-----Original Message-----
From: Tony Duell <ard(a)p850ug1.demon.co.uk>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Saturday, October 23, 1999 4:51 PM
Subject: Re: OT: how big would it be? - PCBs at home
>> >Most shops cost a
>> >fortune to drill and etch a 10x8 card with a quantity of 2. Wire wrap
for
>> >this design is out of the question.
>> >
>>
>>
>> Sounds like you folks have been quoted a lot higher than I am paying for
>> prototype PCBs (if you had them done in a shop). Could be your the lack
of
>
>Well, you seemed to be implying you got them done for $1 or something
>(you claimed no set-up charges). I've never heard of pricing like that
>for one-offs...
Of course not.. on a small board like that... usually a $100 for 10 or so.
I have never paid a set up fee. Again, most shops will. I got lucky. This
shop and I have done quite a bit of business and I have helped him get some
solder fountain equipment for his tests...
I get an excellent rate... and it makes my prototypes boards bug free. I
like that!
>
>> ><I've found that the typical 'cheap' hobbyist's setup (disk of FeCl(3),
>>
>> Ferric Chloride is awful. If I *have* to do a quick small one-off board I
>> use very hot Ammonium Persulfate.
>
>I am reliably informed that the persulphate etchants break down if
>overheated. You might want to watch this (<50C?)
>
>
>> ><things like getting track widths right (!), which really messed up some
of
>> ><the striplines. We even had boards come back with the layers in the
wrong
>> ><order. We _very_ quickly learnt to (a) check everything and (b) do the
>> ><prototype ourselves if at all possible, to ensure the basic design was
>> ><sound...]
>>
>>
>> I know, on critical strip line work I sit down with the guy and we double
>> check the widths on the film.
>
>By which point you might as well have done the darn thing yourself...
>
I rarely do a board JUST for prototype/experimental reasons. Most of my
boards end up in production so it's a lot easier to iron out the bugs in the
prototype stage for production. I take it you do mostly one-off experimental
stuff.
>I learnt years ago that if you have to check everything that somebody
>else (PCB house, etc) is doing at every stage, then quite simply it's a
>lot faster and less hassle to do it yourself..
>
>>
>> That's my point exactly. I just don't have the time anymore to screw
around
>> with bad etches... even good etches can be bad in one small place causing
>
>A lot of minor faults can be patched over for prototypes...
>
Been there, done that.
>> all kinds of grief. I've had boards that we did in house that had
>> *microscopic* traces either shorting two pins or jumping two traces
>> together. I had one short so fine once that I could not see it by viewing
>> the board through light... I found it with a meter!
>
>I've had boards come back from a PCB house with a note saying that
>they've checked them against my netlist. And I've _still_ had internal
>shorts (which _weren't_ in the netlist).
>
>I got to the point of checking for real nasties (power-ground shorts,
>etc) with a meter, and then populating them, checking as I go. Quite
>simply, if you don't know what effect a short or open will have on your
>design then you don't really understand the design in the first place.
>But as ever, you check things a little at a time.
>
>>
>> And don't even get me started on those pre-sensitized boards... I've had
>> many with hair line cracks in the coating which causes LOADS of grief
after
>> the board is done and sometimes when the board is bent. :-(
>
>Hmm... Again, _for prototypes_ you should know just what effect such a
>crack would have. And then you can easily fix it (the signal reflection
>at a small repair like this will cause no problems at all!).
>
The idea of prototype to me is have the "ideal" conditions. Boards with
these problems are easy to find BUT many intermittant problems can come from
them. Ie: move the board and it craps out.
>Almost every board I have been involved with has been an experimental
>design/prototype. So cut-n-jumper mods are occasionally necessary anyway.
>Fixing PCB problems (which are _NOT_ common in my experience on homebrew
>boards) is no great hassle.
>
>
Okay that's different. I design products, final stuff. I design a board,
have about 10 prototypes knocked out.. sometimes some minor changes are
made, then it goes to production. My own prior company (outside my current
employer) did lots of this work so after a few prototypes were assembled I
would send the job to Taiwan with a schedule. I try to wirewrap when
possible on experimental type stuff but nothing beats quick PCBs.
Again, depends on your pocket $$, application, turn around time, and if it's
a hobby or serious $$.
