[Simh] Rainbow100

[Timothe Litt]

On 19-Jul-17 23:23, Bill Cunningham wrote:
>     There's no simulator for DEC's first micro is there? Will there
> ever be one?
>  
> Bill
>  
>
That wouldn't be the Rainbow.

There was the Harris/Intersil pdp-8 on a chip c.a 1975. 

The DEC/WD LSI11 c.a. 1976 followed.

All these were in embedded systems.  The LSI-11 (and especially its
follow-ons, the T/F/J11) were used in a number of DEC's storage and
communications controllers, until ultimately replaced by VAXes.  (Yes,
your VAX probably had more VAXes in the IO subsystem than you knew
about.)  They were also very popular for third party embedded systems -
from volume copiers to airport landing lights. 

If by 'micro', you mean general purpose consumer packaged Intel
architecture machine, that would be the Robin (VT180), which is a Z80
CPU with dual 5 1/4 inch floppies, as a plugin board for the VT100. 
CP/M.  Produced in the AD group, which Bob Glorioso managed at the
time.  Released c.a. 1982.  The board had its origin as a model railroad
controller created as a hobby project by an engineer in that group, and
was brought in and adapted for the VT180 as a quick time-to-market 
product.  (I subsequently subsequently re-adapted the board for
something completely different - and learned the history a few years later.)

The VT103 used the same idea, but with an LSI-11 backplane and T11 -
TU58 tapes & RT11.  But it was later, and not on the IA path.

The Rainbow was the replacement for the VT180 (c.a. late 82/early 83),
used RX50 diskettes and optionally, a st506 winchester drive.  It was
part of the triplet of machines, which also included the Pro 350 (pdp11)
and DECmate (PDP-8), that Ken Olsen pushed as the answer to the "cheap,
poorly engineered" IBM PC.  Besides being over-designed for the market,
all three suffered from being closed systems with hardware architectures
different enough from the standards (IBM PC/QBus/Omibus) to disable
commodity software.  Especially the Pro350, with its lobotomized P/OS
operating system (RSX with a horrible GUI) and limited menu of
application software.  (Eventually, RT was released, but too little, to
late.)  The DECmate never pretended to be anything other than a word
processor.  Ken's belief that quality would overcome price in this
market turned out to be very wrong.  And locking out existing software
made them niche products.

Both the Rainbow and Pro got minor upgrades, then died.  The DECmate was
the most successful of the three in that it did exactly what it set out
to do; no more and no less.  It got larger winchester drives and some
minor software updates, but basically kept chugging along until
technology - Apple, WordPerfect (and eventually Word) - provided
bitmapped fonts.  (But lost the gold-key UI in favor of the mouse...)

I don't think there was any real volume for the PC devices until the
DECstation IBM PC compatibles came along, which IIRC were
undistinguished Tandy buy-outs. 

And yes, the Z80 is a superset of the the Intel 8080, so perhaps you can
argue that it's not strictly IA.  But the Rainbow included one (you
could run CP/M on it, and it served as an I/O controller for the 8088). 
And in any case, the VT180 fit the common definition of "micro" at the time.

In any case, by no definition was the Rainbow "DEC's first micro".


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