DG MVs (was RE: microcoding a PC into a PDP-11 (was: RE: Classic Computers

From: Derek Peschel <dpeschel_at_eskimo.com>
Date: Mon Sep 24 18:42:26 2001

On Mon, Sep 24, 2001 at 11:56:30AM -0700, Chris Kennedy wrote:

> Faced with the issue of _how_ to read the microcode the MV designers
> did something modestly clever. Since the MV is an almost-proper superset
> of the Nova, and since the Nova ISA was well understood, when a MV first
> powers up it thinks it's a slightly brain damaged Nova 800 (there's no
> page zero auto inc/auto dec instructions and most "do nothing" I/O an
> skip instructions are not honored), which gave them a reasonably
> complex abstraction upon which to open and traverse file systems
> looking for the MV microcode...

But where is the microcode for the brain-damaged Nova 800 instruction set
stored, and can it be overwritten?

-- Derek
Received on Mon Sep 24 2001 - 18:42:26 BST