1 Nov
2010
1 Nov
'10
7:21 a.m.
Date: Sun, 31 Oct 2010 17:39:14 -0700
From: jws at jwsss.com
To:
Subject: Re: Repairing core memories....
Microdata core stacks had these huge resistors in the inhibit circuit
that would literally set the board and system on fire.
Panel mode, R register 0xA010 in the switchers (write) and run, wait for
smoke or PS failure.
Microcoded machines with easy access to this sort of 1/2 cycle write
would hit the board every 200us, when the requirement was for 600us for
a 1/2 cycle read, and 1000us for a Write. The writes would not complete
that fast, but the 1600 (and 800's) logic was such that you would cycle
the board fast enough to cause the damage.
Hi
YOu mean ns, not us. 1000us is one millisecond. That is not
too fast.
I wonder what the failure mode is. It would almost have to be
that the cores cracked from thermal stress. I can't imagine
the magnetic properties changing otherwise.
A tiny air gap would make the cores hard to magnetize.
Dwight