regs41 - a filter to display an HP41 raw file as ’registers’
regs41 < Input file > Output file
The memory of an HP41 calculator is divided into 14 nybble (7 byte) registers. Many HP41 mass-storage files use an 8 byte record to store each register, with the nybbles in a scrambled order
regs41 undoes this scrambling and displays the 7 bytes of each register in hexadecimal, one register to each line of output. It is primarily designed as a tool for analysing unknown HP41 files. The HP41 data is read from standard input, and the hexadecimal dump of the registers is written to standard output.
The sdata manpage gives references to the format of the sdata file, which is the most common HP41 file made up of registers. The nybble scrambling is the same for all such files. Extend Your HP41 (W. A. C. Mier-Jedrzejowicz) contains a considerable amount of information as to how the HP41 packs data into registers
If disk1.dat is a LIF disk image containing some unknown type of HP41 data file called ST41 then
lifget -r disk1.dat ST41 | regs41
will display the data in that file as HP41 registers and will hopefully assist in understanding the format of the file
regs41 was written by Tony Duell, ard@p850ug1.demon.co.uk and has been placed under the GNU Public License version 2.0