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AutoCAD

In the Beginning (Learning Curve AutoCAD Tutorial)

31 Dec, 2006 By: Bill Fane

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A 20-year retrospective reveals the evolution of CAD software and hardware.

Once upon a time, way back in the last millennium, a relatively new AutoCAD user went to a VAUS (Vancouver AutoCAD Users Society) meeting. Actually, in those days, everyone was a new user, for this was in the time of v2.17g, and VAUS was the first AutoCAD user group in the world. Its founder, Lionel Johnston, had just split its newsletter off and made a separate commercial magazine out of it. You may have heard of it; it's called Cadalyst.

The new user had figured out a solution to the problem of drawing scales, and had given a talk about his discovery. After the meeting, Lionel approached our protagonist and said that he would like to publish the handout that had accompanied the talk. A month later, Lionel called to ask if the user wanted to write a regular column. And so it came to pass that "The Learning Curve," and hence Captain LearnCurve, came into existence. Okay, enough of the pleasant reminiscences. Let's get on with business and fast-forward to the present time.

It was a dark and stormy January morning. The Captain walked into class for the first day of the new school term and suddenly realized that his first Learning Curve column was older than most of his current students. Ouch.

Oh, to heck with it; let's go back to the pleasant reminiscences. My grandmother used to say that anyone who longed for the good old days never lived back then. In most respects she was right, but there are still a few "good old days" aspects of computers that I miss, as you'll see later.

Ladies and gentlemen, welcome to the 20th Anniversary edition of "The Learning Curve!" This is number 178 in an ongoing series. Be the first on your block to collect the complete set.

Setting the Stage
By 1986, I had already been working as a doorknob designer for the Canadian facility of Weiser Lock for 18 years. We had decided to investigate the various CAD systems on the market, most of which ran on a dedicated engineering workstation and would set us back more than $200,000. Several magazine articles on how to choose a CAD system all said "Decide what your needs are, then find a system whose capabilities match those needs."

Yeah, right, that sounds good -- but how do you do that when you've never used CAD, and therefore don't know what questions to ask?

We decided to take an interim step. We would buy one copy of the "Etch-A-Sketch" system, as the big boys disdainfully referred to AutoCAD, in order to acquaint ourselves with the basic principles before moving on to the good stuff.

Twenty years later, Autodesk is the big boy, and pretty much everything else we looked at in 1986 is gone. Okay, let's talk about our first CAD system.

How Hard Is Your Hardware?
Our first AutoCAD station turned the rest of VAUS green with envy. In those days, AutoCAD would run (okay, it would walk) on a 4.77MHz XT with a single floppy drive and 512K of RAM. Luxury was a second floppy so you didn't have to keep swapping the disk that contained the overlay files in and out as you switched between commands. Real luxury was having a joystick instead of using the keyboard arrows to move the cursor, and a full 640K of RAM. The standard graphics setup was either a Hercules monochrome card at 720X350 resolution, or a CGA card at 320X200 in four colors (one of which was the black background), and a 12" monitor.

We were one of the first in town to get one of the new powerhouse IBM AT 286 machines. It ran at the breathtaking speed of 6MHz. Better than that, the new machines used separate clock circuits for the CPU and the graphics, so we were able to "crystallize" our machine. Dealers would carry a rack of quartz crystals of ever-increasing frequencies. We would unplug the 6MHz crystal, plug in a 6.5, and run the machine for a while. If it still worked then we would take the speed up a notch, repeating the process until it crashed or made mistakes, at which point we would back up one step.

We would then return the rack of crystals to the dealer, paying for the one we kept. He would reload the rack and pass it on to the next customer. We eventually had ours running at 10.5MHz.

It had 640K of base RAM, plus we paid an extra $1,300 to get 1MB (yes, that's one megabyte) of extended memory. We had a Tecmar Graphics Master video card with 640X480 resolution in 16 colors (yep, count 'em; we actually had 16 colors!), connected to a 19" monitor.

Super-luxury: we had a 20MB hard drive, and an optional math coprocessor chip!

The complete system, including a 24"-wide pen plotter and a digitizer tablet, came to just over $10,000 in 1986 dollars.

The plotter was the hardest thing to get running. It seems that IBM figured the original PCs were going to be used as terminals on a mainframe computer, so their serial ports were wired as peripherals, not as source devices. The problem was that plotters were too, so part of the installation kit included a soldering gun so we could fabricate our own crossover connecting cable.

Very Soft Software
Before you complain about annual software updates, contemplate this fact. When we placed our order, it stated AutoCAD v2.17e. By the time it was delivered two weeks later, we received v2.17g. Even better, one bug fix arrived in the form of a set of instructions on how to use a DOS utility program called DEBUG.EXE to go in and manually patch some of the hexadecimal code in ACAD.EXE.

In the "good old days," AutoCAD had no toolbars, palettes or menu bar. Commands were selected from calibrated regions of the digitizer tablet or from the "screen menu." If you want to try using this latter feature in any current release, select Tools / Options, click on the Display tab and then select Display Screen Menu. Here are a couple of hints: Selecting AutoCAD will always return you to the root menu, and the row of four asterisks (****) invokes the object snap override menu.

