Bombs away!

If a customer sent us a disk with drilling hole data this made our job easy, but many times they only sent us artwork on film, or worse. In this case it was up to Daniel Donoso (a very nice guy from Chile) to digitize all the drilling locations for a board. You take a different color permanent magic marker for each hole size, and then you connect the dots making a track that leads through all the drilling positions.

Then you place the artwork on a large digitizing machine called an OPIC II made by Excellon. This had a large polished granite platform, and on top rested a platform on top of felt pads. The artwork is placed on the table, and then using two control wheels the table is moved with several decimal places of precision through the course laid out in marker. Daniel would sit and peer into a "bombsight" down at the table and drop imaginary bombs on each position with a foot pedal. Each time he did this the X and Y position of the table was recorded to paper tape. This could take a while to do, and it took practice.

One really cool thing about the OPIC II was the digital display for showing the X, Y coordinates. It didn't have an LED display. Instead each digit position had one of those little vacuum tubes that had incandescent filaments shaped like each digit. I guess this might have been a plasma display, and not incandescent, I'm not sure. If you looked carefully you saw that the different digits were not all the same exact distance from your eyes because they were all packed into the tube in a row, one behind the other.

The OPIC II could not be called a computer, but later on we would find a way to use a computer with this machine.

Paper Tape

When there was a mistake in a long CNC program, sometimes it was easy to tell that it was a mistake at the beginning of the program. Rather than read the whole thing in, edit it in WordStar and then punch a whole new tape, sometimes it was easier to repair the paper tape itself.

Usually you could just create a new section of paper tape, and then you unroll the tape to the section you are looking for and splice in the change. With some practice it wasn't too hard to read the binary numbers by eye. Instead of ASCII values, CNC programs were punched to tape using EIA (Electronic Industries Association) codes.

In some instances if you didn't need to change the number of characters, but just which values (change some digits for example), you could just cover the holes with tape and punch new holes. I think I did that at least a couple of times.

So, this all seems very archaic right? On the plus side you really had control over the stored data. Today if your disk drive or your flash memory loses a bit you can't even see it let alone fix it. ;-)

Welcome to the Machine

Or welcome to the machines as it were. I think there were four Excellon drilling and routing machines at C.F.C. One of them had just a single head and was used for making first pieces to test for errors in the drilling and routing programs.

So my first job was to learn the programming language for these machines. Bob Spain and a young lady named Kristen Van der Laan were my teachers. This is no high level programming language, but more like a machine code of sorts. Circuitboards are still drilled and routed this way today more than 20 years later.

Here is an example of a very short Excellon drilling program. The actual language for CNC machining is based on commands used to control Gerber Scientific plotters:

M48
T1C0.028
T2C0.032
%
M48
G05
M60
T1
X2.550Y1.550
T2
X2.600Y1.650
X2.600Y1.750
M30

That drills just three holes of two different sizes. Writing programs to drill holes wasn't really the engineer's job. We mostly wrote programs to cut the boards out. Most of these were simple rectangles, and the program for this wasn't much longer than the example above. Sometimes boards would be circular, or have odd shapes. Some would have chamfers, fingers, slots, large inner cutouts. There was great variety. Sometimes we would make palletized panels which have more than one circuitboard. The routing was designed to leave only small perforated spots to hold it all together, and the boards would be removed from the panel either by hand or by machine.

We would write a program for routing using WordStar and then save it to a floppy disk. Then we would send the program out to the paper tape punch machine. The tape was usually gray, blue or pink. There were little tiny round pieces of colored paper all over the place.

A finished program would go out for a first piece to make sure it was correct. If you left just one digit out of a routing program the machine could destroy the panel, cutting straight through the middle of it.

A Cornucopia of Computers

So I joined the engineering group at C.F.C. Our job was to write and debug CNC programs for the Excellon drilling and routing machines. Most of the programs were written using WordStar on Osborne-1 and Kaypro CP/M machines. We did not use hard drives to do this work, and the final medium of storage was punched paper tape. Yes, really! That was the format the machines used, and we had a storage library for keeping the tapes.

There was one Macintosh in engineering for special purposes, but here again I never used it.

There was a TRS-80 used for managing job tracking in the factory. It had the standard silver expansion box and three floppy drives.

Accounting had an Epson PC clone (or was it a Leading Edge Model D?), and there were a couple of Tandy Model 100 laptops that look like Alan Kay's Dynabook prototype.

Things were about to get interesting.