🚀 go-pugleaf

In article <428@quando.UUCP> wichert@quando.UUCP (Peter Wichert) writes:
>
>Last time I tried to set up my own little small 'kernel' to see
>how my own vbl's and hbl's work. Therefore I have a hardware initialisation-
>procedure, similar to the BIOS procedure. But something unexpected happens:
>After the init is done, a thin bright vertical stripe  at the left border
>of the screen appears. This stripe is much brighter than the normal white
>of the screen. Does anyone know about this ??? I don't.
>
>
>				Bye, Peter

Humm, looks like no horizontal scans are done (I'm not quite sure how to say
this in English; it seems the voltage for horizontal bending the beam is
constant). Are you sure that the IPL mask in the status word is set correctly?
I know that the standard HBL does something like:

        move.w   sr,d0
        and.w    #$700,d0  * test the 3 IPL bits.
        bne.s    nochange  * if not zero
        or.w     #$300,sr  * could be wrong; don't know if this is valid
nochange
        rte

The ipl bits are available on pins of the MC68000; these probably are used
to communicate with peripherals (interrupt control lines). It could be that
your HBL is not run, or that it does not set the interrupt control lines
correctly (using the status word). Maybe you could supply some more info
(could be mail) ?

       Leo.