30 Jul
2012
30 Jul
'12
11:41 p.m.
On Mon, Jul 30, 2012 at 8:48 PM, Camiel Vanderhoeven
<iamcamiel at gmail.com> wrote:
Hi Again,
While I'm still struggling with the powers supply in the /84, I
decided to also take a good look at the /05. Amazingly, the power
supplies on this one (1972) are 13 years older than those on the /84
(1985), yet their outputs look absolutely perfect. Plugged in the
cards, and it seems to work, apart from one annoying little thing: one
of the front panel switches is bad. I noticed it when I was
depositing, then reading back some data, then took a multimeter to
determine that it's the switch itself that's broken. Cosmetically it
looks ok, but it doesn't work. It's just one of the address/data
switches, all other switches work fine. Are there any replacements for
these switches to be found?
Camiel.
The part number on these switches is "AIRPAX 028-317-0001", What's
special about them - I guess - is the mounting plate on the top. It
snaps into the metal rails that keep all the switches aligned, and
it's got two holes which the plastic switch cover snaps into. I
couldn't find anything similar in the C&K catalog.
I've also tries cleaning it, but no luck yet.
For now, I've replaced the failing switch with the HALT/ENABLE switch,
and replaced that one with a standard C&K switch. It doesn't look
pretty, but at least it'll work.
Now the next thing is to connect a serial console to the CPU. Read up
a bit on this, and I'll need to put a MAX232 behind the TTL outputs.
Also, the little switch was set to the "1" position, which means
either 110 or 150 baud. I turned the switch to the "5" position, which
should get me 2400 baud.Time to find out - and check the cpu a bit
further in the process. I toggled in a simple program that sends a
"10101010" bit pattern to the serial port. Hooked up my scope to the
TTL output, and adjusted the potentiometer until I got the bit-period
to 417 usec. I'm now starting the search for a MAX232.
Camiel.