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The NCR Decision Mate V - what is the usability and limit of this system?


Experienced Member
Jul 14, 2022
Hello everyone,

In a recent Ebay buy I got some "mysterious" PCBs included, as I found a 8237 DMA controller combined with
a Z80 CPU in the auction photos.
I was thinking, what's up with that?!

After some research I found that these PCBs are from the NCR Decision Mate V computer.
When I saw the photos I really regret to find only the mainboards and not the beautiful case with the CRT in it.
Still, this system intrigues me a lot because I love the Z80 and to see it combined with a system that can run as
an XT PC is quite fascinating. I might be interested in designing and rebuilding such a computer myself in
different form just for fun.

However, that strongly depends on how useful the most complete end result could become. I know much
depends on the BIOS software for example. I remember reading about DOS not running well on it? Did NCR
go too far away from the PC standard when you add the 8088 module? I mean, when I see the 8237, and the
8259 added on the module, I am thinking "XT", right? And having the interrupt and DMA, would it support other
interfaces such as sound and SCSI? Or even VGA?

Is there anyone here who could tell me more about what the limits are of the NCR Decision Mate V in its most
expanded form? I mean, with the most RAM expansion possible, the 8088 and interrupt controller included,
centronics, serial port, floppy drives, harddisk. I mean when you have all the expansions that this system could
support. Would IDE be possible? And could I use a normal AT Keyboard on the keyboard controller?

I would love to have a capable XT system which also includes a Z80 mode, that would be amazing!
I just wonder how compatible this DMV computer really could be.
I read somewhere that there were also color versions of the display PCB?
One of the two mainboards I have is fully populated but I don't have any display module. Which I could build
I am sure. I could try powering it up but I don't expect much besides maybe to hear some beeps or see some
diagnostic LEDs come on or to hear beeping when I type etc.

Kind regards,

Thank you for your reply pbirkel, I had not seen that text before.

I am hoping that I am lucky and that there are some members here who can tell me some things from their own experience.
But I am sure many of these computers are dead or became e-waste of course.
And some sitting in computer museums and collections etc.
I checked youtube but it's mostly just powering up the computer and running some demos.
I am looking for a technical perspective from a fellow technician.
Or perhaps a coder who could check the BIOS if there are problems.

I hope to get in touch with an enthousiast who has expanded his DMV to the limit and who can tell me how well DOS runs on it.
Maybe this system is too strange haha.

I have zero experience because I only have the mainboards, one populated and one with mostly empty sockets.
The only thing I have to go from initially is the schematics and what I can find online.

I will read the text in your link in detail, thanks!
I also downloaded some manuals which I will study.
But I think direct experience would me much faster and much more useful.

Kind regards,

Some more information's are there:

As the DM-V uses a true grafic processor ne 7220 it is therefore only rom / bios compatible to ibm and programms which write direct to the screen will not work like the Norton Commander.
Worked for NCR/AT&T from August of 1980 unit April of 1994. When the DMV (Decision Mate 5) became available I purchased a unit through an employee purchase plan, My system was a dual floppy color model with 256K of system ram. It came standard with the Z80 and Intel 8088 processor. The purchase price was $2500 and I financed it through the NCR Credit Union in Dayton, Ohio. A fellow NCR employee and myself were able to port RCPM (Remote CPM) so that we could run bulletin boards. The memory map was slightly different than a IBM clone PC. The DMV was not IBM compatible and would not run popular programs like Lotus123 (many apps made direct bios calls for performance improvements). The DMV ran CPM, MSDOS and Digital Research's CMP86. At the time of its' release there were many popular packages that it would run like Peachtree accounting and the complete MicroPro suite of apps like WordStar and DataStar. My unit had a the dark gray bezel which were the CAP (Corporate Appearance Plan) colors. They eventually adopted the DIN (Deutsch International Norm) color scheme as the primary manufacturing facility was located in Augsburg Germany. The other manufacturing facility was in Columbia, SC and I visited there one summer while on vacation. The plant manager shared a funny story with me where they had to shut down production for a few days as the CRT alignment was failing final inspection . They had tried everything to determine why the screen could drift out of adjustment, even tried hand carrying a unit from where it was originally adjusted down to final test area and screen was still out of adjustment. They called in engineers from Augsburg and they arrived and determined that the units were facing in different directions when adjusted and then finally tested in the QA process. Apparently the Earth's magnetic pull is strong enough to make the screen shift in one direction, remember these are CRT screens and electrons are affected by magnetic fields. Over the years I made several mods like replacing the 8088 processor with a NEC V20 and replacing the oscillator to increase the clock speed. Many of us increased ram by buying ram chips and stacking them on the memory module. I eventually got to where I needed a hard drive and the dual floppy DMV had no upgrade path to such. I also needed to have IBM PC compatibility as I was writing software to run on IBM clones and wrote routines to write directly to the video ram. I had purchase a Xerox clone for around $1000 and ended up selling my DMV to a gas station owner in Gainesville, Fl. He had one and needed a second one. I learned so much from this machine and it kind of lead me down the path to where I am today.
Maybe the harddisk option arrived later, but there definitely was a DMV with a 10MB internal harddisk, and an external cabinet with up to two MFM drives ... if you were purely working on MS-DOS, a disk could be formatted to 20MB capacity.
Hi Vwestlife,

Thanks for your message. I didn't see this model more carefully before, it has a similar case design which is beautiful.
I have studied the PC4i technical reference manual, and found that in this model they have switched things around.
The base CPU is a 8088 in this model. Which is basically very similar to a PC. I browsed through the manual and found
no reference to any Z80 expansion. So this model is not really too interesting for reproduction. It's really the case design
which makes the PC4i model interesting, especially if it's a color screen model.