>-tony
>
-----Original Message-----
From: Allison J Parent <allisonp(a)world.std.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Saturday, October 23, 1999 12:19 PM
Subject: Re: OT: how big would it be? - PCBs at home
><> Making PCBs at home is a ridiculous waste of time. I have a vacuum
lightb
>
>No it's not. Right now I'm doing a design that requires two sided and
>design rules down to 10mils.
Most of my designs are 10mil clearance. My PCB maker *likes* 10mil
clearance.
> There are three flat packs <64 pins and
>and daughter cards for more. The worst part was drilling the 2000 holes
>and a 3axis NC machine (home grown is not that hard).
Yuck.
>Most shops cost a
>fortune to drill and etch a 10x8 card with a quantity of 2. Wire wrap for
>this design is out of the question.
>
Sounds like you folks have been quoted a lot higher than I am paying for
prototype PCBs (if you had them done in a shop). Could be your the lack of
volume production in the past...I guess it depends what your time is worth
and the type of project. I'll still knock out quick single boards for
patches or small circuits. I do a lot of RF and high speed (50Mhz) design.
><I've found that the typical 'cheap' hobbyist's setup (disk of FeCl(3),
Ferric Chloride is awful. If I *have* to do a quick small one-off board I
use very hot Ammonium Persulfate.
><modelmaker's drill, rub-down transfers or a pen as the resist) is a total
><waste of time and energy. But the above stuff, which is easily possible
><to consider for serious home use (remember the sort of tools and test
><gear that I tend to own...) is certainly useable.
>
>I've done boards that way too. Even hand drawn simple RF layouts on the
>board with a SHARPIE pen (solvent based marker pens) for one ups.
>
I haven't tried that. I use Protel for everything.
><After a bit of practice, we could easily make striplines for ECL and/or
><RF stuff, SMD boards (no problem at all with SOICs, PQFPs, PLCCs, etc),
><and of course conventional pin-through hole. The ECL stuff clocked at
><200-300 MHz as well.
>
>The real trick is fine line stuff.
>
><[As an aside, we found some PCB companies were remarkable _bad_ about
><things like getting track widths right (!), which really messed up some of
><the striplines. We even had boards come back with the layers in the wrong
><order. We _very_ quickly learnt to (a) check everything and (b) do the
><prototype ourselves if at all possible, to ensure the basic design was
><sound...]
I know, on critical strip line work I sit down with the guy and we double
check the widths on the film.
>
>There are plenty of things that can really mess up an otherwise good design
>and bad etchs are hell to trace in when bring up for the first time.
>
That's my point exactly. I just don't have the time anymore to screw around
with bad etches... even good etches can be bad in one small place causing
all kinds of grief. I've had boards that we did in house that had
*microscopic* traces either shorting two pins or jumping two traces
together. I had one short so fine once that I could not see it by viewing
the board through light... I found it with a meter!
And don't even get me started on those pre-sensitized boards... I've had
many with hair line cracks in the coating which causes LOADS of grief after
the board is done and sometimes when the board is bent. :-(
john
>Allison
>
>>If you don't mind direct drive, there are TTL BCD-to-10 decoder chips
>>intended specifically for driving Nixie tubes. I just looked in my
>>newer databook at the 7445 and 74145, and they don't *say* "can directly
>>drive Nixies", but they do have high-voltage open-collector outputs.
>These "HV" decoders have 30 and 15 volt output devices. The one for neon
>lamps or Nixies was the 7441.
Thanks for refreshing my memory! Unfortunately NatSemi/Fairchild no longer
list the 7441 in their TTL lineup, but I'm sure a dedicated hobbyist could
find the parts at Halted Specialties or similar place.
Looking in the Fairchild books, the 7442 is still around as a DIP, and
combined with a transistor array it'd do a fine job as a Nixie driver.
The 74154, I see, is available as a SOIC for surface-mount. Hmm - now
all we need is a Hexadecimal Nixie! Did such a thing ever exist?
It'd be so cool to have fully formed A-F characters... though of
course there would be religious wars over upper vs lower case :-).
Tim.
>Wow! Thanks for the link. I happen to have a nixie tube strip that looks
>just like the one in the AL-1000. The one I have has 12 CD71 tubes (plus
>the minus bulb). On the bottom, there are characters in English and Katakana.
