PC-DOS 3.2 for 5150

[maxtherabbit]

Thinking about downgrading my 5150 to DOS 3.2 to save a few more kB of conventional. Any reason not to? Looks like all of the changes in 3.3 aren't really relevant to my configuration anyway - am I missing anything? Is there any significant amount of software that would balk at a DOS version sub 3.3?

[Chuck(G)]

You're probably okay, DOS 3.0 was really the watershed version. 3.3 added more features for little extra cost, so it was more popular.

[the3dfxdude]

I have come across IBM software that requires PC-DOS 3.3. But if that is something you need, you'd just deal with it.

It's easy to keep a boot disk for 3.0 and 3.3, if you have both anyway; that's what I do.

[Trixter]

Thinking about downgrading my 5150 to DOS 3.2 to save a few more kB of conventional. Any reason not to? Looks like all of the changes in 3.3 aren't really relevant to my configuration anyway - am I missing anything? Is there any significant amount of software that would balk at a DOS version sub 3.3?

What is your full 5150 hardware configuration?

[maxtherabbit]

256kB system board
Paradise auto switch EGA
Ast 6 pak (640kB fill)
360kB drive A 720kB drive B
ST225 drive C MM212 (10MB) drive D
LTEMS card
WD8003 NIC
V20/8087

[Trixter]

If you only have a 10Mb drive, run DOS 2.11 and you'll get even more free memory back.

If you really want to maximize free DOS RAM, run DR-DOS 6 and load HIDOS.SYS and you'll get ~612K free, as it can take advantage of your EMS card to create UMBs and load the DRDOS kernel up there.

However, with 640K, *AND* an EMS card, the last thing you need to worry about is a few more K of free DOS RAM. Your 10MB drive won't let you store any software that can actually maximize the full 640K, other than spreadsheets and word processors, so the exercise is somewhat pointless. I wouldn't bother.

640K, EMS, NEC V20, 8087, EGA... but limited to a 10MB drive? Curious why you chose that build.

[maxtherabbit]

The boot HDD is a ST225 which is 20MB. 10MB is the secondary HDD.

As for the configuration, I didn't exactly just choose it out of the clear blue. I've had this machine for over 20 years and it's been gradually evolving. Only recent changes are the addition of the 720kB floppy and the EMS card.

3.2 is the minimum DOS version to support the DRIVPARM config directive that I use to support the 720kB drive. I'm getting about 585kB free now with DOS 3.2 and my EMM, packet driver, and DRIVER.SYS (for an external floppy) loaded. So I'm satisfied, that's plenty for anything

[Chuck(G)]

Don't sweat the storage--my first 5150 hard drive was 4MB--a Shugart SA1000. I got plenty accomplished.

[Eudimorphodon]

LTEMS card

I assume that's the Lo-Tech 2MB EMS card? If it is and you want to test a random thing some joker on the internet came up with I wrote a little point-enabler dingus, "ems2umb.exe" to set up a card compatible with the LTEMMS card to give you 64k of upper memory space without having to load the resident driver. The driver as compiled will only work if the I/O of the card is set to the default 260h.

Anyway, using this lets you use USE!UMB.SYS to do upper memory stuff with MS-DOS 5 or later while saving the ~5k or so the EMS driver takes up. Obviously you don't get to use EMS when using it for this.

[maxtherabbit]

Yes it's the lo tech. I'm content with the amount of free memory I have now and don't want to sacrifice 2MB of EMS for 64kB of UMB. I saw your tool before and it is cool though