[ih] byte order, was Octal vs Hex, not Re: Dotted decimal notation

[John Day]

Good thing Bell went the direction he did.  DG never understood how to do stacks and stacks were crucial to what we were building on the PDP-11.  I always thought that putting auto-increment/decrement on the same side of the instruction was pretty dumb.

Bell knew what he was doing. Now if they just understood it a bit better when then added the Mark Stack on the 11/45 life would have been even better.

> On Dec 30, 2020, at 11:18, Bill Ricker <bill.n1vux at gmail.com> wrote:
> 
> 
> 
> > But of course, there is an alternative history, as so often:
> > https://history-computer.com/ModernComputer/Electronic/PDP-11.html <https://history-computer.com/ModernComputer/Electronic/PDP-11.html>
> > which states that the actual design was done by Harold McFarland.
> 
> From memory ...
> 
> The grand architecture and the outline of the ISA of the PDP-11 is Bell's:
>  it was his Register Transfer Logic theoretical / simulator machine for the grad course he taught at CMU. (Part of DEC's deep relationship with CMU.)
> 
> McFarland made it real, but first proposed a design to make it real.
>  
> (Does this echo McCarthy's LISP being interviewing as only a chalk-board language, until a student implemented it? Yes!)
> 
> Bell as DEC VP Engineering (having lead multiple 18- & 36-bit mainframe-ish projects, incl PDP-6,-10) had to choose one of McFarland's and Edson DeCastro's designs for DEC's next product, a 16-bit mini product.  
> 
> DEC Marketing might have preferred E deC's 16-bit expanded PDP-8 architecture option, with potential migration path for existing customers.
> And it would have been the safer bet,  as Castro and the PDP-8 team had recent minicomputer experience that Bell & McFarland did not.
> (Of course the departmental timesharing market that the 11 would open couldn't be foreseen, it wasn't just going to steal embedded and instrumentation sales from the 8.)
> 
> Bell was pleased to pick the design based on his own academic theory. 
> 
> DeCastro was not pleased and so left and realized his design as the DG Nova. (I don't recall if it sold well into existing PDP-8 shops or not, but it at least sold well enough.) 
> 
> (DeCastro nearly sank DG by avoiding recapitulating the offense, he green lighted a 32-bit expansion of the 16-bit expansion of the original 12-bit design, which project failed. /Soul of a New Machine/ records the Eagle, the skunk works greenfield 32-bit design that worked.
>    Small world, I worked with some of the Eagle OS team elsewhere,  who recounted that Kidder interviewed them too, but dispared of explaining the tribulations of OS-writing in popular literature, so focused on the MicroKids.
>   One of whom was on the ACM Northeast Regional Conference committee with me. Alas while we produced two Proceedings, there was only one conference. If only we'd had Zoom-like tele-conferencing then.  Other brands are available! We'd hoped the recession reduction in travel budgets would make a regional conference attractive; nope, we sold one booth and had more speakers than prepaid attendees registered, so we reluctant canceled. But the accepted papers were published, and a copy went to everyone who'd registered. Mildly collectible? 😆)
> 
> (Speaking of collectible. Somewhere around here, I have a PDP-6 ALU bit-slice board signed by Gordon, with one of the feont-side bus-straps. Terrible design for Field Service, hard to board-swap!  I was a young volunteer at TCM Marlboro and TCM Boston when Dr Mrs Gwen Bell was in charge, and helped Dr Mr Gordon in TCM housecleaning prior to the move to Boston. He was amused to hear i used his book for VCs and Founders as a guide to evaluating which startups to work for.)