source: t29-www/en/development-projects.php @ 367

Last change on this file since 367 was 358, checked in by sven, 11 years ago

Links in den Entwicklungsprojekten korrigiert.

Alle gehen jetzt wieder an die richtigen Stellen, nur das PDF zum Lochkarteneditor ist noch nicht hochgeladen und der Link stimmt daher noch nicht (nur im Deutschen).

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File size: 10.3 KB
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1<?php
2        $seiten_id = 'entwicklungsprojekte';
3        $version = '$Id: development-projects.php 358 2013-03-08 16:15:57Z heribert $';
4        $title = 'Development Projects';
5       
6        require "../lib/technikum29.php";
7?>
8
9<h2>Development Projects</h2>
10
11<p>This page lists some of our development projects where old hardware meets modern
12computer equipment. All projects are selfmade, with partly enormous hardware and
13software efforts, like routed PCBs, kernel drivers and microcontrollers.
14<br/>Upcoming projects:</p>
15<ul>
16  <!-- Done: -->
17  <!--<li>punch card I/O with AVR ATmega microcontrollers via RS232 to computers,
18      Qt platform independent processing, with various hardware</li>-->
19  <li>Anelex printer interface to the Bull Gamma 10 computer (uC based)</li>
20</ul>
21<br/>
22
23<h3><a name="papertape"></a>Paper tape processing with contemporary computers</h3>
24
25<p>We were often in a situation when some data stored on a punched paper needed
26to be sent over long distances. Having Internet access and e-mail, that's no matter
27for todays computers, once you can read in paper tapes. The other way around,
28punching new or modified data on punched papers is also a frequent need in our daily
29business. <br/>Therefore we initiated the <b>Paper Tape Project</b>, having the
30pronounced goal to handle paper tapes with contemporary computers, that is, to
31read, change and write (punch) them.</p>
32<p>We use comparatively new punched paper devices that already feature a Centronics
33interface at TTL level. Unfortunately the devices (in detail: reader
34Ghilmetti FER 201, puncher FACIT 4070) didn't yet implement the Centronics
35common standard from the 1970s (officially standardized as IEEE-1284 not until 1994),
36therefore simply connecting those devices with a standard parallel port printer cable
37won't do the job.</p>
38
39<div class="desc-left">
40   <img src="/shared/photos/rechnertechnik/fer201.jpg" width="239" height="148" alt="Photography of the paper tape reader Ghilmetti FER 201" />
41   <p class="bildtext" style="width:239px;"><b>Ghilmetti FER 201</b> reader with framework for reading zig-zag tapes</p>
42</div>
43
44<p>The very first step was to read the manual carefully to assemble a specially wired
45cable to connect the punch card device with the parallel port of a PC (commonly known as
46"LPT port", a standard port on PC motherboards just a few years ago). Since the devices
47don't implement the standarized hand shake, the second step was to implement a suitable
48driver to emulate the right communication behaviour for the punch card devices.</p>
49
50<p>Development started on the free GNU/Linux Operating System where we used the ppdev
51framework of the Linux 2.6 kernel series to program a user space driver in the programming
52language C with a little effort compared to a real kernel space driver.</p>
53<div class="desc-right">
54   <img src="/shared/photos/rechnertechnik/facit4070.jpg" width="192" height="313" alt="Photography of the paper tape puncher FACIT 4070" />
55   <p class="bildtext" style="width:192px;">The legendary puncher <b>FACIT 4070</b></p>
56</div>
57<p>The parallel port consists of three 8-bit hardware registers: a bidirectional data
58register, a control register and a signal register. Since paper tapes are made of
598-bit words (octetts), we just connected these eight bits on the data register to save
60them directly to one byte in the computer. Using the control and signal pins, we could
61implement a interrupt (device cycle) driven communication, since the status register
62features one interrupt enabled bit (strobe). Our devices punch at 80 chars/sec and read in
63250 chars/sec, so even older PCs can easily run the driver programs.<br>
64
65As already told, there's not really the question how to model punched papers on
66computers, since they use the same word length (8 bit) and computer files are
67conceptually the same as paper tapes: byte arrays. A 250 byte binary file therefore
68represents a 250 chars long punched paper. Thus processing punch card files
69with Unix command line tools or hex editors is very easy. To speed up the workflow,
70we wrote some simple perl scripts to label paper tapes. Afterwards we wrote a
71graphical editor, called "Paper Tape Editor", where binary files could be visualized
72and directly edited as paper tapes on the screen. This program was written in C, using
73the Gtk+ toolkit. After writing drivers for the Microsoft Windows Operating System,
74this program was extended to the "Paper Tape Suite" to read, edit, save and punch
75paper tapes graphically. That way every possible procedures with paper tapes can be
76performed with ordinary PCs.</p>
77
78<p>You can get further details with a lot of documentation material on the homepage of
79<a class="go" href="http://dev.technikum29.de/projects/wiki/PaperTapeProject"
80>The Paper Tape Project</a>. The source code was released as open source can be checked
81out from the <a
82href="http://dev.technikum29.de/projects/browser/projects/paper-tape-project/trunk">technikum29.de
83subversion repository</a>.</p>
84
85<h3><a name="punchcard"></a>Reading punch cards with contemprary computers</h3>