>Some of the part numbers are "IS-1", "Model 121" and "I2D-E2(B)". The
>Katakana appear to be representative of digits.
>
>I've always wanted to do something with this (like so much of my really good
>stuff, I've had it since I was a kid). I've just noticed that 12 digits
>is enough to make an ISO Date compatible clock/calendar (i.e., 199910220116).
>Is there a good reference around about how to drive a multiplexed neon array
>going from TTL to 90VAC?
Can you multiplex a Nixie display in the same way as a LED display? I've
never seen it done, but that certainly doesn't mean it isn't possible.
If you don't mind direct drive, there are TTL BCD-to-10 decoder chips
intended specifically for driving Nixie tubes. I just looked in my
newer databook at the 7445 and 74145, and they don't *say* "can directly
drive Nixies", but they do have high-voltage open-collector outputs.
They look more like open-collector lamp drivers than Nixie drivers
to my eye this morning.
I swear there were TTL chips which could directly drive (err, well, sink)
Nixie displays, but they aren't specifically called out in the newer
databooks. I've gotta find the box that has Don Lancasters _TTL Cookbook_,
I know there's an example in there.
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
--- Rick Bensene <rickb(a)bensene.com> wrote:
> > Casio AL1000 (discrete transistor, programmable, not scientific)
> > Casio AL2000 (ICs, much the same functionality as the AL1000)
> > ???? (All-in-one-chip equivalent)
>
> To check these out, see:
> http://www.geocities.com/oldcalculators/commal-1000.html
> This is a Commodore AL-1000. It's a Commodore-badged OEM version identical
> to the Casio AL-1000.
Wow! Thanks for the link. I happen to have a nixie tube strip that looks
just like the one in the AL-1000. The one I have has 12 CD71 tubes (plus
the minus bulb). On the bottom, there are characters in English and Katakana.
Some of the part numbers are "IS-1", "Model 121" and "I2D-E2(B)". The
Katakana appear to be representative of digits.
I've always wanted to do something with this (like so much of my really good
stuff, I've had it since I was a kid). I've just noticed that 12 digits
is enough to make an ISO Date compatible clock/calendar (i.e., 199910220116).
Is there a good reference around about how to drive a multiplexed neon array
going from TTL to 90VAC?
-ethan
=====
Infinet has been sold. The domain is going away in February.
Please send all replies to
erd(a)iname.com
__________________________________________________
Do You Yahoo!?
Bid and sell for free at http://auctions.yahoo.com
> IIRC, the 8080 was about 4000 MOSFET transistors. If you implemented it
> with individual FETs, and packed it densely, I think you could fit it in
> a 10.5" high rack space easily, and a 5.25" high rack space with difficulty.
> Of course, you'll need plenty of forced air cooling. From a serviceability
> point of view, building it less densely is clearly better.
True.
> If you implemented it with bipolar transistors configured as saturating
> logic, it would require perhaps twice as many transistors and a lot more
> resistors for TTL logic, or 50% more transistors, a lot of diodes, and a
> lot of resistors for DTL logic.
Also true. A lot of the power estimates have been based on the assumption that
we have bipolar transistors. What about discrete mosfets? We could do NMOS or
even CMOS designs directly that way...
I liked Hans's suggestion (which I have now deleted, alas) of a museum exhibit
with three identical computers, but with processor as single chip, board of
gates, and rack of trannies for comparison. It does provide a service that you
couldn't get another way...
... or could you? Didn't PDP8 come in all three versions?
I've often wondered if you could build a transistorised computer without pcbs at
all. You know, trannies on tag board, little plugs bolted onto the ends (or on
flying leads) and so on... I was assuming ECL for two reasons - if you use
early transistors (Ge), ECL would probably be the only way to go at all fast;
and ECL gives the advantage of easy differential line drivers and receivers for
long interconnects.
Philip.
This E-mail message is private and confidential and should only be read
by those to whom it is addressed.
If you are not the intended recipient, you are hereby notified that any
dissemination, distribution, copying, reproduction, modification or
publication of this communication is strictly prohibited. Please delete
the message from your computer and destroy any copies.
This message is not intended to be relied upon by any person without
subsequent written confirmation of its contents. This company therefore
disclaims all responsibility and accepts no liability of any kind which
may arise from any person acting, or refraining from acting, upon the
contents of the message without having had subsequent written
confirmation.
