[TUHS] C from 1980 binaries

[Lawrence Stewart via TUHS]

> On Nov 2, 2026, at 11:00, Clem Cole via TUHS <tuhs at tuhs.org> wrote:
> 
> On Mon, Nov 2, 2026 at 1:49 AM Marc Donner <marc.donner at gmail.com> wrote:
> 
>> That educated me about the bus, so years later I recognized that the
>> Motorola 68000 had essentially implemented it faithfully, with the
>> exception of making the Sync signal active-low instead of active-high (a
>> true blessing in TTL days).
>> 
> Yup, it is very close and was intended to be, as it was a model, but the
> designers were careful not to make it exactly like it.  Remember, what
> became the 68000 was a skunkworks project and >>not<< an 'official' project
> at Moto.   Les Crudele, Nick Tradenick, and a couple of others had joined
> Moto from Schlumberger, where they had been interfacing PDP-11 control
> systems for the oil drilling industry and were extremely familiar with both
> the PDP-11 ISA and the Unibus. But Les says he and the team were very
> careful.  The bet they had with Tom Grunner was that they could basically
> build a PDP-11 on a single chip using Motorola's current process
> technology. Tom was interested enough to let them try in the back of the
> lab.  But those folks (particularly Tom, as I understand it) were all
> extremely aware of the CalData lawsuit.  Thus, they made sure the ISA and
> bus were 'different enough'.  For instance, Nick made the instruction set
> use the same addressing modes and functions, but isn't the same, using
> address and data registers instead of general registers.    I've long
> forgotten the specifics of the differences, but similarly Les said he spent
> a lot of time thinking about what we could use from the Unibus and QBUS,
> but still be different enough that they would not be taken to court as
> CalData had.  The fact that, a few years later, Ken O'Mohundro put a 68010
> on a QBUS fairly easily is living proof it wasn't that far off.
> 
> The rest of the story of how 68000 went from being a skunkworks project to
> a real product is cool, and I am honored to have helped play a small part
> in that story with the TekLabs's Magnolia system; but it's not relevant
> here.

It is not well known, but the first DEC Systems Research Center “Firefly” multiprocessor 
was actually a 68010. It drove a QBUS for I/O.  We never went into production because we 
were able to get 78032 Microvax II chips in time.  This would have been late 1984 or 
early 1985 IIRC.

Chuck Thacker did the hardware design for the 68010 version, and I wrote the 
boot roms.  https://en.wikipedia.org/wiki/DEC_Firefly

Not exactly TUHS, but the connection is the Firefly OS would run standard Ultrix-32 binaries.