Ethan Dicks wrote:
While I can recommend a real PCB if the setup costs
and the per-sq-in
costs are not killing you (price an Omnibus or Unibus-sized 4-layer board,
complete with gold fingers!), personally, my WW overhead isn't terrible:
I rescued all the prototype hardware from my former employer when they
went bust - I probably have three lifetimes worth of WW sockets. When
I do a project, the only part I have to spend money on is the wire.
Out here the only parts store is Radio Shack or wait 6 months to get to
a larger city. Thus mail order and internet shopping works for me. With
wire wrap I would spend too much time hunting for bad wires/connections
or paying $$$ for parts. A PCB is a simple upload of my gerber and drill
files.
My last project is a good case-study for expense vs.
time. I wanted to
replicate a scoreboard from a Dragon's Lair/Space Ace. I tried to find
one on ePay, but they only come up occasionally (every couple of months).
I decided to build one. I started with a couple of digital pictures,
a parts list and a schematic. Since the board was approx 6"x9", it
would have been somewhat expensive for a commercially-made PCB. There
are still plenty of surplus units out there that sell used for under $50
when they are available, so it would be cheaper to wait for a sale than
to have a professional PCB created unless the new PCB added value somehow.
I had the blue perfboard (from when the MicroCenter got rid of all of their
prototyping hardware at 80% off list!), the wire and the discrete
components. I had to purchase the LEDs ($0.65 each) and the driver chips
(a few bucks each). Total out-of-pocket expense was <$25. I probably
pulled about $15-$20-worth of supplies out of my parts bins.
Construction took place over several evenings, watching the sci-fi channel,
tacking down point-to-point connections (didn't have the vertical
clearance for socketing the LEDs). I'm pleased that it worked the first
time! - pictures at
http://penguincentral.com/retrocomputing/retrogaming/
under the "LED Scoreboard" link. Mostly, it's pictures of the glow of
the LEDs, but there's one out-of-focus, flash-burned picture of the
perfboard and yellow wire in there (the Apple QT150 has about a 24" min
focal distance without the strap-on lens).
nice (see ps at bottom)
The upshot was that if this were being done for anyone
but me personally,
it would have been an economic disaster. Nobody would have paid me a
reasonable amount for that much work - it would have been much cheaper
to go to an arcade service company and *buy* a used scoreboard than spend
10+ hours wiring up a board. It would have been much cheaper than that
to wait out the next wave of offerings on eBay (which I accidentally did -
the project took so long to complete that I _did_ pick a real one up for
around $30, after I was 95% finished with my replica. The good news is
that it made a nice functional benchmark to prove that mine worked).
So I chose to trade my time for semi-instant gratification. I would
have loved to have done a PCB, but I chose not to spend the time with
layout tape and a blank board, and I chose not to pay to register a
demo-ware layout package so I could make a 6"x9" board.
More like 3" x 4". Easytrax (dos) is still out there and runs fine (and
free) if you don't need autorouting.
If I were to
make the new PDP-8 design that kicked off this whole thread, I'm not
sure if I'd get professional boards (~$200/set, in small quantities,
according to the designer, for a couple of 4-layer boards) or I'd
point-to-point it.
Is 4 layer boards really needed?
I like the PDP-8 but am unhappy that a 12/24 cpu never hit the
monolithic chip market. Now with a FPGA I have a cpu design that is a
'what if' computer that really could have replaced the IBM PC at that
time. ( Early 1980's )
In terms of $$$/hour, even $200 for a board set
is cheap. In terms of a discretionary hobby, $200 is a lot to divert
from other projects when I already _have_ a working PDP-8. With that
kind of money, I could start trolling for a Qbus SCSI controller!
Well I don't but remember with out the proper I/O a pdp-8 is NO FUN.
While I can run a emulator 100x of times faster than the real thing it
is not the same with out a TTY chugging away on paper tape.
Back to the initial topic, though, I'd love to get
a good buy on a dozen or
so spools of kynar-coated wire. I'd prefer an assortment of colors, but
I'd take it in whatever I could get - yellow, red, white...
Anyone have a lead on any surplus places that have it for a few bucks
a spool?
While B.G.Micro does NOT have wire wrap wire it does have a few
interesting odds and ends and some of the more older chips out like 16k
dram/floppy disk controlers/8 bit cpu's.
www.bgmicro.com
PS. Just after I finished writing this I looked up the scoreboard and
noticed you use BG micro already.
--
Ben Franchuk - Dawn * 12/24 bit cpu *
www.jetnet.ab.ca/users/bfranchuk/index.html