> Does it matter very much? There's at least 64K bytes for the BIOS ROM and
> often twice that or more. Besides, that's why I suggested a SIMM or DIMM.
> What I had in mind was a bootstrap in the "BIOS" ROM socket and an EPROM
> or two on a home-made SIMM/DIMM with the main code.
Cool idea -- flash on a DIMM. Has anyone ever heard of such a beast?
Have you ever soldered down a flash ROM? Not fun. I used 36 gauge self-strip
magnet wire and tweezers under a 40X stereoscope. I'd rather buy one
prebuilt if available. If you build you own, it might be hard getting the
interfacing and timing compatible with DRAMs.
Of course it would be feasible to implement a PDP-11 emulator in the BIOS
ROM, it just would not be as fast as the one I'm thinking of. Back in the
days of QEMM/386, I remember allocating 64K for the BIOS ROM. I haven't
really looked that closely at a BIOS ROM since then. I was wondering if
modern mainboards had larger ROMs, or if they still are stuck with 64K. You
could compress the emulator into the ROM and expand it to RAM at boot time.
Since the emulator will be pretty regular, it might compress well.
Another idea: if you created the emulator with a code generator, you could
put the code generator into the boot ROM, and compile the emulator at boot
time.
I haven't looked at it yet, but I was imagining the emulator would be a
several megabytes of code.
--
Jonathan Engdahl???????????????? Rockwell Automation
Principal Research Engineer????? 24800 Tungsten Road
Advanced Technology????????????? Euclid, OH 44117, USA
Euclid Labs????????????????????? engdahl_at_cle.ab.com 216-266-6409
Received on Mon Sep 17 2001 - 08:42:03 BST