HEPAX/NoVRAM HOWTO?

[Egan Ford]

Hello all,

I'd like to get PPC into HEPAX. I have two 8192 byte ROM images. I have tried multiple attempts to get them on a diskette and read with READROM, but I get the following error: FL TYPE ERR

Using LIFUTIL I tried to force the TYPE to E070 (ROM41), but that did not seem to help.

How are others getting ROM images into HEPAX?

Thanks.

[Diego Diaz]

Hi Egan,

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.

Kind regards.

Diego.

Edited: 31 Aug 2008, 11:41 p.m.