11/70 ECC memory problems...

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1 total messages Started by Johnny Billquist Tue, 26 Jan 1993 17:45

#310

Author: Johnny Billquist
Date: Tue, 26 Jan 1993 17:45

29 lines
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I have an 11/70, with VAX-11/750 1Mb memory cards.
Before anyone points out that I can't have that, let me fill you
in on my stuff.
This machine was previously running at a school, where it worked fine.
The problem is that the memory box controller for the 11/70 only
clears the first 256Kbyte of each memory card. To get the 1Mb cards
to work, a little special extra card has been made, along with some
extra wrapping of the backplane.

Anyway, this memory *do* work, I know that.

My problem now is that since the controller don't zero all the memory,
the high 768Kbyte of each card contains random garbage. This includes
the ECC and parity bits.

The school which had the machine running had their own little code in the
boot program, which did a clear of the rest of the memory.
I could maybe get hold of that code, but that is a long shot, and
will take some time, so I'd like to get in touch with anyone who has
any experience in programming the MJ-11 memory box. I'd just like to
write zeros in the memory, and set the parity and ECC bits correct.
Anyone who has done this before?

	Johnny

Johnny Billquist                  || "I'm on a bus
CS student at Uppsala University  ||  on a psychedelic trip
email: bqt@minsk.docs.uu.se       ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol

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