• Please review our updated Terms and Rules here

MS-DOS 2.25: was it ever released or was it vaporware ?

P

pcdosretro

Experienced Member
Joined
Jun 23, 2019
Messages
162
Location
San Francisco Bay Area
Was MS-DOS 2.25 actually released or was it vaporware ? MS-DOS 2.25 was widely documented to provide early DBCS support for Korean and Japanese character sets and was presumably only released in those markets but there is apparently no known evidence of such a release. There are conflicting release dates for it, some sources claim April 1984 while others claim October 1985. All sources say that MS-DOS 2.25 added INT 21h function 63h (which was originally referred to as "Hongeul" in the DOS source code) though MS-DOS 2.x is known to only support INT 21h functions up to 58h (which was added in MS-DOS 2.11). DOS 3.0 added functions 59h-62h which supposedly are not in MS-DOS 2.25. Could Microsoft have simply put the info out there in an attempt to drum up business in the Far East market ? Could there have been so few OEMs in the region using it that MS-DOS 2.25 is simply lost to time ?
 
Chuck(G) said:
If you could find a PC JX owner, I suspect that you'd also find a copy of 2.25.
Click to expand...

Maybe. The PC JX was also released in Australia and New Zealand so it's unlikely they would have MS-DOS 2.25. Also the PC JX supposedly came with PC DOS 2.1 and as an IBM computer it would have never shipped with anything other than PC DOS. As far as I know there was never a "PC DOS 2.25" as IBM wasn't interested in internationalization at the time.
 
The PCjx was only released in Australia and New Zealand when it failed in Japan and IBM had much inventory to get rid of, so those came later. The PCjx definitely supported Kanji on day 1, you can see this in the promotional literature. Exactly what DOS version provided that I don't know, but it wasn't DOS 2.1, and it seems unlikely that IBM would go backwards in terms of bundled DOS releasing to an English-speaking country. The PCjx was an enhanced PCjr and likely needed features not present in 2.1. Chuck's advice is relevant.
 
Chuck(G) said:
Hmmm. Could have been an OEM version that never saw the light of day.

Page 2 mentions PC-DOS 2.25 being sold by Atari
Click to expand...

That's the first I've ever heard of a "PC DOS 2.25" and I worked on PC DOS at IBM. IBM certainly never acknowledged the existence of such a version.

Did the Atari ST x86 add-on board ever actually come out ? There was a lot of stuff planned during the Tramiel era of Atari which never saw the light of day. Atari also planned on making an Atari 1600XL hybrid system which would have had a 6502 for Atari 800/800XL compatibility and an 80186 for DOS compatibility.
 
krebizfan said:
A picture of the disk provided with the IBM JX in Japan shows a printed version label of K2.2. How this compares with the 2.25 is information I do not have.

http://msibata.org/ibmpc/image/jxdos.jpg
Click to expand...

That's interesting and I wish I had an image of that disk for analysis but one thing to consider: DOS didn't get 3.5" 720KB support until DOS 3.2. Theoretically previous versions of DOS could use half of a 720KB since it would appear like a 360KB floppy to them. The PC Convertible was the first PC that I know of to use a 3.5" 720KB floppy drive and it shipped with PC DOS 3.2.
 
PC JX was released in 1984 with 3.5" drives:

500px-IBM_JX.jpg


Granted, they were 720K, but there you have it. Note also, that said drives are half-height, not the later one-third (of a FH 5.25" slot) height drives. I wouldn't be at all surprised if the drives were also the 26-pin variety.
 
While the IBM JX started off only able to handle 360kB on its 3.5" drives, the ROM version of MS-DOS 2.11 available with Toshiba T1000 could support 720kB formats on its 3.5" drive.
 
pcdosretro said:
DOS didn't get 3.5" 720KB support until DOS 3.2. Theoretically previous versions of DOS could use half of a 720KB since it would appear like a 360KB floppy to them.
Click to expand...
The Philips :YES uses an adapted MS-DOS 3.10, which does support 3.5" 720 KB floppies.
 
Depends on what you define as "DOS/MS-DOS". We were using 800K 5.25" drives on MSDOS 1.x and 2.x--and I have the disks to prove it. Of course, we used our own IO.SYS for an "not quite PC compatible system". I'm sure that other examples abound.
 
A site devoted to the IBM 5550 line lists many versions of PC-DOS that are not listed in the standard version lists. I might suggest contacting them and seeing if there is any further information especially in regards what is referred to as H2.6 the Hankul version. I suspect some of the issue is that 2.25 would be an internal MS version number which is not the version number used on the label.

http://ibm5550.na.coocan.jp/soft_os-e.html It is in English so presumably the site operators will be easier to communicate with.
 
The Kaypro 2000 is my personal favorite for 3.5" 720k. Completely identical disks to later standard 720k. And as chuck mentioned, 800k 5.25" disks on my Eagle 1600 (but I still need to find a copy of Eagle's DOS 1.25). In DOS 2.x it is all just controlled by a drive geometry lookup table based on the boot sectors media type byte. I've even edited Kaypro's DOS 2.11 to recognize 1.44mb disks just by changing one entry.

So OEMs could and did support many drive types.. but the odd thing here is this is from IBM, and 720k support was not official until IBM PC-DOS 3.2. If it had Japanese fonts in it then it was clearly not standard IBM PC-DOS anyway. They certainly could of modified PC-DOS 2.x to work with that, but it would be great to know what exactly is actually on that disk.
 
I can't add anything really fruitful to this thread, but for the sake of "time stamping", I was working for the feds inside the beltway back in 1986, and came across a set of two 720 3.5" diskettes with DOS 3.3. This was the first time that I encountered DOS on in the 3.5 format. In 1985, when I purchased my Tandy 100, all of the software was 3.5.
 
You must log in or register to reply here.
Back
Top