Mark Bailey's laptop, cry in
grief and frustration at the unfairness of it all. The evil error was
corrected to help better balance Universal Justice towards the Good Guys.
While on the topics of VDS, the VDS option is now on by default. Too many
environments require this to leave it as optional, plus a default on
condition matches Microsoft EMM386. There exist SCSI setups which will
REQUIRE you to turn off VDS support via the new NOVDS
option. Unfortunately for those SCSI-ites, the people who need VDS
outnumber the people who need to not have VDS, so they lost out. Or maybe
the people who need VDS just yell louder. Ahh well, same difference to
me. I like quiet.
EMM386 internally defaults its MAX setting to 256M, so that unless you
explicitly specify a MAX= setting more than 256M, available VCPI will not
exceed this amount. This change was made solely to accommodate the DOS/32A
extender complaining when large amounts of free VCPI memory are
available. Applications which used the extender would fail with a fatal
error in such cases, including MPXPLAY -- an otherwise extremely impressive
DOS program that deserves major kudos. It appears that DOS/32A is dumb as
a leaf of lettuce about the whole lots of VCPI available thing, which kind
of sours me on those rabid endorsements of it.
The final change is to ensure better compatibility with device drivers that
use MMIO (memory-mapped I/O) to high addresses outside of normal RAM, such
as USBASPI.SYS. Previously, the MEMCHECK option was required. EMM386 now
defaults to operating as if MEMCHECK was present IF the source or
destination address range starts (not ends) within the 3G-4G address
space. Should you require MEMCHECK type operation below 3G for a doofus
program or whatever, MEMCHECK is still available to cover all 0-4G. If you
want it to act like it used to (that is, without MEMCHECK capability), use
the new NOCHECK option. That all sounds clear as mud so let me
recap: default -> 3G-4G access allowed, MEMCHECK -> 0-4G allowed, NOCHECK
-> zero, zip, nada, can't access memory outside of RAM space without
lockups, failure, or spontaneous flooding.
Lastly, to follow-up on the announcement of a $0.10 donation to the
International Federation of Red Cross and Red Crescent Societies
(www.ifrc.org) for each unique IP address downloading either the source or
binary package of EMM386 2.04 from my ftp site for the month of July 2005,
the results are in. 570 unique IP addresses accessed the files during that
time, with no evidence of large-scale download inflation counts, based on
typical downloading patterns. Yea, people. I rounded the amount up to
$60.00 and made the contribution on August 9, specified for where it was
most needed with the title 'FreeDOS'. Confirmation e-mail available on
request.
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