[rescue] Sun2 update

[jwbirdsa at picarefy.com]

DaveM:
>On July 7, Walter Belgers wrote:
>> I've had to get an ECL monitor somewhere because I had no screen that I
>> could connect to the 2/50. Now I do have an ECL monitor and the 2/50
>> still works. It has a whopping 4Mb of memory.  I've been hinted at
>
>  That's quite a lot for a Sun2.  The biggest one I've ever seen had
>5MB.

   7M is the max. You can actually put in 8M, but the boot ROM sees that
last megabyte and thinks there's a video card or something like that. IIRC
it wouldn't even boot blindly.

>> The 2/170 has a video card but it's showing nothing on the screen. I
>> also attached a terminal to SIO-A. I do see the characters echoing, but
>> not always the correct character, so it's probably a serial setting
>> that's wrong. I haven't been able to find the correct serial settings
>> yet.
>> 
>> Does it make a difference in which slot a card is put?
>
>  Nope.  This is Multibus-I...straight-through bussing as far as I
>recall.

   Yes it does, for the same reason that it makes a difference in Sun's VME
chassis: the memory is on a separate bus which is not bussed all the way
straight through.
   On a 2/120, slots 1 through 6 are all connected together on P2. Normally
the CPU is in slot 1, memory is in 2 through 5, and slot 6 is either more
memory or the mono framebuffer. In older backplanes (501-1090), slots 6 was
even more special: if there wasn't a framebuffer, then a P2 terminator card
was required!
   Check out http://www.sunhelp.org/faq/sunref6.html for an annotated copy
of Sun's cardcage configuration matrix for the 2/120.

   Sorry if somebody has answered this already -- I can't really keep up
with the volume on the list, three days behind is as close as I've been for
a long time.

   --James B.