PERQ T2 faults

Tony Duell ard at p850ug1.demon.co.uk
Fri Aug 17 17:10:17 CDT 2007


> 
> 
> Am I right in thinking that code 010 on the LED display is "hung at disk 
> boot"? If so, is there any way of getting a bit more detail as to the actual 
> error at this stage?

IIRC, 010 means the microcode ROM self-tests have completed, and the 
thing is waiting for a boot device.

Now, any PERQ will try to boot from the PERQlink (if you have an OIO card 
installed), then the floppy drive, then the hard drive. But certainly a 
T2 (or T4) will only boot from the floppy drive if the hard drive has 
gone ready.

> 
> This machine has a 5.25" ST-506/412 drive in it. I don't think it's the one 

What drive is it, and has the PERQ ever worked with this drive? Have you 
set the drive select jumpers correctly?

> with the dreaded sticking rubber problem; at any rate I've had it spinning up 
> on the bench - there seems to be a healthy clunk as heads unpark, and it 
> doesn't spin down, suggesting that side of things is healthy.
> 
> Other question: at the point when it's doing whatever checks yield the 010 
> code, should the display have initialised and be displaying anything? I'm

No. The video system is quite complciated to set up (rememebr there's no 
hardware text mode), it's not something that can be done by the 256-word 
microdoe ROM. The first screen output (assuming a normal OS) is the 
obvious patterns from the memory test routints in VFY (microcode loaded from
the boot drive), 
 
> getting nothing out of this system - but it's entirely possible that the 
> display init is further down the boot process, and so it's never getting that 
> far... (Anyone know which manual contains the pinouts for the video output and 
> landscape display?)

It's possible to decuce them from the motherboard ('MOM') schematics in 
the schematics book. The pinout is given in the hardware FAQ too.

What I would do is first check that the hard disk is going ready -- that 
is with a logic probe on the control connector with the drive cabled up 
to the PERQ.

If it was my machine (as I have the facilities), I'd trace the microcode. 
The low 12 microcode address lines (all you need for this) are brought 
out the bottom connector (26 pin) on the front of the CPU board, along 
wit hte microcode clock. A logic analyser connected there can trace the 
boot microcode. Then look at the source listings to see just what the CPU 
is doing.

If you don't have the boot ROM sources, ask me nicely for them :-)

-tony



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