|Re: HEPAX/NoVRAM HOWTO?|
Message #2 Posted by Diego Diaz on 31 Aug 2008, 8:42 p.m.,
in response to message #1 by Egan Ford
I assume you have written your PC files (.ROM images in DOS format) into a 3-1/2 floppy by using LIFUTILS. The file itself will be copied into your LIF diskette but, as you've already noticed, the file type is not suitable to be loaded into HEPAX RAM (nor any other HP-41 peripheral for that matter).
The reason is that the HEPAX command "READROM" needs a file with a different format.
.ROM DOS files writes every single HP-41 word (10 bits) into a couple of bytes (16 bits), wasting the remaining 6 bits of every even word. Back in the late eighties when every byte was valuable (and expensive) wasting memory or mass storage space was by no means acceptable.
Therefore, the required ROM image files format for HEPAX "READROM" to handle it appropriatedly is much more compact, using the exact amount of bits required to hold the ROM image: 5.120 bytes.
Apart from that there are some few mods that must be made in the DOS->LIF procedure when running LIFUTILS as HP-41 file format is somehow "weird" from LIF standards point of view.
Keep an eye on your mail inbox.
Edited: 31 Aug 2008, 11:41 p.m.