new find: an Intel MDS 800

From: Joe R. <>
Date: Tue Oct 26 20:13:17 2004

Hi Scott,

   Congradulations on buying a "real" computer instead of a toy like the
SB-180 :-)

   I'm REAL familar with the MDS-800

  Can you make a list of the docs that you got. Here's a list of the ones
that I have; <>. I have more
but haven't had time to update the list.

At 07:00 PM 10/26/04 -0500, you wrote:
>I recently acquired an exciting new (old) machine, an Intel MDS 800,
>known as the 'Blue Box.' It's the 1975-era 8080 based box that kicked
>off CP/M.
>My particular machine was intended as an 8051 ICE box, it has the 8051
>emulator pod and external PROM programmer.
>The system came complete with a big box of what appears to be complete
>docs and a lot of software on 8" disks. There are four or more
>different versions of IRIS,

   That should be ISIS (Intel System Implementation Supervisor) not IRIS.
The ISIS disks should also be bootable.

 a disk labeled 'CPM' which I hope is a
>boot disk, and multiple versions of other Intel tools, including the
>targeted 8051 development tools.
>I paid a fair amount for this system, and am going to go slowly at
>bringing it up. It's been stored a long time and there's a troubling
>amount of surface rust on some of the screw heads and exposed

   Take it apart and clean it. I use Lime-Away on steel screws. It contains
phosphoric acid and is similar to Naval Jelly. >>>>Make careful notes
about what cables go where and what cards go in what slots. They're not
entirely interchangeable. Many of the cards come in sets of two or three
and one particular card of the set has to go into an odd numbered slot and
the companion card has to go into the next higher numbered slot. This is
because Interrrupt signal is wired to different pin numbers in the odd and
even slots. ALSO the Front panel controller MUST go into slot one and the
CPU card MUST go into the second slot. I BELEIVE the RAM cards and Monitor
card can go into any slot.

>I've popped it open and some of the ICs (mostly TTL) have corrosion on
>the leads. I have a few opening questions for others who have
>restored hardware in similar condition: should I remove the corrosion
>on IC leads, or do I run the risk of 'removing' the leads.

  I believe I'd leave them alone until I had the machine working. Then,
perhaps, I'd clean them one board at a time. That way I'd know what board
the problem was in if something screws up.

>circuit boards look really good, so worst-case I will replace some of
>the chips.
>What is the opinion about this kind of servicing? The chips in
>question are all (so far as I have investigated) common 7400 series
>(some Schottky) TTL gates. Do people consider it as 'damaging' to the
>'credentials' of a piece of classic hardware to replace chips with
>others with significantly different date codes?
>This is going to be a long term project for me, I fear, because I want
>to do it right. This machine has a built-in CRT display

   ???????????????? What! The MDS-800 doesn't have a display. It uses a
terminal. Oh wait. I'll bet you bought that mislabeled one off of E-bay.
Let's see, here it is
&rd=1&ssPageName=WDVW>. If this is what you bought then it's NOT an
MDS-800. Look at the pictures of a couple of my 800s at the links at the
top of the message. This is a LATER MDS-220. Here's a page that describes
the differences between the various 2xx models;

   The 2xx are similar to the 800s but have a built in CRT and a detachable
keyboard. They also have a space for a single disk drive but not every
model includes the drive. The drawback to the 2xx (IMHO) is the lack of
slots. They only have five slots where the 800 has 18. You'd think 5 slots
whould be enough but all the ICE units use two cards (some of them use
three!) A Double Density disk controller uses two cards. Most RAM cards are
only 16k so you need at least one slot for that or as many as four. Then if
want to use an 8086 CPU you need a slot for that card (in addition to one
for the regular CPU (8080 or 8085) card. That's probably why most 2xx
machines come with the optional expansion chassis. BTW there is a built in
disk drive controller. The internal drive is USUALLY hooked to it BUT if
you install the optional Double Density Disk drive controller you can hook
the internal drive to it.

   I'm curious about your aftermarket drives. Are you SURE that they work
with the MDS? Intel monkeys with two of the signals inside of their drive
box (the box, not the drives themselves). IIRC one of the signals is the
READY signal from the drive and the other is the head load or spin signal
from the CPU to the drives.

 so I might be
>forced to do some (something I almost always refuse to do these days)
>video monitor troubleshooting.

   Maybe I've been lucky but on my three 2xxs the monitor all started
working after I moved a couple of pot controls. It seemed like they had
built up a spot of corrision where the wiper was sitting but it cleaned up
after I moved the wiper a couple of times.

   BTW were you aware that that EPROM programmer uses a 4040 CPU? I hate
to think of all of them that I passed up before I learned that.

>The machine has a built-in 8" floppy, which I assume is the
>low-density original, and an expansion case (third party) with two
>newer and higher density drives.

   The density is a function of the controller, not the drives.

>Is there a source for new or NOS 8" floppies out there?

  Yeah. I found a sealed box of DS DD ones just last week. BTW all the
drives for the MDSs (both 800s and 2xxs) are single sided. The low density
ones use the "standard" CPM format but the DD one have a format that's not
compatible with any other machine that I know of.

One thing for
>certain that I'll be doing early after getting this machine up and
>running is a backup of all the media that came with it (a fair amount,
>probably 30-50 disks, many of which are Intel branded originals).
>Lots more questions and comments likely to come on this project.

   Ask away! The MDSs are one of my favorite machines.

Received on Tue Oct 26 2004 - 20:13:17 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:37:24 BST