WIN XP and DOS Emulation

[MooseFET]

This supports my contention that most BIOS's setup the machine to look
like a basic PC (actually about AT class) before trying to boot the
machine from disk.

Many BIOS's such as the one I'm using right now work more like the PC
XT to get the boot done. It uses the "game cartridge" detection by
searching for IIRC A5A5(IIRC)[1] at the start of a memory page. It
finds the PROM of the video card to get the video started and
strangely enough part of the very same PROM that is doing the
searching to get the first version of the disk operations going.  

[1] It was about a year ago that I looked it is a pattern like that.

The first version of the disk code is just smart enough to load the
master boot record that then gets GRUB started. Only after GRUB has
started the OS is the whole disk seen. During booting, it is confined
to the first 1024 tracks because the BIOS code uses a 10 bit value for
the track.

 

[Tim Williams]

My XT machine supports external ROMs. The documentation (which I finally
found online, and is quite well specified) states:

-=-=-

The ROS checks for external ROMs between addresses C0000 and F4000 in 800h
(2k) byte increments. An external ROM which conforms to the following
specification will be initialised by the ROS:

1. The first two bytes contain the hexadecimal value 55AA.
2. The next two bytes contain the size in 512 (1/2K) byte increments.
3. The next byte is the initialization routine entry point.
4. The LS byte of the byte sum of the ROM is zero.

When a ROM conforming to this specification is located then the
initialization entry is called.

If the checksum test fails then an error message is displayed and
initialization is not called.

The IGA BIOS ROM conforms to above standard and if it is enabled, it is
entered (at C0000)...

-=-=-

So the ROS (Resident Operating System, i.e. the BIOS startup code)
initializes whatever's found (which, in my case, includes the hard drive
controller's BIOS and the IGA (Internal Graphics Adapter, which is high
resolution EGA with a whopping 256k RAM)). I could, in principle, burn an
EPROM that conforms to these specifications and run my own programs
instantly on startup.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

This supports my contention that most BIOS's setup the machine to look
like a basic PC (actually about AT class) before trying to boot the
machine from disk.

Many BIOS's such as the one I'm using right now work more like the PC
XT to get the boot done. It uses the "game cartridge" detection by
searching for IIRC A5A5(IIRC)[1] at the start of a memory page. It
finds the PROM of the video card to get the video started and
strangely enough part of the very same PROM that is doing the
searching to get the first version of the disk operations going.

[1] It was about a year ago that I looked it is a pattern like that.

 

[[email protected]]

What is the trick to getting my old DOS programs to run under WIN XP?
Some work some don't. For example with WIN98 I could run all DOS
programs very well including some radio programming software that
although the serial interface was too fast to read/write a radio, I
could edit codeplugs with the "UBer" computer and use my slow 486 to
program the radios.

Now these same programs don't seem to do anything except open a dos window.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money"  ;-P

http://en.wikipedia.org/wiki/OpenDOS
I tri-boot (windows, linux and open dos). If you use a program that
depends on a fast interupt response, you probably have to run open
dos.

I am going to give that dosemu program a try. My understanding is with
linux you can get a fast response to interrupts IF you own the port.
That means either running a root or chowning the device. [No first
hand experience here, just what I read.]

 

[JosephKK]

My XT machine supports external ROMs. The documentation (which I finally
found online, and is quite well specified) states:

-=-=-

The ROS checks for external ROMs between addresses C0000 and F4000 in 800h
(2k) byte increments. An external ROM which conforms to the following
specification will be initialised by the ROS:

1. The first two bytes contain the hexadecimal value 55AA.
2. The next two bytes contain the size in 512 (1/2K) byte increments.
3. The next byte is the initialization routine entry point.
4. The LS byte of the byte sum of the ROM is zero.

When a ROM conforming to this specification is located then the
initialization entry is called.

If the checksum test fails then an error message is displayed and
initialization is not called.

The IGA BIOS ROM conforms to above standard and if it is enabled, it is
entered (at C0000)...

-=-=-

So the ROS (Resident Operating System, i.e. the BIOS startup code)
initializes whatever's found (which, in my case, includes the hard drive
controller's BIOS and the IGA (Internal Graphics Adapter, which is high
resolution EGA with a whopping 256k RAM)). I could, in principle, burn an
EPROM that conforms to these specifications and run my own programs
instantly on startup.

Tim

Or save yourself a lot of hassle and buy an ASUS mobo. Oh wait, it
just boots to linux and you may not want that.

 

[Tim Williams]

Or save yourself a lot of hassle and buy an ASUS mobo. Oh wait, it
just boots to linux and you may not want that.

ASUS makes XT mobos that boot to linux? Cuz that's what I thought we were
talking about. ;-)

Tim

 

[JosephKK]

ASUS makes XT mobos that boot to linux? Cuz that's what I thought we were
talking about. ;-)

Tim

I think so. See this also:
http://usa.asus.com/search.aspx?searchitem=1&searchkey=linux

have fun.

 

[Tim Williams]

I think so. See this also:
http://usa.asus.com/search.aspx?searchitem=1&searchkey=linux

have fun.

Doesn't look XT to me.

Tim

 

[JosephKK]

Doesn't look XT to me.

Tim

If they had been in the business back then, it would have to load it
from hard disk. I had my i teeth crossed.