Peter's Notes on the HP Calculators

Software for the HP48

A huge repository of hp48 software is here and the program descriptions are here.

Connecting Linux to my HP48-SX

Wanted to upload a QR Decomposition routine to my HP48-SX. Here's what I did after hooking up my HP calculator to the computer using the serial cable:

# aptitude install gkermit ckermit
$ kermit
(/home/p/foo/) C-Kermit>SET MODEM TYPE DIRECT
(/home/p/foo/) C-Kermit>set line /dev/ttyS0
(/home/p/foo/) C-Kermit>SET SPEED 9600     
/dev/ttyS0, 9600 bps
(/home/p/foo/) C-Kermit>SET CARRIER-WATCH OFF
(/home/p/foo/) C-Kermit>SET FLOW NONE
(/home/p/foo/) C-Kermit>SET PARITY NONE

I pressed I/O | RECV on the calculator. Then:

(/home/p/foo/) C-Kermit>send GAUSSELM.SRC

And, good Thor almighty, it appears to have worked! Holy Cow!!! Damn, I love Linux.

The Gauss Program

I pressed VAR and saw a directory named GAUS. I entered the directory and saw the variables QR, LU, DCMP, RCMP, and SWRW. I entered the matrix A:

[ [3,-6], [4,-8], [0,1] ]

and pressed QR. The first item on the stack became:

[ [5,-10], [0,1] ]

which is the R matrix, and:

[ [.6,0], [.8,0], [0,1] ]

in stack position 2, which is the reduced Q matrix. I pressed * to multiply Q and R, and lo and behold, I got A back. w00t!


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