Well last night I fired it back up and now everything works! Even boots
from 0030.
So the next question concerns running DECX8 off the diag pack. I do a ".R
DECX8" and it halts @ 0x200, fine. I enter 0040 to the switch register and
hit run. I don't get a message as the DECX8 document promises. It halts
again @210 and I enter 0030, run, still no output and it halts @ 2001 (or
was it 2100?).
Anything I'm doing wrong here?
Thanks,
Marc
On Thu, Jan 23, 2014 at 8:45 AM, Marc Howard <cramcram at gmail.com> wrote:
One step forward, two steps back...
I got a few minutes to test last night and now I can't even boot the RK05
from 5000, let alone 0030.
No data is being xfered. Something flaky here. What a shock that 40 year
old hardware has intermittent problems.
I think I'm going to pull the TC08 interface cards (M8350/60) just to rule
out interference. Then I'll crank up the logic analyzer. Luckily I have
an extender card that has 68 of the more interesting omnibus signals
hard-wired to analyzer pods. Debugging the disk interface itself would be
a nightmare due to it's multi-board stackup.
Marc
On Wed, Jan 22, 2014 at 7:44 PM, Toby Thain <toby at telegraphics.com.au>wrote:
On 22/01/14 10:23 PM, Rob Doyle wrote:
...
The RK8E bootstrap is a little strange....
The bootstrap program /assumes/ that the disk is faster than the CPU.
When I sped up my PDP8, I exposed this race condition.
If the code is still executing the instruction at address 0031 after the
disk read operation, the disk wasn't read...
Thanks for sharing that little bit of knowledge. Awesome.
--Toby
Rob.