Mikbug info? - test-drb@ccmp.vtda.org

28 Mar 1998

Bill Yakowenko &lt;yakowenk(a)cs.unc.edu&gt; wrote:

...
 >From very nearly the first day I bumped into a
computer, I've
>been finding sporadic references to MIKBUG, an early monitor
>ROM for 6800 machines.  For instance, most of the older 6800
>monitor ROMs (SWTBUG, SMARTBUG, others?) claim preserve MIKBUG
>entry points.  And a lot of the programs in Motorola's ancient
>6800 freeware archive refer to it.  (That archive can be found
>at this URL: http://www.mcu.motsps.com/freeweb/pub/usergroup) 
...
 >But I've never seen one, or any any real
documentation for
>one.  Can anybody out there help me find any of this stuff? 
>Of course I'd be happiest to find a binary image, source code,
>and whatever docs originally came with it.  But I'll take
>whatever I can get.  As it is now, the best I can do is to
>extract some of its defined entry points from definitions
>in those freeware programs.
>
>	Thanks!
>	Bill. 
allisonp(a)world.std.com (Allison J Parent) wrote:

...
 Same here.  I have a M6800D1 and MIKBUG but no source
listing. The 
function is a very simple program loader/debugger. What was interesting 
is the code was written so that routines like TTYin, TTYout, PRINTCHR
and PRINTnum could be called from external programs.  Saving some coding 
effort. 
...
 Allison 
The first computer I built was a 6800 SS50 bus machine.  Of course I wanted
to maintain compatiblity with MIKBUG.  So I requested from Motorola their
Engineering Note 100 titled:

    MCM6830L7 MIKBUG/MINIBUG ROM

And the good news is that I still have the Engineering Note.
The first 10 pages describes a little hardware, address decoding and address
spaces used. The next 8 pages is a full assembly source listing for MIKBUG.
The next 4 pages is the listing for MINIBUG.

MIKBUG occupied 512 bytes starting at address E000, 
it used 128 bytes of ram starting at A000 for scratchpad and the stack,
and a PIA at address 8000 for serial interface to a terminal.

I rewrote the code to move the I/O bus from 8000 to F400,
and the ram from A000 to F000.  With the original addressing scheme there was
only room for 32K on contigous memory, AND WHO WOULD EVER NEED MORE THAN 32K
:)
I recoded so that I could have 48K of ram and 12K of Eprom.

I also recoded it to use a parallel keyboard interface and to drive a Percom
video board.  Terminals were not cheap then.

I later obtained a hex dump listing of a disassembler.  Given the custom of
always using the standard MIKBUG entry points, I was able to figure enough
about the disassembler to have it disassemble itself and later to 
disassemble an assembler.  Given that info I rewrote both the disassembler
and the assembler and then later assembled a disk operating system from a
source listing published by some company that had one copy of the book left
when I called and ordered it.  The DOS was called CP/68, not to be confused
with CPM/68, although CP/68 appears to have had its roots in CPM.

And now here it is years later and I don't even know how many computers
I've got, but I always look back at the time and effort that I put into
that first machine.  I sometimes feel I put more into it than I got back
in terms of doing some productive, but then again what I learned from
that has proved worthwhile time and time again.  I know that there are 
those on this list that are barely out of their teens, and quite frankly
I wonder sometimes what their fascination is for these old machines.  Then
again what they will learn from resurrecting some old beast will be worth
a lot more than what they learn in some course somewhere.  The graduates
...
 from the 'school of hard knocks' always seem to
be better. 
Enough of my ramblings.  I looked around the above mentioned web site and
did not find Eng Note 100.  I would suspect that it may be out there
somewhere.
If not, and you're unable to get a copy from Motorola, I may be willing to
copy
the Eng Note and send it out.  I just hope I am not deluged with requests.

Mike Thompson