n233dk@tamuts.tamu.edu (Rick Grevelle) (09/12/90)
Thanks to J"urgen Koslowski for pointing out an error in the create MACF
routine. However, the fix offered isn't quite right. The one below is.
CMACF [4152]
%%HP: T(3)A(D)F(.);
\<<
# 3174197160731741h
# 181314E331741607h
# 4173170EC6A830F8h
# C808461241731705h
^^^ digits transposed, ought to read 731!
1 3 START
# 5193h SYSEVAL
NEXT #2DCCh
# 5A03h SYSEVAL
# 5ACCh SYSEVAL
\>>
In regards to your question concerning the instruction DA; it is a MOVE,
register to register, and is explained in the Processor Notes as follows:
-------------------------------------------------------------------------
MOVE Register to Register
ppz MOVE.f s,d
pp | f z | s d
-------- ---------
A8 | P 4 | B A
A9 | WP 5 | C B
AA | XS 6 | A C
AB | X 7 | C D
AC | S 8 | A B
AD | M 9 | B C
AE | B A | C A
AF | W B | D C
D | A
Examples:
D9 MOVE.A B,C ; C gets B (20 bits)
AE4 MOVE.B B,A ; A gets B (8 bits)
AFB MOVE.W D,C ; C gets D (64 bits)
DA MOVE.A C,A ; A gets C (20 bits)
>Another suggestion concerning this program: It seems to me that the
>new HP48 instruction NEWOB can be used to replace "" +, saving 2.5 bytes.
In an effort to keep routines such as these short, it becomes necessary to
use a bit of trickery. STRING->CODE uses a combination of two tricks; one
used by Alonzo in his PEEK scheme, and another one that I discovered. The
point here is that NEWOB will indeed work and save 2.5 bytes in doing so.
However, neither of the two are particularly efficient. They are merely a
convenient manner in which to compensate for the forementioned lazy trickery.
It should be mentioned that HP does not use trickery of this sorts. Thanks
to a variable length PEEK routine written for the 28, I was able to isolate
and disassemble the routines responsible for updating low RAM when new objects
are created.
A more recent example of how this is done in the 48 can be found in the ->ASC
and ASC-> routines recently posted by Dr. Wickes. The details involved here
are numerous, and time required to understand them would be great. Now that
school is back in full swing, I have no such luxury!
Rick Grevelle