20 Feb
2008
20 Feb
'08
1:28 p.m.
On Feb 20, 2008 1:05 PM, Tim Riker <Tim at rikers.org> wrote:
Someone else pointed out to me that there are ROM
images here:
http://www.bitsavers.org/bits/HP/1000_firmware/HP1000BootProms/
for some reason the roms only use the lower 4 bits of each byte. so each
word is in the lower half of four consecutive bytes in the ROM. I don't
see offhand how the IBL knows where to update slot information in the
ROMs. It also presumably needs to update address offsets as the code is
relocated? This part should be able to use relative addressing. Anyone
know how slot update works?
HP 1000 E-Series and F-Series
Computer Microprogramming
Reference Manual
http://www.bitsavers.org/pdf/hp/1000/2109-90004_1000EF_uPrgRef_Apr80
(.pdf extension missing on this file? rename as .pdf)
Appendix G, Page 8, INITIAL BINARY LOADER firmware listing.
From a quick scan of the comments it appears that the
IBL firmware
handler recognizes I/O instructions as it unpacks them from the loader
PROM and fixes them up on the fly if the select code is less than 10.
-Glen