OT(?): Emulation XKCD

Charles Anthony charles.unix.pro at gmail.com
Thu Oct 31 17:15:10 CDT 2019

On Thu, Oct 31, 2019 at 9:23 AM Warner Losh <imp at bsdimp.com> wrote:

> On Thu, Oct 31, 2019 at 8:15 AM Zane Healy via cctalk <
> cctalk at classiccmp.org> wrote:
>> Anything from bitsavers relevant?
> http://bitsavers.org/pdf/honeywell/
Sadly no.

There are two models of FNP, the 355 and the 6661.

The 355 is an 18-bit machine with an architecture very similar to the 635
(and thus its descendent DPS8/M); I tend to think of it as a 635 sawed in
half. The code that runs the 355 is assembled and linked on the Multics
host and downloaded into the 355 at system startup.

We have that source code, and reasonably good documentation on the 355 CPU
and on the Direct Interface Adaptor which connects the 355 to the DPS8/M We
do not have documentation on the I/O controller or on the peripherals, nor
do we any other software (such as diagnostics). The 355 emulator is at the
point where it will run the first few dozen instructions.

The 6661 is built around a Honeywell Level 6 16-bit minicomputer. There is
a lot of documentation on the hardware, but we have no idea how it was
programmed to be an FNP. The 355 18 bit code obviously will not run; so
either there was a 355 emulator running on it, or there was a seperate
firmware program that we do not have.

The 355 I/O controller is probably quite similar the the DPS8/M IOM, and
with some reverse engineering of the firmware, a reasonably correct
implementation could be done. The peripherals (serial i/o multiplexor,
operators console) are conceptually straight forward and should yield to
the same approach.

There are some messy implementation details that need attention, mostly
things like interprocess communication widgets to handle the interrupt
request signals between the FNP and DPS8/M.

What is needed for 355 implementation:
    IO controller docs.
    HSLA (High Speed Line Adaptor) docs.
    Diagnostic software, if it ever existed.

What is needed for 6661 implementation:
    A Level 6 emulator.
    The FNP software.

-- Charles

>> Zane

X-Clacks-Overhead: GNU Terry Pratchett

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