Custom ROMs for HP Portable PLus

[pamphonica]

I've searched but cannot find a detailed write-up for making custom ROMs. There is a lot of good information scattered about in this forum. Did Martin H do a write-up at some point?

There is basic documentation and the essential tools here in the Tools and Documentation section. Thanks Jeff!

But I am still a little unclear about putting software into a ROM. I think it goes something like:

1. get EDISK, IMAGE and possibly BURN utilities (on Disk or ROM from Jeff's page)
2. make a suitable size (128K or 64K) EDISK (matching the 27C512 eprom size) and format it
3. put required files in that directory
4. use IMAGE to make an image file
5. use MARK, FENCE, CHECKSUM to make boot sector etc
5. use SAVE to produce an output file (.HAF for half-bank) or files (.EVN and .ODD for full-bank) ROM
6. burn ROM(s)
Is that about right?

I'm still working out the exact command line switches to use with EDISK and IMAGE.

Martin Hepperle suggests:
" A 64KB EPROM (27C512) is possible without problems.
You would configure a half bank with EDISK.SYS /2 /H
to create a .HAF file with 63488 bytes on ram drive"

But the documentation is confusing.
/2 allocates 128K of system RAM (128K bytes presumably)
/H allocates two halfbank drives of 128Kb (Kbits presumably)
I want to blow one 64K ROM (27C512)

Any illumination on this would be appreciated.