Question about memory accesses

[MichaelW]

I had a good idea of what EA5BE000F030342F31302F393800FCD3 was, my focus was on the 2EFF26F5FF1BC000EA1DC000F000002B sequence and how it related to the description that sinsi posted. Clearly, it's not as simple as the BIOS being mapped to two addresses.

Michael, if i win the lottery, i am buying you a new machine – lol

Why wait, my self-esteem could use the boost now :lol

[dedndave]

your self-esteem should be just fine, Michael - lol
you write more good code on your old machine that a lot of guys do with newer ones
and - your code is tested on an older machine   :P

2EFF26F5FF  JMP Word Ptr CS:[FFF5]
1B C0 00

EA1DC000F0  JMP     F000:C01D
00 00 2B

the 3 bytes (twice) must be data of some sort
C01B seems a little low for BIOS

[FORTRANS]

Hi,

   Tried it on four machines.  Two (same brand) showed
the same lines.  Two showed different lines,  But all started
with:

Code Select Expand

EA5BE000F0

Regards,

Steve N.

[MichaelW]

I modified my code to display 35 bytes starting at absolute address FFFFC01B, and then using the same test system I got:

EB 06 BB 2A CC E9 61 07 2E 8E 06 65 C7 67 26 81
3D F1 FF 00 00 5B E0 74 05 EA 6C C7 00 F0 EA F0
FF 00 F0

And here is the disassembly done with Japheth's Debug clone:

Code Select Expand


-m6
-a c01b
0B04:C01B db EB 06 BB 2A CC E9 61 07 2E 8E 06 65 C7 67 26 81
0B04:C02B db 3D F1 FF 00 00 5B E0 74 05 EA 6C C7 00 F0 EA F0
0B04:C03B db FF 00 F0
0B04:C03E
-u c01b
0B04:C01B EB06              JMP     C023
0B04:C01D BB2ACC            MOV     BX,CC2A
0B04:C020 E96107            JMP     C784
0B04:C023 2E8E0665C7        MOV     ES,WORD PTR CS:[C765]
0B04:C028 6726813DF1FF0000
          5BE0              CMP     WORD PTR ES:[0000FFF1],E05B
0B04:C032 7405              JZ      C039
0B04:C034 EA6CC700F0        JMP     F000:C76C
0B04:C039 EAF0FF00F0        JMP     F000:FFF0


So at least one of the possible execution paths goes to F000:FFF0, and both paths reload CS, causing it to revert to the normal RM behavior and base address.

[Farabi]

I wonder if the thread starter could create a tiny PC whic only had a Monitor and external keyboard with 2 USB port and 1 MMC slot. I'd like to know how the price. This would be a good toys, no need a harddisk anymore. USB is enough.

[dedndave]

they have a number of embedded controllers out there that will run windows, Onan
you could probably get something going for around $200 US
google is your friend   :bg

[FORTRANS]

Hi,

   Iwas trying to refind a page on the OP's Geode LX processor
on AMD's site that had a nice looking "reference system" but
could not locate it.  A cute little box with nice features.

   Anyway, after browsing around I stumbled on Northec's site
and their products.  Two of interest (to me) were:

At only US$88.00, the MicroClient JrSX represents the least
expensive x86 compatible computer solution available.

The Gecko laptop is a small, energy efficient, rugged laptop.
The Gecko laptop will run virtually any x86 operating system,
including Windows and Linux.

   That laptop uses standard AA batteries and is inexpensive.
(And has some cute videos.)

Cheers,

Steve N.

[dedndave]

that is cute - lol
it would be nice to have at least one ISA expansion slot, though
hard to see how they make a profit on that laptop
the LCD screen, plastic moldings, and the BIOS code pretty much cover the $200 - lol

[Farabi]

$200 would be a good price. And also, a GSM card slot for cellphone.