Re: Apple IIe boot question

[dempson@actrix.gen.nz (David Empson)]

Bill Garber <willy46pa@comcast.net> wrote:

> Won't an Apple lower than a IIe enhanced boot from
> anything but a 5.25 drive?

A ][+ or unenhanced IIe will only automatically boot from a 5.25"
controller card, or from another interface card which has the same ID
bytes.  (You can manually boot from other disk controllers using PR#n -
if necessary, press Control-Reset to get to the BASIC prompt first.)

The ID bytes checked by the ][+ and unenhanced IIe are at $Cn01, $Cn03,
$Cn05 and $Cn07.  They must contain the values $20, $00, $03 and $3C, or
the autostart firmware will not recognise the card as bootable.

Disk controller cards which support the SmartPort firmware interface
(including the Liron card, SuperDrive card, standard slot memory
expansion cards and Apple SCSI cards) contain the value $00 in location
$Cn07, so they won't boot automatically in a ][+ or unenhanced IIe.

In the enhanced IIe and IIgs (and the IIc in principle), the autostart
firmware only checks the first three ID bytes, allowing SmartPort
interface cards to boot.

-- 
David Empson
dempson@actrix.gen.nz