Anyway thanks for your video link, it was still quite interesting to look at it.

Kind regards,

Hi Fritzeflink,

Thanks for the link! The photos on this website of the internals of the DMV are really great!
I love to see the CRT etc inside the case!

Recently, I have modified a old Philips TX 11 inch black and white CRT RF television into a composite monitor.
I did a lot of work to clean and wash all the internals and remove all the PCB components for television and
change the input to composite video. I tested the video display on my XT PC using a ATI small wonder,
however I found the display not aligned properly. And this tv was too limited in adjustment circuits to change
the alignment. Maybe later I will modify the horizontal deflection circuits to include more adjustments.

Kind regards,


That is a great post about your experiences, I love the story, thanks! Those bulletin boards sound like a
really fun application to use. I can imagine that CP/M was much more compatible to the DMV because
of the Z80 CPU. This may be interesting to look into.
Previously I also developed a ATX Z80 PC inspired by the RC2014 project and the awesome ROMWBW
project. ROMWBW is really impressive, it makes this Z80 system truly amazing. I believe that the 7220
graphics chip may be compatible with the ROMWBW project and it may be possible to compile it into the
ROM, I should look this up. Though I already made a TMS9918 graphics output on it. I am still working
on this system and because I have several projects at the same time, I didn't get around to starting
development for a custom graphics adapter on that system which I am still planning.

What I am basically also doing in my design work is to further my experience and perspective on different
systems. This may give me more insight into how I want to proceed further on the Z80 system as well.
What I wanted before is to create a Z80 PC which can measure up with an XT, which is a tall order of course.
The real limitation is especially in the graphics display area. There is still no VGA adapter available for the
RC2014 project. I mean, not the type of VGA adapter I would wish to use, I mean similar or better than in a

Lately I am really fascinated by CRTs. I mean, they look really retro and awesome, and give you a different
experience when you use it. After modifying my B/W TV into a monitor, I watched an old Bond VCD movie
on it just for the retro experience and to test the quality!

It's funny you mentioned about the earth magnetic field, I also made my own experience before. What I did
was I owned an old Nordmende color CRT TV and wanted to play my arcade game Tiger Heli on it, so I
rotated the screen upward. After playing the game for a long time, I changed the TV back into the normal
orientation, only to find that the colors were distorted somehow. I believe it's also due to the earth magnetic
field. After a while it seemed to return back to normal display when being in the normal orientation for longer.

Indeed expandability is an issue, I thought as much already. It's really useful to read about the different
software packages that can and can't run, thanks! This gives me more info about what range of software and
hardware is possible on this system.

It's a pity that even a hard drive was not an option. I think only a Winchester drive? But that seems very limited
and not really useful anyway now. Though it might be possible to reverse engineer the Z80 BIOS and add a
PPIDE to the system. This is really beyond my current scope of expertise though.

Great to know the DMV got you started. For me it was a ZX81 (TS1000), which was of course a extremely limited
computer compared to the DMV. Anyway, to gain an interest into computer technology is always a good thing
for anyone, I feel.

I will think carefully about what I want to do in a possible DMV project. The idea of combining Z80 with 8088 still
fascinates me a lot, it is really interesting. To design a derived system from the DMV will let me gain more insight
into combining and switching between different main CPUs in a single system, which is also a great experience to

Kind regards,

Hi rfka01,

Yes, indeed I just checked the technical manual of the DMV and found an option for a Winchester harddrive listed.
Though of course now I believe this would not be useful at all. If I could find an IDE interface that would be much
more interesting and useful.

I never looked into the Winchester drive interface, since there are also not many of these drives around now, and
also no modern replacements either.

Kind regards,

Hi fritzeflink,

That is great, I just checked the contents in more detail, it's a lot of information, also diskette images and manuals.
I downloaded the manuals and I will read through them to get a feeling for the system what it would be like when
using it. Very useful, thanks to everyone involved in creating the content!

Kind regards,

Maybe the harddisk option arrived later, but there definitely was a DMV with a 10MB internal harddisk, and an external cabinet with up to two MFM drives ... if you were purely working on MS-DOS, a disk could be formatted to 20MB capacity.
Yes - I have one in my basement with the wd1001-05 harddisk controller and a NEC D5124 10MB harddisk. Even there was an adaption for an external harddisk with the wd1002 controller. The black mitsubishi floppy drive in the 1st picture is a temporary replacement.


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I was given a DMV a few years back and haven't yet tried to resuscitate it. It does have the notable feature of a dozen missing keycaps :-{. They're non-standard low-profile square keys with a raised round concave top; example photo attached. Does anyone know of a replacement source?


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Maybe the harddisk option arrived later, but there definitely was a DMV with a 10MB internal harddisk, and an external cabinet with up to two MFM drives ... if you were purely working on MS-DOS, a disk could be formatted to 20MB capacity.
Yes, you could order a model with the 10mb internal HD from the beginning I just don't think it was an upgrade option that could be purchased later. I had a buddy that ordered it with the hard drive option 512k of ram and every OS available including the "P" system.