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Merry XMAS and a happy new year 2020 ! 
Wednesday, December 25, 2019, 02:30 PM
Posted by Administrator
While surfing around and looking for a nice xmas demo, I found a 64KB DOS demo from an event named "The Party" in 1996. It has a nice soundtrack and it has some action on the screen ;-)

See related link below for a download possibility.

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A real classic computer game - ELITE ... worth to be revisited ! 
Sunday, September 29, 2019, 11:30 PM
Posted by Administrator
This is really a classic computer game, famous or at least well known, but nowadays almost forgotten. ELITE was one of the first open world game for PCs and home computer.
That means almost eternal game fun/game play, if you want.
Published from Acornsoft in 1984 first, Ian Bell and David Braben created this space simulation/trading game with some real new features for its time, like wire-frame 3D graphics (MCGA version has textures/filled areas already!).
It can be played on several platforms, and so also on PCs running MS-DOS.
The CGA version (which runs not quite bad on a standard XT) looks a bit ugly, but is well playable, too:

Surprisingly, EGA and VGA version (Elite Plus) does not visually differ.



Only the MCGA version (Elite Plus) looks way better:

The best of all - this game is meanwhile legally downloadable, see related link.
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Further tests with Concurrent DOS 386 3.0 (still with PCem) 
Sunday, August 25, 2019, 02:00 PM
Posted by Administrator
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 !
The disks there didn't had the correct boot sector - but nobody there recognized this.
I downloaded working disk images from, 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 disk image. Or just copy the boot sector of the disk image to the one from - 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.
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Some tests with Concurrent DOS XM 6.01 running with PCem 
Sunday, August 25, 2019, 12:00 AM
Posted by Administrator
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:


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.
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My Yodobashi (Microvoice) Formula-1, with build-in eprom programmer 
Saturday, July 27, 2019, 10:25 PM
Posted by Administrator
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:

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