HP 41: Creating EPROM Images

[Michael Fehlhammer]

Vintage EPROM devices ( like HHP portable EPROM, ERAMCO EPROM box etc. ) use standard EPROM chips and spread the 10-bit words of HP-41 mcode over two chips.
The usual distribution is: one EPROM chip holds the lower 8 bits of all words (mostly called L8), and the other one holds the two most significant bits (U2), in a packed format (4x U2 in one byte).
For example an HHP Portable EPROM in 32k (8 pages) configuration holds 8 times 4k byte (L8) in one 27256-type EPROM (256 kbit), and 8 times 4k x 2bit in one 2764-type EPROM (64kbit).

Now I'd like to burn my own selection of ROM images onto my HHP EPROM device.

For that I need a program that creates these two files (L8 and U2) from a standard HP-41 ROM image ( 16 bit, 6 leading zeroes); since I am pretty sure that such a tool already exists and it's stupid to reinvent the wheel, I hope that some HP-41 expert could give me hint where to find the conversion utility.