The earlier releases did not have Undo. We used Save a lot before making any significant changes. When things crashed, AutoCAD asked, "AutoCAD cannot continue. Do you want to save your changes?" It turns out that all it was doing was conducting an opinion survey; I never did see it actually save a drawing at this point.

Every pan and zoom invoked a regen. There was no transparent zoom and pan, although enterprising programmers were able to fake a pretty good approximation using the newly introduced AutoLISP programming language.

The DOS operating system did not support multitasking, but AutoCAD was unique in allowing you to Shell out and run another DOS program from within itself. By the way, this command still works. Enter the Shell command, and when AutoCAD asks for an OS Command, simply press Enter. You are now in a DOS shell within AutoCAD. Yours truly used this latter feature to fake a spell-check command. When invoked, it would use AutoLISP to select all the text in a drawing, and then use the Dxfout command to write it out in a DXF file. It would then Shell out to DOS and run WordPerfect with a macro that ran its spell checker. When you were finished, it would delete all the selected text from the drawing, and then replace it by using the Dxfin command on the repaired DXF file.

Hatching was an adventure in its own right. The hatch boundary had to be defined by manually selecting a series of lines, arcs and polylines that formed a single, contiguous boundary. If there were any gaps or overlaps at any of the intersections then the hatching might leak out and attempt to hatch the known universe, or it might skip over and omit some hatch lines.

There was no paper space, and hence no layouts. 3D was very minimal. Objects could be given an elevation and a z-direction thickness, but there were no curved or 3D faces or sloping lines. Both ends of a line had to have the same z coordinate, and all arcs and circles had to lie parallel to the x,y plane. There were no User Coordinate Systems. Nonetheless, one enterprising individual built an incredibly detailed model of St. Paul's Cathedral, which was supplied with AutoCAD as a sample drawing.

Do You Remember...
Computer memory was very limited, and almost everything, including the operating system, had to fit within 640K of RAM. The AT series of computers introduced "extended memory" that could be used to hold your drawing data, but no programs. With a big program such as AutoCAD, memory was so scarce that a hue and cry went up when DOS went from using 55K of RAM to needing 77K. By comparison, Windows XT Pro gets pretty close to using 1GB before you even start an application!

Each program or device driver had to fit within a single contiguous block of memory. Enterprising programmers soon figured out that there were several chunks of memory in the range between 640K and 1MB that weren't being used unless you were using a CGA graphics card, and they developed memory management software that let users load small device drivers (such as mouse and plotter drivers) into those gaps, thus freeing up more precious lower-level memory.

The Good News
We knew exactly which programs and drivers were running where and when. There were only two ways of loading a program automatically. Device drivers were listed in and invoked from a simple text file called CONFIG.SYS, and application programs such as AutoCAD could be invoked from AUTOEXEC.BAT. Compare that with Windows XP; does anyone know for sure how many ways there are of loading things when a computer boots up? My laptop currently has 76 processes running, and all I am using is Word and AutoCAD. Where did the others come from, and what do they do? No wonder we have virus problems.

Our old AT would go from a power-on cold boot to the AutoCAD Command prompt in less than 30 seconds. Better than that, I still have an old Toshiba T1000, which according to http://biphome.spray.se/baxtrom/t1000/ was the very first true laptop. Its graphics are text-only so it wouldn't run AutoCAD, but DOS is built into a PROM chip and there is 756K of RAM in a battery-sustained virtual drive. From power-on to using WordPerfect takes less than five seconds. Today, my 3GHz dual-core desktop machine takes nearly four minutes to get from a cold boot to the AutoCAD Command prompt.

Maybe the good old days weren't so bad after all.

Mushware
We later updated to a 1024X768 graphics card (actually, it was a piggyback arrangement that occupied two expansion slots) with 256 colors. It failed under warranty. When it came back, they had updated the board's BIOS chip. The new driver software was now so large that there was no room to install the mouse or plotter drivers, so AutoCAD was essentially useless (this was in the days before memory manager software). The old driver wouldn't work with the new BIOS, and the company went bankrupt about the same time. We ended up throwing away a 10-month-old $1,300 graphics card.

Maybe the good old days weren't so good after all.

On the Other Hand
Despite my seemingly disparaging remarks about the past, don't forget that there would be no present without the past, and that those early CAD systems were still a lot better than pencil and paper. I've been known to spend several days doing nothing but manually hatching a cross section of a complex assembly on paper.

But on the other other hand, the Boeing 747 and the moon rockets were designed with paper and pencil. How's that new monster Airbus coming, by comparison? There seem to be wiring problems stemming from management of the CAD systems?

And Now for Something Completely Different
When you are vacationing on Maui, it is traditional to blow a conch (pronounced "conk") shell horn at sunset. If you wish to join in, do not eat salted nuts or other salted munchies beforehand, or you will not be able to pucker properly to get your horn to work.