Help with IBM 5100 - ROS error

From: Dave Dunfield <>
Date: Mon Aug 16 17:08:17 2004

Hi Guys,

Now that the SuperPET's are off the bench, I have moved on the 5100.

This is an IBM 5100, BASIC only, 16K model - I received it about a week
ago. It was reported working the last time it was powered up (I have a
picture of it taken then with a BASIC program on the screen), however it
has been stored in an attic for quite a few years since then.

The machine runs, however the "BRING UP" program is reporting an error
in the non-executable ROS content and CRC test. At least thats which I
understand from the maintenance manual.

It gets as far as the 'I' test, then lights the PROGRESS-CHECK light.

The screen displays:
18 07

  (Bottom line of display)
A B C B ~ N_ 13 EZEP (Z and P are underlined)

According to the maintenance manual, line 1 cols 1 and 2 should contain
the ID of the module it is looking for (18) and 5 and 7 contain an error
code (07).

I have not been able to determine what '07' means ... Perhaps its in the
manual, but I have not found it yet. (Please bear with me, I haven't seen
a real live 5100 in aver 20 years, and I have never worked on one before).

I have tried removing and reseating all the cards (which is very unplesant
as the rubber/foam which supports then when they are in their normal
"upside down" position is about the consistance of tar on the surface,
which has glued itself to the faceplates of all the cards - I'll be looking
for a good way to replace this eventually).

Anyone have any experience with reports of bad ROS - is there any other
cause (power supply tolerance etc.).

I know this is a long shot, but anyone have a unused 5100 ROS? (perhaps
from an APL upgrade or a dead machine) ... (I'd really like to find a full
Anyone have the code?
Anyone ever tried making a substitute?

According to the manual, you can get into the level 1 diagnostic mode
by pressing either:

  Cmd *
  - or possibly -
  Cmd + / Cmd - / Cmd *

Page 3-10 indicates just 'Cmd *' while page 3-15 indicates the longer
sequence - neither does anything on my unit - am I doing it wrong, or
is this a function in the non-executable ROS, which is not being allowed
due to the error? (Does it even recognize this sequence when in the
process-check state, as according to the register displays it appears to
be halted?)

Any help / insight would be greatly appreciated!

dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools:
com             Vintage computing equipment collector.
Received on Mon Aug 16 2004 - 17:08:17 BST

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