Path: utzoo!mnetor!uunet!mcvax!jurjen
From: jurjen@cwi.nl (Jurjen N.E. Bos)
Newsgroups: comp.sys.hp
Subject: HP28C (version 1BB) SYSEVALs
Message-ID: <7509@boring.cwi.nl>
Date: 22 Feb 88 21:52:28 GMT
Organization: CWI, Amsterdam
Lines: 135
Keywords: HP28C, SYSEVAL


Introduction
Warning: people not having version 1BB can get disastous results.
The HP28 objects consists of a routine pointer, followed by the
data field.
The HP28C is adressed in nibbles.
Pointers are, as you will know, 5 nibbles.
The routine pointer points directly to a machinecode subroutine that
executes the code for that kind of object.
The data field of an object can be anything.


Types, as far as I know:
Pointer	Type	Followed by (size in parentheses)

02911	pointer	value(5)
02933	real	sign(1),mantissa(12),exponent+500(3)
02955	high r.	sign(1),mantissa(15),exponent+50000(5)
02977	complex	real,imag part (2*16)
0299D	high c.	real,imag part (2*21)
029BF	byte	value(2)
029E1	?
02A0A	array	size(5),type(5),#dim(5),dimensions(5)...,data
02A2C	?
02A4E	string	size(5),data(2)...
02A70	binary	size(5),data(1)...
02A96	list	data(5)...,02F90
02AB8	?
02ADA	algebr.	data(5)...,02F90
02C67	program 27F0A,data(5)...,27F1F,02F90
02C96	code	size(5),...
02D12	name	#letters(2),data(2)...
02D37	local n. #letters(2),data(2)...
02D5C	function number(2*3)
067A1	true
067E0	false


Interesting addresses: (routines use pointer arguments, and don't
check anything!)
0201E	DEPTH
0205A	DUP
0207E	DUP2
020AB	DUPN
020F5	SWAP
02116	DROP
0212A	DROP2
02140	DROPN
02067	ROT
02094	OVER
020B4	PICK
020F7	ROLL
02241	ROLLD
03495	CDR  (really!)
034DC	+ for strings
03422	convert string to byte
03599	+ for lists
O369D	+ string+byte
0372B	make structure given type and size
03845	->PROG
03859	->LIST
0386D	->ALG ebraic
0389B	STRUCT->
067FA	XOR
06812	NOT
0684E	== for reals
06866	AND
06895	OR
068B7	== for any object
06982	get type
069C4	000000h =
069E5	000000h !=
06A02	<
06A37	== for pointers
06A6C	!= for pointers
06AA1	>
06ADA	+
06AFE	-
06B0D	1+
06B2C	1-
06B4B	2+
06B6C	2-
06B8D	2*
06BAC	2/
06BCF	*
06C04	DIVMOD


06C98-06F04 are pointer constants of all kinds of values.
177F1-1BF4C are the routine for the user commands;
they check stack depth, do LAST and call an internal routine.

1C490	number->pointer
1C565	pointer->number
1C952	bool to number
1EA55	number to bool

Interesting programs:

Instead of <n> SYSEVAL one can put the pointer to n directly in the program
code, as will be shown later. I write <n>h if I mean either <n> SYSEVAL or
the repolacement.

SYS without EVAL (very nice for peeking in the ROM):

SYS
<< 06D6Ah 32F25h >>

READ
<< 10 - HEX
  4 1 FOR R
    "" 1 4 START
      OVER 06D6Ah 32F25h 04358h 1C565h R->B
      #100000 + ->STR
      DUP SIZE DUP 4 - SWAP SUB
      " " + SWAP +
      SWAP 5 + SWAP
    NEXT 1 23 SUB R DISP
  -1 STEP 10 + >>

SS
<< DEPTH ->LIST 'T' STO 4FFABh
  READ DROP T LIST-> DROP
  'T' PURGE >>

->PRG Convert contents of stack to program. You don't get << and >>,
but they're unnecessary anyway.
<< 0201Eh 03845h >>


I hope this is clear; please mail me any special requests;
I'll post the answers, if it isn't too much.

Enjoy the internals of your machine! Jurjen
No I'm NOT a saint!