86<p>There is an historical storage media that is even more important than paper tapes:
87Punch cards. They were the one of the pillars of early mass electronic data processing
88and were used for saving data and program executables. Based on the <i>Paper Tape Project</i>,
89we started the <i>Punch Card Project</i> with the similar target of reading, editing and
90punching punch cards.</p>
91
92<p>When connecting these small paper tape devices (shown above) directly to modern
93personal computers via the parallel port ("LPT"), we noticed they were too slow for
94communication. Having modern GHz powered high end computers, how's that possible?
95<br/>The real cause for this performance is the software and hardware design of
96contemporary personal computers. They are conceptually designed for processing huge
97amounts of data and high speed calculations, but no more for short latencies with I/O
98handling. Actually, all time-ciritcal parts in modern high speed communication
99protocols (like USB, Ethernet, Firewire, etc.) are implemented in hardware. Software,
100on the other side, features more and more abstraction levels, so there's no more
101real-time operation even at kernel space.
102<br/>There are real-time operating systems, indeed, but by using such an operating
103system, the computer would be dedicated to communicating to the device. This is not
104neccessary. There is a (not even young) branch of computers which perfectly match
105all the criteria mentioned: Low latency, fast I/O, fully deterministic. Microcontroller
106are these low cost processors, a single chip featuring a lot of peripheral equipment.</p>
107
108<div class="desc-left">
109    <img src="/shared/photos/rechnertechnik/documation-m200.jpg" width="300" height="215" alt="Photography of the Documation M200 pneumatically Punch Card Reader" />
110    <p class="bildtext" style="width:300px;"><b>Documation M200</b> card reader (this one implemented by WANG)</p>
111</div>
112<p>We are using an ATmega microcontroller made by Atmel AVR. Most of the 40 digital I/O
113pins are directly wired to the electrical Input/Output of the punch card device
114<i>Documation M200</i> (featuring a pneumatic card feed). On the other side of the small
115development board there is the RS232 port ("serial port"), communicating to the computer.
116This small board is actually so small that it fits right into the device's cabinet.
117Running with 8&nbsp;MHz, the microcontroller is easily capable of hard real-time
118communication (300 cards/minute) and serving 4kB RAM, there is enough space for buffering
119a lot of punch cards until they can be sent to the virtually lazy computer via RS232.
120This is a quite old industry standard for serial data transportation, but since its very
121easy and robust, RS232 is quite perfect for such an interface. Using contemporary USB
122was no option since it's very complex and bulky (above all, there are cheap RS232-to-USB
123interfaces).</p>
124
125<p>We wrote a program for the microcontroller that implements the device driver to the
126punch card device. Now having an electrically specified interface to the computer (RS232),
127how should we communicate to the computer (automatically)? Furthermore, in which way
128should we represent a punch card with binary digits (zeros and ones)?
129<br/>While modeling 8 bit paper tapes into 8 bit bytes is trivial, a punch card, having
13080 columns with 12 rows each, is much more complex. Therefore we wrote the
131<a href="http://dev.technikum29.de/projects/export/head/projects/punch-card-project/trunk/protocols/documation-m200/protocol.htm" class="go">PC Documation M200 µC Serial Communication Protocol</a> that defines the
132way how computer and microcontroller shall communicate autonomously. It defines, that
133two punch card columns shall be packed into three octetts, each. This binary format has
134been proposed by the computer sciencist <a href="http://www.cs.uiowa.edu/~jones/">Douglas
135W. Jones</a>.
136<br/>For the computer side, we wrote the <i>Punch Card Editor</i>, a program that recieves
137the punch cards from the microcontroller (via the RS232 interface) and visualizes them in
138the graphical user interface. At this step, the text encodings (IBM H9 code, Bull Code)
139can be used to translate between binary punch card data and ASCII text. Thus card decks
140can be read in, modified and saved as files. Of course the comfortable program already
141has the interface for punching paper tapes, once we have selected a device and programmed
142some microcontroller for that job. At this point, there is also another benefit of this
143approach: The program runs on all modern platforms/operating systems (like Microsoft
144Windows, GNU/Linux, Apple OS X, etc. - there just needs to be some RS232 or USB connection).</p>
145
146<p>You can get further details with a lot of documentation material on the homepage of
147<a class="go" href="http://dev.technikum29.de/projects/wiki/PunchCardProject"
148>The Punch Card Project</a>. The source code was released as open source can be checked
149out from the <a
150href="http://dev.technikum29.de/projects/browser/projects/punch-card-project/trunk">technikum29.de
151subversion repository</a>.</p>
152
153<!--  irgendwie schon sinnlos, auf ein deutsches PDF zu verlinken:
154<br/>We've published a german paper <a href="http://dev.technikum29.de/projects/wiki/Papers"
155>Lochkartenverarbeitung per Computer</a> (30 pages)
156with an analysis of the problem, modelling and implementation on both microcontroller
157and Computer (there won't be an english translation).</p>
158-->
159
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