FPGA VAX update

[Scott Stevens]

On Wed, 02 Nov 2005 16:15:34 -0500
Allison <ajp166 at bellatlantic.net> wrote:

> >
> >Subject: Re: FPGA VAX update
> >   From: woodelf <bfranchuk at jetnet.ab.ca>
> >   Date: Wed, 02 Nov 2005 13:24:07 -0700
> >     To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
> >
> >Allison wrote:
> >
> >>Ego a 16bit machine September 1985.  There was another article whose
> >>focus was microprogramming vs sequential machine control and that used
> >>the TOY1 archetecture. There were others described in TCJ Dave Brooks
> >>simplex III comes to mind.  There are others.
> >>
> >>  
> >>
> >Toy I had forgotton.
> >Since TJC is now defunct are there any on-line copies of it  I have read 
> >the simplex web site.
> 
> Dave Brooks has the simplex story on his site (along with the P112).
> 
> There is also a web ring for homebrew CPUs, quite a bit of diversity 
> out there but PDP-8 is common along with minimalist machines for teaching.
> 
> However the most interesting is the Block 1 AGC (apollo guidence computer).
> 

Depending on how much 'from scratch' people feel is necessary, it's also interesting to roll your own computer using an off-the-shelf processor (or multiples).  I have a simple 8088-based SBC design wired up and waiting for motivation to put together some test firmware.  The main thing that has kept me from bringing it up is the difficulty in getting x86-based machine language development tools going.  I'm used to little 4 and 8-bit assemblers where you can plop down a few ORG statements and have it all resident in a ROM, and almost all the x86 asm tools start from the assumption you are running on DOS and have no direct control of the memory map.

Z80 designs are also fun and easy.  And I still have those tubes of 6100 processors. . .

Certainly using a micro is by no means as cool as making your own machine from small and medium-scale logic, though.  I think it would be neat to build one using discrete transistors.  Not as difficult as a valve-based design, but just as deep into the circuitry.


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