Tony Duell <ard(a)p850ug1.demon.co.uk> wrote:
>Punched cards have one major design bug IMHO that's not shared by paper
>tape. There's no 'column reference' on a card.
>It's therefore almost impossible to make a hand-pulled card reader.
Come to think of it, perhaps a sub-$50 B/W QuickCam would make a
cheaper reader than a scanner. You could aim it at the card, in a
frame, and drive it by hand. Front-lighting and scanning can put
a non-card color behind the holes. Or you could back-light with
infrared LEDs and take advantage of chip-cam IR sensing. Unlike
phototransistor or mechanical solutions, it's not dependent on
particular card geometry.
I know the video/scanning route sounds like technological overkill.
What's wrong with that? :-) It reminds me of my day-dream to
rescue audio cassette data using PC sound card digitizing.
I like these novel solutions because they are less dependent on
esoteric hardware, and the core - the software - is more portable
and transportable into the future and to users who need it.
Sounds like Ethan has more spare time than I do, though!
- John
Jefferson Computer Museum <http://www.threedee.com/jcm>
>>
>> Could someone tell me what the configuration of individual gates
>> is (one of them, at least) for binary addition (or provide an EASY
>> TO FIND reference)?
> I'll give you the equations, you can draw the gates yourself (it's
> getting late...)
> lots of stuff about adders
There is a much easier one chip solution, the brute force approach.
Take a TTL PROM, size dependent on how big an adder you need, use the
address lines as terms A and B, and use the outputs as the result. For
instance, for a 4 bit adder, use a 256x8 TTL PROM, lower 4 address bits
are A, upper 4 are B, and the 8 output lines are the result (only 5
used, 4 plus carry). Program the PROM with all the possible results.
You can also make a poor man's multiplier or divider the same way. For
a multiplier all 8 output lines would be used.
Jack Peacock
I'm curious about the various home/small business computer standards.
I know about the PC standard *sigh*. There was also the MSX standard
which involved a Z80 and 64K ram, I think. What other ones were there?
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<True. If you write the program to keep careful time (and reject cards wi
<fewer than 80 chars), it _might_work. There is, of course, a brute-forc
<approach - 960 phototransistors. Additionally, one could build a 4 dpi
<scanner (12 pixels and a stepper motor). With the steppper from a 5.25"
<drive and either a mechanical amplifier (lever) to pull the 7" stroke or
<either a) multiple 12-bit sensors or b) one 80-bit sensor w/3" stroke,
<it wouldn't be that hard to make, not that I have the time to make a
<contraption of that complexity.
Ah gads you guys do it the hard way. Take a stepper from something and
put a roller on it with a diameter such that one step will move the card
forward one column. Then all you need is one rows worth of
phototransistors. I forget the punched card orgainization but a parallel
port (printer) off a PC should be enough bits.
For hand pulled it's a row of phototransistors for reading the column and
one phototransistor for each row.
V--to read column
=============================================================guide rail
+
+
+
+
+++++++++++++++++++++++++++ <<<<<<<direction of motion (96 needed)
^ +
| +
/ +
| +
|=============================================================guide rail
^optos to read the leading edge of the card for column clock, spacing
is such that each one is obscured as the column is over the column
leds making it self indexing. It's possible to go very fast.
Oh the only difference with hole vs mark sense is transmittance or
reflective sensing.
Allison
I'd love to write a program to "OCR" punched card images. Now, if
I only had some spare time. :-)
Scanners are cheap and ubiquitous. You could lay several cards on the
scanner at once, perhaps placing a specially-colored paper on the
normally white reflective lid, and presto - like chroma-key on video,
you can easily "see" the borders, index notch and holes. I wonder if
any of today's "paper port" auto-feeding cheapo scanners would handle
a punched card - I don't see why not.
It could save the card data in Jone's proposed file format. One advantage
of this system would be that it could handle aged cards that some physical
imperfection (like dents from rubber bands, folds, worn edges, etc.) that
might jam a card reader.
- John
Jefferson Computer Museum <http://www.threedee.com/jcm>
Don't write to me on this, write the the fellow below if this interests
anyone.
--------------------------------------------------------------------------
Cliff Boyer <homeline(a)ezl.com>
Alton, IL USA - Tuesday, April 21, 1998 at 00:11:30
I for got something a minute ago.
I found in a 2nd hand store a book that may be of some intrest.
It is titled "The IBM 5100 PORTABLE COMPUTER, A Comprehensive
Guide For Users and Programmers". Hard Bound, Published 1977.
Deals with BASIC & APL languages' and basic overview of computer.
Excellent condition.
I don't need it, so it's first come first served!
$5 would cover book & shipping!
--------------------------------------------------------------------
Russ Blakeman
RB Custom Services / Rt. 1 Box 62E / Harned, KY USA 40144
Phone: (502) 756-1749 Data/Fax:(502) 756-6991
Email: rhblake(a)bbtel.com or rhblake(a)bigfoot.com
Website: http://members.tripod.com/~RHBLAKE/
ICQ UIN #1714857
AOL Instant Messenger "RHBLAKEMAN"
* Parts/Service/Upgrades and more for MOST Computers*
--------------------------------------------------------------------
Wasn't there someone on here a while ago looking for 1702's? Whoever that
was, you might want to try Jameco(http://www.jameco.com), the catalog I
have shows them at $1.95 each, but I don't know how many they have left, if
any...
--------------------------------------------------------------
| http://members.tripod.com/~jrollins/index.html - Computers |
| http://www.geocities.com/Area51/Lair/1681/ - Star Trek |
| Orham(a)qth.net list admin KD7BCY
|
--------------------------------------------------------------
I have just got a Sun 2 clone workststion (Sun boards in an unbranded box)
and it won't boot.
If any one can decode the 'heartbeat' LEDs here is the code.
Looking down at the edge of the CPU board:
=============[Empty connector]=========[oxxx ooox]====================
where x is LED off and o is LED on.
I would like to mend this myself if possible. If it is going to require
component level diagnosis and repair then please bear in mind that I
haven't used a soldering iron or meter in anger since I was mending
televisions at school - when they all had 405 lines on the screen and
valves.
Regards
Pete
Tony Duell wrote:
> Punched cards have one major design bug IMHO that's not shared by paper
> tape. There's no 'column reference' on a card. On a tape, you can strobe
> off the sprocket track, but alas on a card a totally unpunched column is
> valid (=a space character).
>
> My Documation M200 uses the leading edge of the card as a reference. It
> then counts pulses from a toothed wheel/pickup head on the card roller
> shaft to deteremine where the columns should be.
>
> It's therefore almost impossible to make a hand-pulled card reader.
I rather liked Allison's long array of photodetectors (of whatever
flavour) to tell you where the leading edge is.
But why not have the same wheel to determine the position, but the card
turns the wheel rather than vice versa? You lose the non-contact
element of hand pulling, but you don't get motors chewing delicate
cards.
Philip.
-----Original Message-----
From: Tony Duell <ard(a)p850ug1.demon.co.uk>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Tuesday, 21 April 1998 12:27
Subject: Re: 5150
.
.
>It can be a little depressing to read a manual for a machine that you
>know you'll never own or even see (like the PDP6 schematics that I
>downloaded a couple of years ago). But I still think it's better than
>knowing nothing about the machine/
Thats why I keep my NeXT book!
