>On early IBM machines, ROM Basic was entered by performing an INT
>18h instruction. On machines not implementeing ROM Basic, calling
>int 18 would simply display the "no rom basic" message, often in 40
>col mode since that was the lowest resolution suupported.
>
>Many bootstraps terminate with a call on Int 18 to indicate the absence
>of bootable code on the media hence the message would appear.
It's been a while since I powered one up, but since the IBM
PCjr's BASIC ROM is on a cartridge vice on the mainboard, what do you
get if you boot the machine with neither a DOS floppy or the
cartridge BASIC inserted? Were there other IBM PC's that didn't have
the BASIC ROM on the mainboard?
Jeff
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Received on Sun Sep 30 2001 - 12:19:48 BST