Which Dec Emulation is the MOST useful and Versatile?

js at cimmeri.com js at cimmeri.com
Mon Oct 30 14:50:24 CDT 2017

On 10/30/2017 2:42 PM, Chuck Guzis via 
cctalk wrote:
> Well, "emulate" is a very fuzzy word, even in the context that you provide.
> Taking as an example, some pre-S/360 hardware that's easily verified, is
> the IBM 7094.   It ran the instruction set of the 7090 but with a single
> departure--the use of 7 index registers, selectable using a 3-bit
> isntruction field.  In the 7090, that same field selected any of three
> registers--if you selected more than one, the contents were ORed
> together before subtracting from the base address.   The 7094 did have a
> "7090 compatibility mode" that used only the first three index registers
> in the same manner as the 7090.
> Specific hardware than enabled one machine to act as another.
> So, is that "7090 emulation" on a 7094?
> --Chuck

In the sense that the 7094 can emulate 
(regular English usage) a 7090, then yes 
it is.

- J.

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