30 Mar
2018
30 Mar
'18
10:31 a.m.
On Thu, 29 Mar 2018, Peter Coghlan via cctalk wrote:
It looks like position 0 (J8) is the normal operating
position for the jumper
then and I did not move mine previously. With the jumper in this position,
I get some mini console output on power up but I do not get an SROM> prompt
and I cannot enter mini console commands unless a machine check happens or I
force an error by removing a memory riser or doing something else to cause
an error.
I thought you'd get the SROM firmware to halt and wait for a command
after POST if J8 was removed and none of the other positions shorted.
Have you tried running with all positions open?
(I do not get anything on the MMJ console port under
any cirumstances.)
SROM code runs from the processor's cache and it's too small for fancy
stuff like getting through to the regular Zilog serial ports, which are
far down on an I/O ASIC bus and require a lot of mainboard hardware to
initialise before they can be accessed. It's also meant to work in system
bringup or in the presence of problems with system components, so the
fewer pieces of logic it relies on the better.
It's only main firmware that initialises the regular console.
Maciej