Re: HP41 ROMs Message #3 Posted by Tony Duell on 5 Apr 2004, 2:05 p.m., in response to message #2 by Artur
It should be possible. What you need to do first is work out how the 10 bit HP41 words are packed into bytes of the file. Sometimes the file lenght gives a clue here. If it's 8192 bytes for each 4K ROM block then it's almost certainly 2 bytes for each word (8 bits in one byte, 2 bits in the other, and a look with a hex editor will tell you which way round they are!). If it's 5120 bytes for each 4K block, then it's probably packed 4 words into 5 bytes (4 bytes containing the low 8 bits of each word, 1 byte containing the 4 2-bit high bit fields). The latter is more common in my experience, and I've got a program (C, for linux) to extract the data from the files saved by the Eramco MLDL-OS system.
When you've got the data out, you then probably need to split it into high and low bytes, and repack the high bytes (of which only the 2 LSBs are significant) into the format your EPROM box expects (this may well be packing 4 of 2-bit fields into a byte). Then send to an EPROM programmer (may have to convert to Intel-hex first, it depends on your programmer) and burn the EPROMs.
I've done it from files on an HP41 LIF-format disk, but I have no idea if the .ROM files you're talking about are the same format.
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