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Another test round. Tried it first with an emulated 486. Didn't worked.

Then, I choosed to emulate a Compaq Desktop 386, which was somewhat a success.
You have to look for a SETUP disk first, because there is no "build in BIOS setup".
I still got a "memory mismatch", because the setup program didn't recognized the emulated RAM amount, but you are able to press at boot time F1 to continue anyway.
Then I was able to install it - but not with the disks from winworldpc.com !
The disks there didn't had the correct boot sector - but nobody there recognized this.
I downloaded working disk images from bitsavers.org, they were in IMD format, but you can convert them with IMDU to IMA/IMG files. But the "N.CMD" was missing, get it from the winworldpc.com disk image. Or just copy the boot sector of the bitsavers.org disk image to the one from winworldpc.com - a bit ugly, but works too.

I was a bit surprised it returned DOS version 3.31 (NOT 3.30), see here:

Had to patch CHKDSK from DOS 3.30 to run it, free memory looks similar to Concurrent DOS XM:


I tried PSION CHESS again (choosing CGA display), and it looks better (correct color palette now). Also, if you switch with Ctrl-2 to the next window, I was able to start programs like FM, showing the free memory:

As you can see, there is also RAM occupied from the "FM" process, in parallel to the still running game. You will not be able to switch between EGA or VGA games still.

Related link leads to a Youtube video with an advertisment of Concurrent DOS.

Because I was curious about the capabilities of Concurrent DOS XM 6.x running on a PC/XT clone (emulated with PCem), I tested a few things.
I was able to install it using PCEm 14 on an emulated hard disk drive (20MB), it looks not too unusual:

and


Pressing ESC let you see the pure command prompt again.

I was curious about two things now:
1) How many RAM is free for executing programs
2) Am I able to run games with graphics screen (e.g. for CGA)

I tried (after running CARDDECK, which sorts the screen windows) the build in CHKDSK first:

Unfortunately CHKDSK here does not report free RAM :-(
So I tried CHKDSK copied from IBM PC-DOS 3.30 (why 3.30 ? because Concurrent DOS XM reports Version 3.30 (1E 03 when executed MOV AH,30 and INT 21 with DEBUG), and it shows up the free RAM:

Not too bad but significant less than with PC-DOS 3.30 only.

Also, I tried to run CGA games (do not try EGA or VGA games), e.g. PSION CHESS.
It surprisingly worked, but was shown with a wrong color palette.
Also, if you're running a game, it depends on the cooperation of the game itself if Ctrl-1, Ctrl-2 a.s.o. for Windows switching will work. In this case, it worked, but you are not able to execute other programs, only build-in DOS commands like DIR. This is because there is no (conventional) memory left while running a DOS game.

Have to test Concurrent DOS 386 now, may be this DOS version is better suited for running simultaneously more programs.

This is a *very* nice portable CP/M computer, really rare and perhaps unknown for many, but still worth to be mentioned. It has a Z80 CPU running at 4 MHz, has a build-in eprom programmer (up to 27128) and, like many other CP/M computer, 64KB RAM. It has two 40 track double sided floppy drives (~ 346KB capacity + system tracks), and it has even an external connector for 8 inch floppy drives (the standard IBM format with 77 tracks is used).

Also, it has an integrated thermo paper printer (no chance to get such thermo paper rolls anymore).
Although it's screen is only 5.5" sized, it has a really clear and crisp display:

Recently I got also a Bondwell 8T, which is an early PC/XT compatible Laptop (with LCD display, but still heavy). It has a nice keyboard, and I got also an external floppy drive (Model 112B) for it.

This laptop has a special unique feature, it has a chipset, which make it possible to use the rest of the physically existing 1024KB RAM above the 640KB limit.
Unfortunately you will NOT find the specific Expanded Memory Manager driver while using Google, so I tried several other solutions, Quarterdecks QRAM included. Nothing worked.
But I found a photo from the same laptop in a forum, and I asked the one who posted it.
Finally I got the driver, and guess what name it has ... it's always the same filename for all machines, but the program file differs always, too (because of the different hardware) - EMM.SYS. If you do not have this specific one, you can't use the extra memory, which is very important if you don't have a hard drive (this laptop didn't had one).
But if you have the driver, all goes positive, and I was even able to load a RAM-Disk driver:

I had to use TURBODSK 2.2, because RAMDRIVE.SYS does NOT support expanded memory or if you're lucky and got the last version (from MS-DOS 4.01), an AT-machine (286) is minimal required.

Also, I tested the ability to display graphics, not too bad but NO COLORS, so a dithered picture is necessary - see here:

The specific EMM driver can be downloaded here, see "related link".

... so be sure to visit the new URL http://www.forumcpm.gaby.de/index.php .
Although it's german I am sure also english speaker can write entries and will get an answer in english for sure, if necessary.
Her old forum will be converted into a static web page.