Subject: IIsi vertical stripes
To: MacBSD General <>
From: David Leonard <>
List: macbsd-general
Date: 10/20/1994 10:43:19
Hello hackers!

I've been fiddling with netbsd/mac68k on this IIsi on and off for a while now;
I wish I had the time to do more on it; I especially wish I could get into
understanding the booting mechanism a lot more.

Only one kernel has ever worked for me and that is the kernel.
Every other kernel (including up to a 1.0 sent to me by Alan "cool dood" Briggs)
just draws vertical stripes up the screen and hangs before any grey bars are
drawn. (Very early kernels just hung but the rest of 'em stripe)

When I say stripe, it looks like a regular pattern (maybe about 100 bits wide)
is being written to the screen. It fills from the bottom up. Actually watching
carefully, the "[preserving" line gets drawn, then from the bottom row of
pixels of this line, you get a short mess of bits, then a pattern fills this
(12 pixel high?) line of text in an upward direction, then the rest of the 
screen from the very bottom of the screen is filled with the regular pattern.
It is regular in that you get the effect of thin vertical black stripes running
up a predominately white background.

Unluckily I can't screen dump or break into macsbug at this stage so the
above is the best description I can come up with.

I understand that it was Lawrence K who got the 073194 kernel to work on a
IIsi (yay lk!) and was wondering if the changes that he made to get it to work
were then lost before the next kernel release etc.

Initially I believed that errors in file transfer caused the stripes, but I
was wrong. Being very careful and even checking with od to see that there are
both CRs and LFs in the kernels has eliminated the un-'gzip'ping in ascii mode
problem i thought i had had. The newer kernels just draw stripes and hang.
I am able to see a "[ preserving <some number> bytes of netbsd ]" message
or similar across the top line just before this happens.

In addition, (and another IIsi'er I have talked to has not had this problem)
the functional kernel functions great even fantastically for a short while
until you start to do something involving a bit of extensive memory access
and it then MMU panics unpredictably. With some help from alan I even got
a small a.out that continuously mallocs and fills a pattern into memory that
panics after a couple of megs are consumed. Hopefully this is not tied into
update kicking in which I havent attempted to observe simultaneously.

As I said, not everyone with IIsi's is experiencing this particular MMU

For the record:
IIsi 17M scsi0=1G scsi2=80M 13"RGB Nubus-FPU - all apple h/w (except the 1G).
no {scanner, printer, tapedrive, PDS cards or other extensions}.

The other IIsi guy (who's name I forget now - but I think is in
has a PDS FPU and I have a NuBus FPU - He had 5M of memory and I have 17. This
is yet another confounding factor.

Please lk, if you are out there, what magic did you incant to get my 'si to
enjoy the benefits of Alice BSD?

Dave Leonard
David Leonard                
The University of Newcastle            4th year Engineering/CompSci student