STPC Atlas primary bootloader and graphics

[md1]

Posted on February 11, 2003 at 11:54

STPC Atlas primary bootloader and graphics

[md1]

Posted on January 23, 2003 at 11:41

Hello,

I have written a bootloader based very much on ST's primary bootloader, except I am using the Elpin sytems free VGA bios, and locating it at C0000. My bootloader code starts at F0000, and when I make a far call to C000:0000 the VGA pops up with the sign on screen no problems.

However, when I shadow the F segment, I cant make any calls to the VGA bios, the system just freezes.

Any ideas?

[stephen239955_st]

Posted on January 31, 2003 at 12:18

As the primary loader copies itself in the shadow (F segment) before launching the secondary loader, now the primary loader does the following:

* set the secondary loader jumping address at C000:0003,

* share the C segment just before launching the secondary loader:

@GetStpc STPC_MISC1

or al, 00000001b ; share C segment

@SetStpc S, al

* confirm that the VGA BIOS correctly returns.

The VGA BIOS banner appeared and returned to the loader. Therefore there must be something missing.

Remark: This was used on an STPC Atlas because we didn't need to install interrupt A1h. If it's not an Atlas, you need to install one before calling the VGA BIOS.

Attached are the updated source code (see '';;SD'') and the binary image (loader + VGA BIOS). To compare with what you did.

________________

Attachments :

ldr.zip : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006Htu0&d=%2Fa%2F0X0000000aYY%2Fq1I9H_iHceyuCy7cwjl3noREGbnmz92qCkXARPQmaFU&asPdf=false

[md1]

Posted on February 11, 2003 at 11:54

Thanks for you reply Stephen. I had made a code error which had caused an incorrect value to be written to the shadow configuration register. This actually works fine now.

Thanks for your reply.

Best Regards,

Martin.