Disruptor wrote on 2025-09-15, 11:25:
However, each newer DOS version consumes more conventional RAM and makes it more and more difficult to run programs and games!
Please consider to stop at DOS 5.0 on an XT or AT.
It is a good DOS!
Perhaps, though I had a different experience.
Some DOSes such as PTS DOS or Paragon DOS (Russ. DOSes written in ASM) or Novell DOS 7 have become smaller in RAM than MS-DOS 5/6.
In terms of compatibility, I remember, SETVER on MS-DOS actually helped to get older applications running.
The internal EXE loader might have been improved, too, since DOS 3.30!
Edit: Here are actual numbers, without any interpretation.
Conventional Memory consumption of various DOSes
Please note that DOS 5 onwards support UMB and HMA to upload parts of DOS.
This feature wasn't used in the comparison, though, because no boot up files were used.
On an XT, if you have an UMB card, 64KB of hardware-EMS or original Hercules card then big parts of DOS could be moved out.
On an AT with Extended Memory, about 64 KB are available to hold parts of DOS.
To my understanding, there are essentially three groups that differ in memory consumption in a meaningful way. DOS 2.11, DOS 3.x and 5/6.
Now MS-DOS 2.11 is the last DOS from early 80s, which many XT owners had used.
It was very limited, too, though. FAT12 only, 360 KB floppy format at best, limited DOS devices (such as $clock) no international support yet.
It also had ansi.sys and some Unix compatibility integrated, if memory serves.
It's i/o routines were very slow, also.
DOS 3.3 then had FAT16, but not FAT16B yet. Compaq DOS 3.31 got it.
PC-DOS 3.30 was notable for supporting ATs and clones first time, I think.
It came out before MS-DOS 3.30 and was slightly more advanced, too.
DOS 3.3 was popular among both XT and AT users alike.
Yet I read online some old farts claim that DOS 3.x couldn't run on XTs anymore.
MS-DOS 5 was a relief and had that weird keyboard.sys driver.
Older users substituted it by using KEYBFR, KEYBGR, KEYBIT from older versions of DOS (such as 2.11 and 3.x).
Or some of the public domain equivalents.
Disruptor wrote on 2025-09-15, 11:25:
Please consider to stop at DOS 5.0 on an XT or AT.
It is a good DOS!
MS-DOS 5/6 basically have same kernal and are descendants of DOS 3.3.
Since MS-DOS 4.0 ('88) was such a desaster, it's understandable that all PC owners skipped it in favor of 3.3x or 5.
By early 90s,-no matter the PC-, using MS-DOS 6.xx wasn't any out of the ordinary.
Even some XT class notebooks had MS-DOS 5 in ROM at the time, already.
Sure, some people don't like seeing DOS 6.x on anything lower than a 386/486, but I think the reality back then was different.:
There had been people who ran MS-DOS 6.x on lower systems, maybe to use hard drive compression for example.
I mean, by 1994, MS-DOS 5 was very dated and limited compared to DOS 6.x.
Someone who had MS-DOS 6.x in the house surely used it on whatever PC.
Edit: I ran DoubleSpace on a PC/XT 4,77 MHz with 640KB of RAM (704KB in a few occasions).
The performance wasn't worse, the applications still fit in memory, I think that it even helped to lower disk i/0 overhead.
Video: https://www.youtube.com/watch?v=5XxOtHodSBU
DoubleDisk, the spiritual predecessor to DoubleSpace was from late 80s, by the way.
It was meant to be used on XT/AT class hardware, rather than 386+.
Edit: From a purely technological point of view, MS-DOS 5/6 have those advantages:
MS-DOS 5 introduced support for UMBs and HMA (a feature from earlier DR DOS 5).
MS-DOS 6.2x added the ability to skip all start-up files by pressing F5 at boot.
The menu feature for custom start menus was added in DOS 6, I vaguely remember.
Then there are utilities such as Defrag and so on.. Some appeared in DOS 6.x, I vaguely remember.
Edit: My apologies for my ever contradicting replies, but I simply grew up on MS-DOS 6.20, basically. On an AT (286). In the 90s. Edit: Early-mid 90s onwards, of course.
It may not seem period-correct to some, but I simply had such setup.
So to me, it was period-correct, of course! Because I lived through it (the time period).
In the diskette box at home we also had MS-DOS 3.30, PC-DOS 3.30, MS-DOS 5, MS-DOS 6 and MS-DOS 6.20 (but not 6.22 anymore AFAIK).
Edit: It could be that MS-DOS 6.2 was a step-up version, by the way.
Would make sense, considering that MS-DOS 6 was already at home.
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