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HP Forum Archive 17

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9825 assembler/ROM programming
Message #1 Posted by Bohemia House on 14 Aug 2007, 12:03 p.m.

Does somebody know how to program, to develop a new ROM for HP 9825 ???

      
Re: 9825 assembler/ROM programming
Message #2 Posted by Eric Smith on 14 Aug 2007, 1:19 p.m.,
in response to message #1 by Bohemia House

I don't recall there being an supported assembly development system for the 9825. It uses the same processor as the 9835 and 9845, so you could use the assembler ROM for those. However, the language interpreter on the 9825 is much different, so you'd have to figure out how to interact with it. US patents 4,075,679 and 4,437,156 might be helpful.

            
Re: 9825 assembler/ROM programming
Message #3 Posted by Klaus on 15 Aug 2007, 2:23 a.m.,
in response to message #2 by Eric Smith

The relative addressing of the 9825 is different from the 9835/45. You will find in the patent of the 9825 two modes of relative addressing selected by the CPU pin RELA. To quote one of the developers of the 9825:

Quote:
to answer your first question regarding the function of RELA, it's a hardware selection used to determine Absolute vs Relative addressing mode calculation, tied low in the hp9825 to accomodate code destined for rom's (allows access to any word within a page), the pin is tied high in hp9835/45 to accomodate relocatable code segments.

And to be quoted further:

Quote:
there is a binary that i wrote for the 9825 that implements a bpc assembler and reverse assembler that proved to be very useful at the time, also, after meeting up with steve i put some work into creating a macro package for TeX that aims to implement a modern assembler for the bpc source so that the listing files (that i have in paper form) can be reproduced

After a discussion about the 9825 on this forum, this developer contacted me and answered many of my quesions. I think these details will eventually show up on hp9825.com. There is a useful simulator of the 9825 available from one of our forum members.

                  
Re: 9825 assembler/ROM programming
Message #4 Posted by Eric Smith on 16 Aug 2007, 1:03 a.m.,
in response to message #3 by Klaus

Quote:
The relative addressing of the 9825 is different from the 9835/45.

IIRC, the 9825 does not have relative addressing, but rather uses the BPC in page addressing mode similar to the 21xx and 98x0.

Quote:
There is a useful simulator of the 9825 available from one of our forum members.

I must have missed the announcement? I've only seen Achim's hp9800e, which (AFAIK) doesn't simulate the 9825.

                        
Re: 9825 assembler/ROM programming
Message #5 Posted by Klaus on 16 Aug 2007, 2:33 a.m.,
in response to message #4 by Eric Smith

Quote:
IIRC, the 9825 does not have relative addressing, but rather uses the BPC in page addressing mode similar to the 21xx and 98x0.
I think the patent mentions 2 modes of "relative" addressing (depending on the RELA-Signal), so I count that as "relative" addressing. Anyway, the addressing mode of the 9825 differs from the 9835/45, so I don't think you can use the Assembler ROM of the 9835 to create new commands.

And yes, I meant Achim's hp9800e, as far as I know, simulating the 9825 is on the TODO-list.

Edited: 16 Aug 2007, 2:33 a.m.


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