FPGA VAX update

Gooijen, Henk henk.gooijen at oce.com
Thu Nov 3 07:19:23 CST 2005

> -----Original Message-----
> From: cctalk-bounces at classiccmp.org 
> [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Holger Veit
> Sent: donderdag 3 november 2005 14:08
> To: On-Topic Posts Only
> Subject: Re: FPGA VAX update
> woodelf wrote:
> > Bjørn Vermo wrote:
> >
> >>
> >> Apple comes to mind. You can pick up a G4 really cheap these days. 
> >> Whether you want to run BSD (OS X) or Linux is a matter of taste.
> >> IBM have some PPc development systems (Walnut if I recall right) 
> >> which can run both Linux and QNX, but I have no idea how 
> to get one 
> >> or what they sell for.
> >
> >
> > I guess nobody even considers building a computer from scratch. :(
> >
> About thirty years ago, when I was pretty much younger :-), I 
> built a classical TTL computer (with 74181 ALUs etc.) almost 
> from scratch, basically from schematic fragments from the TTL 
> databook and TTL cookbook and some electronics magazines; 
> well - if it were really from scratch, then even so "highly 
> integrated chips" like the 74181 were prohibited as well. 
> Looking back, this had almost all characteristics of a real computer.
> There are two aspects IMHO why this does no longer happen today:
> - what was a known magazine in the past, would today perhaps 
> realistically called "Un-Popular Electronics", the knowledge 
> of electronics from the ground up is dying out; and with the 
> continuing "digitalization" of technology, it is an ever 
> increasing hurdle to get started - the classical AM detector 
> radio I built as a newbie will nowadays no longer attract 
> anyone - you can get a gadget which is better by several 
> magnitudes for a fraction of the expenses you'd have for 
> soldering your thing.
> - The tools you have are too user friendly (!); i.e. you 
> could rather easily click something together, be it software 
> or VHDL code for an FPGA without ever needing to understand 
> what is really going on. The "soul of a new machine" guys 
> that traced glitches with a logic analyzer in a large 
> wire-wrapped TTL graveyard are gone - such a machine had the 
> necessary wow factor. No surprise when a VAX in an FPGA - see 
> subject - is not really interesting. It is possible - that's 
> it. But what does one gain? It is like solving a 10000 pieces 
> puzzle; spend time and don't learn really much.
> When Hillary climbed the Mount Everest 50 years ago, it was 
> something new, extraordinary. When tourist nowadays use sort 
> of stairways to reach the top (okay, it's not *that* extreme 
> now), it is just uninteresting. 
> But standing on the top, is still a challenge and an 
> experience for the individual. However, what we lost now is a 
> sense of wonder - that small ALU based TTL circuit was built 
> by myself, and I did it, and it is irrelevant that some idiot 
> could download a digital simulator and click the same circuit 
> together on a PC screen. I guess this is what makes the 
> difference between a real PDP-11 with some ridiculous 5MB 
> storage disks compared to a SIMH emulator running on a 3GHz Pentium.
> Watch the blinkenlights.
> Holger

Actually, I don't need to comment on this. Being a HAM radio amateur,
I did built a diode detector with a high-impedance headphone and a
varco plus coil. The experience *I made that*, and the first time
you hear a radio station are unforgettable impressions.
To add to your last sentence: I agree, but I have built something
that sits "in between". I use the SIMH software, but *added* a real
blinkenlight console! See my website. I do have several real PDP-11
models, but the blinkenlight SIMH is fun too (well, sort of).
Perhaps most of the fun was building it ...

- Henk, PA8PDP.


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