IBM 5100 Restoration in progress

Santo Nucifora santo.nucifora at
Wed Mar 18 07:05:30 CDT 2015

Sorry about that.  Here's the registers:

It was an inline image and I can still see it when I look a the email I
sent :)  That's a direct link.

The display of registers is consistent from first start up and through

I did want to thank you also for the terminator clarification.  I changed
my page.  I also looked at the IBMparts.txt reference chart.  That's
exactly what I needed.  I do have some rusty logic chips that cleaned up
decently but I don't trust them exactly since the previous owner turned
this computer on with the rust bridging pins.  He claimed it worked with
the Register screen on.  I knew otherwise. All of the "cans" looked good

Thanks again.  I do need to look at the Maintenance manual when I get home
to line up the registers and see if $FF is in the right one but you can
probably tell that pretty quickly with the picture.

Thanks for looking.

On Wed, Mar 18, 2015 at 7:54 AM, Christian Corti <
cc at> wrote:

> On Wed, 18 Mar 2015, Santo Nucifora wrote:
>> Where did you find the code for the Bring Up tests?  I would love to have
>> a
>> look.  The 5100 Maintenance manual is not very specific and certainly
>> doesn't have code in it (unless I missed it).
> I disassembled it myself. You can find the disassembly on our FTP server,
> too:
> But as mentioned, all information refer to the 5110.
>  My registers looks like this:
> I don't see anything... was that an attachement or inline picture?
>  You'll notice that the first two characters in second line is not right.
> They are absulutely right! This means that the processor is running
> (executing a halt instruction that in reality is a jump to itself). What
> you are seeing is the program counter (register R0) changing. I you put the
> machine into single-step mode (there's a switch in the machine under the
> cover) you can step the instructions one-by-one.
>  Sadly, it's gotten a little worse after taking this picture so lines 5 and
>> 6 have some garbling of the dots. Since I was seeing text, I didn't
>> suspect
> If all other characters are ok, what you describe as garbling are just
> changing data bytes.
>  the display card right away (again, not knowing the machine) but it may be
>> bad RAM on the display card.
> I wouldn't suspect the display card, too.
>  I'll refer to your  IBMparts.txt file and see what is on that card.  If
>> you
>> do see anything else in the registers, I'd be very happy to hear your
>> thoughts.
> Could you put the picture on your web site or send me an email? And please
> also make the following readable screenshot:
> 1. Put the machine into single-step mode
> 2. Press RESTART
> 4. Make photo
> This is the hex dump of the first 512 bytes of the Executable ROS. At
> least that's how it works on the 5110.
> Christian

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