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From: ervin@pinbot.enet.dec.com (Joseph James Ervin)
Newsgroups: comp.sys.handhelds,comp.sys.hp48.d
Subject: Re: Machine Language Info
Message-ID: 
Date: 30 Apr 91 13:08:01 GMT
References: 
Sender: guest@ryn.mro4.dec.com
Reply-To: ervin@pinbot.enet.dec.com (Joseph James Ervin)
Followup-To: comp.sys.handhelds
Organization: Digital Equipment Corporation
Lines: 84


>I vaguely remember someone posting some highly recomended reading material
>concerning machine level programing on the HP-48.  Could someone, preferable
>the orginal poster or a copy of the original post, please give me a second
>copy of that information.  At the time I wasn't interested in machine level
>programming; however, I have recently decided to explore the internals of
>my HP-48SX.  Any advise on good sources of information would be great.  I am
>most definitely a beginner.  The only assembly language experience that I
>have had was last term in my one of my EE classes involving the Motorola
>MC6809.  Thanks in advance.
>
>Jason P. Meyers
>JMEYERS@mtus5.cts.mtu.edu
>


Ah yes, the good old 6809.  Actually I grew up on the 6800 family of
processesors, and I understand that the 6809 is considerably more advanced than
the 6800's I used back at U-Maine.

Anyway, I believe that I am the original poster to which you refer.  Here is a
copy of the information you requested.  Enjoy!

>>>Joe Ervin

***********************************************************************
To all who are interested about doing machine language programming on the
HP48SX, and who have been frustrated at trying to find information on how
to do so:

To my knowledge there is no official documentation or books which describe
how to do ML programming on the HP48SX.  Here are some sources of
information that have served me well.

First, check out Alonzo Gariepy's notes on the  Saturn processor, which is
the processor HP used in the 28 and also in the  48SX.  This will give you
a decent introduction to the instruction set and the basic architecture of
the processor.

Then, you should read Alonzo Gariepy's notes on doing ML programming on 
the HP48SX.   These notes provide some useful information, and give some 
decent examples of how to do things.

Next, I recommend you take a look at the internals description by Derek
Nickel. This gives a decent explanation of the different data types used 
in the 48SX, and how they are each represented.  Of all the internals lists
that have been posted I believe that his has the best descriptions of  the
various object types, their prologs and how they are stored.

Next, I recommend that you get the list of internal addresses that Jake
Schwartz posted to the net.  This gives a good description of all (?) the
known  internal addresses and what they do.

Finally, I suggest you get the Star assembler.  After reading the README
file and the STAR.REF files which come as part of the Star  assemlber, you
should have a pretty decent feel for how to program the 48SX. STAR was
written by Jan Brittenson, and he has put in a good effort to make it
fairly transportable.  I was able to compile and run it on a VAX/VMS system
without requiring much effort on my part.

For some more involved examples of machine language code, check out the
sources for CHIP-48.  This also gives some good hints on how to access the
keyboard and display.

Lastly, let me make one more suggestion.  READ THE DOCUMENTS I HAVE
MENTIONED ABOVE, in the order I have specified them.  Alonzo's notes will
give you a decent foundation regarding the architecture of the SATURN
processor and the instruction set.   Derek's notes will give you a good
foundation  in the object types and how the 48SX stores information
internally.  After reading these documents, I have been able to undertake
non-trivial ML projects. 

Another tool which you will find very valuable is Derek Nickel's Voyager
program.  Voyager is a tool for examining the code in the HP48's ROM.  It's
a great way to find those ML routines that the people at HP wrote to do all
those wonderful things like reading the keyboard, playing with the display,
and reading the hardware timer.

I hope that helps.

>>>Joe 

P.S. All of the documents mentioned above are available on Wayne's mail
server; a service that I highly recommend.