If you have received this communication in error, or if any problems
occur in transmission please notify us immediately by telephone on
+44 (0)2476 425474
-----Original Message-----
From: Chuck McManis <cmcmanis(a)mcmanis.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Tuesday, October 12, 1999 10:51 PM
Subject: Re: pdp8/f
>Having already inspected and turned down this junker be it known that the
>system doesn't work. I wasn't able to isolate the problem to the front
>panel or the CPU but the boards didn't work. The 8/E chassis that went for
>around $400 on Ebay was a better deal. Consider Keyways for PDP-8 boards as
>well. I told Easy that the 8/f wasn't worth more than two or three hundred
>tops.
That 8/e chasis went for $1300 this morning!
>
>--Chuck
>
>At 09:13 PM 10/12/99 -0500, you wrote:
>>OK, the PDP8/f is in California. As i mentioned before they want $600
>>for it. This is what it contains:
>>
>> > 1 M8330
>> > 1 M8310
>> > 1 M8300
>> > 1 M837
>> > 1 M848
>> > 5 M1709
>> > 2 M8655 (NOT THE TWO LISTED BELOW)
>> > 1 M849
>> > 1 M8320
>> > AND 1 DATARAM DR118 CORE MEMORY
>>
>>I'm still dealing with them over the PDP8 boards I want to buy, which is
>>why i'm hesitant to mention the company at the moment.
>>
>>-Lawrence LeMay
>
>
<I swear there were TTL chips which could directly drive (err, well, sink)
<Nixie displays, but they aren't specifically called out in the newer
Try 7441 binary to decimal nixi driver. And the V++ should be 120-130V
with a diode clamp at 90V for std nixis. The lower voltage tube that work
at 90-100V you can skip the clamp.
I stilll keep a pot load of them, I have test gear (some 25+ years old)
that use nixi tubes, such as my Yasu 355 frequency counter.
Muxing nixies... can do it but the rules (voltages and rates) are horrid.
First of the formed segment types don't mux well at all they are slow.
The dot matrix tubes (burroughs self scan) were the most common muxed
"neon glow" displays.
Allison
<> Making PCBs at home is a rediculous waste of time. I have a vacuum lightb
No it's not. Right now I'm doing a design that requires two sided and
design rules down to 10mils. There are three flat packs <64 pins and
and daughter cards for more. The worst part was drilling the 2000 holes
and a 3axis NC machine (home grown is not that hard). Most shops cost a
fortune to drill and etch a 10x8 card with a quantity of 2. Wire wrap for
this design is out of the question.
<I've found that the typical 'cheap' hobbyist's setup (disk of FeCl(3),
<modelmaker's drill, rub-down transfers or a pen as the resist) is a total
<waste of time and energy. But the above stuff, which is easily possible
<to consider for serious home use (remember the sort of tools and test
<gear that I tend to own...) is certainly useable.
I've done boards that way too. Even hand drawn simple RF layouts on the
board with a SHARPIE pen (solvent based marker pens) for one ups.
<After a bit of practice, we could easily make striplines for ECL and/or
<RF stuff, SMD boards (no problem at all with SOICs, PQFPs, PLCCs, etc),
<and of course conventional pin-through hole. The ECL stuff clocked at
<200-300 MHz as well.
The real trick is fine line stuff.
<[As an aside, we found some PCB companies were remarkable _bad_ about
<things like getting track widths right (!), which really messed up some of
<the striplines. We even had boards come back with the layers in the wrong
<order. We _very_ quickly learnt to (a) check everything and (b) do the
<prototype ourselves if at all possible, to ensure the basic design was
<sound...]
There are plenty of things that can really mess up an otherwise good design
and bad etchs are hell to trace in when bring up for the first time.
Allison
While going through some stuff I ran across a specifications folder for
this kit. It has circuit diagrams for the individual units and the front
panel. Also a couple of articles on how it works.
If anyone needs this info I will scan it and forward it.
Regards
Charlie Fox
Charles E. Fox
Chas E. Fox Video Productions
793 Argyle Rd. Windsor N8Y 3J8 Ont. Canada
email foxvideo(a)wincom.net Homepage http://www.wincom.net/foxvideo
