IBM ROM BASIC or lack thereof

From: Hans B Pufal <hansp_at_aconit.org>
Date: Thu Oct 4 00:15:10 2001

Sean 'Captain Napalm' Conner wrote:

> At the time the PC was first introduced, the clone manufactorers pretty
> much had to follow *what* the PC BIOS did, but in their case, they *didn't*
> have a BASIC to install in the BIOS. At the time, it probably made sense to
> say ``no ROM BASIC'' but really, nowadays, do even IBM PCs come with BASIC
> ROM? I think that in the abscence of ROM BASIC or some other internal program
> that loads, saying ``no bootable device'' is acceptable.


No that particular message is not accpectable. It would lead any
rational person to check that all disk devices are connected and
fucntional. A more correct message would be "No bootable media found"
Our BIOS can display a "Trying device xxx" message making the final
message even more useful since it is preceded by a list of devices which
were tried.


> If a user later adds a ROM with BASIC, it can follow the established
> guidelines to intercepting INT 18h with its own code.


Yes and no. In today's BIOS, INT 18 has bee "hijacked" or respecified to
be an integrated part of the boot sequence. It is actually called from
some bootstrap sectors to signal the fact that the media has no bootable
system.

Installing an option ROM with BASIC which redirects int 18 will probably
  cause all modern systems to fail any boot attempt and always enter
BASIC. Perhaps not such a bad thing ;-)

  -- HBP
Received on Thu Oct 04 2001 - 00:15:10 BST