Car Repair

Voice Card  -  Volume 21  -  Paul Card Number 9  -  Wed, Sep 11, 1991 4:27 PM

[Editor's note: This card, and the card which follows it, were transmitted by Paul via AOL shortly before this issue was launched.]

{contributed by David A. Moon to Desperado #3052}


By John Wharton

The story you are about to read is true. Identities have been concealed to protect the enterprising. Those of us who design and build microcomputers usually think we have a pretty good idea of our target markets and who the potential users may be. We're usually wrong. If a product succeeds in the marketplace, its eventual uses will extend far beyond the horizon foreseen during product definition.

Consider the following bizarre tale. I was driving to a friend's wedding in southern California one snowy Saturday morning, already running late, when a cloud of greasy smoke erupted from my dashboard. I soon found myself in Tehachapi, CA (population 4,126) desperately seeking a mechanic.

The third garage I came to looked open, so l knocked on the door and went in. Just inside stood two coverall-clad mechanics who seemed to be anxiously waiting for someone. They eyed my wedding garb suspiciously, and I felt like I'd stumbled into a Miami Vice drug buy, but after a while the older mechanic spoke up. "Did you bring the PROMs?" he asked.

A very strange question, coming from a car mechanic, but I was in a rush.

"No," I answered, "I'm afraid all I've got is a broken-down Toyota, and a desperate need to get going again as soon as possible."

The mechanics asked about the car's failure mode, maintenance history, anti-freeze level, and so forth, to which my answers merely showed how poorly I understood how cars work. I design computers for a living, but automobile engines are black magic.

After realizing I'd be of no help at all, the mechanics began poking under the hood, pressurizing the radiator, tracing the path of the cooling-system hoses, unplugging connectors, and testing for leaks. I was struck by how his actions resembled a computer designer debugging a giant, grease-encrusted breadboard. The Master Mechanic concluded I had blown the heater oore in the dashboard, for which the quickest fix would be to "short-circuit the core with a bypass hose, which would hold me until the core could be replaced. The computer industry is not the only one with garage-shop hackers, I thought.


Now, Tehachapi is chiefly a bedroom community for test pilots from Edwards Air Force Base, hardly a hotbed of computer system design, so the Mechanic's earlier question about PROMs had come as a surpise. While his partner hacked away at the heater I/O hoses (literally, with a knife), I asked the Master Mechanic what (in his business) the word PROM meant.

"Oh, that," he replied. "PROMs are how microcomputers store programs. We're rebuilding the engine computer in that Taurus over there."

Great, I thought. Here was a topic I could relate to! "I didn't know engine computers could be fixed," I said. "I thought you had to replace the whole assembly." "Used to, you did," the Mechanic replied. "Everything was soldered down and potted in resin, but no more. If you can get the box open, you can swap chips until it works. It's a lot cheaper than junking the whole board. Everything's in Augat sockets now," he said, showing me an open module.

Augat sockets! It had been ages since I'd heard hardware engineers sing the praises of Augat sockets, certainly not what I'd expect here. The only engineering circles in which Tehachapi is famous are of the railroad variety, thanks to the Tehachapi Loop, an unusual switchback in the tracks through a local mountain pass. The conversation had taken an unusual turn, but at least now I could show off my computer expertise and soothe the battered ego I'd suffered from being so helpless under the hood.

"I actually design computers like that, up in Silicon Valley," I began. "In fact, I developed Ford's very first engine computer, back in the `70s." That should impress him, I thought.

He pondered briefly, then asked: "EEC-3 or -4?" Damn! This guy was good. "I thought it was EEC-1," I began, trying to remember the "electronic engine control" designators. "It was the first time a computer..." "Nah, EEC-1 and -2 used discrete parts," he interrupted. "EEC-3 was the first with a microprocessor." "That was it, then. It had an off-the-shelf 8048."

"You mean you designed EEC-3?" the Master Mechanic asked incredulously. "Hey, George!" he shouted to the guy working under the hood. "When you're done fixing this guys car, push it out back and torch it! He designed EEC-3!"

So much for impressing the Mechanic, huh? I shot back defensively. "Did EEC-3 have a problem?" "Reliability, mostly," he replied. "The 02-sensor brackets could break, and the connectors corroded."

I beat a hasty retreat. "Those sound like hardware problems," I said. "All I did was the software." "EEC-4 was much better," the Mechanic continued, gazing wistfully into the distance, as though thinking back to his first `57 Chevy. "Now there was an engine computer. Sixteen-bit CPU, fuel injection, timing, spark advance... Boy, that EEC-4 could do anything!"

"I should hope so," I responded. "Intel designed its CPU just for engine control. Later they repackaged it called it the 8096. Still sells pretty well, too." Common ground at last!

"Yeah, it was EEC-4 that really sold me on Intel," the Mechanic continued. "Made me scrap my AT motherboard and put in a genuine Intel 386 version. Tried a turbo card first, but it just couldn't hack it."

(Note to Intel marketing strategists: you might as well scrap your Business Week ads: the real grass-roots buyers read Road and Track. How about a promo with a monster truck crushing a row of Motorola processors, with the catch-line, "The Computer Inside"?)


"Say, you know anything about the 387?" "Sure," I answered, confidently. I'd written several articles and two manuals on 386-family products. Data formats, FPU instructions, I knew it all, I thought.

"What's the difference between a 387-2 and a 387-10? I had my system's hard disk upgraded, and when it came back from the shop my spreadsheets wouldn't run. I think the technician switched coprocessors on me.

"Sorry," I said. "I never studied the different steppings, or speeds, or binnings, or whatever."

"How about the BIOS?" he tried again. "Could new BIOS PROMs make an application stop running?" "I've no idea," I replied, again feeling unredeemed "but frankly, with DOS I wouldn't be surprised by anything that broke if the BIOS was changed." "Well, can you at least tell me where you buy DRAMs, and what's a good price?"

Finally! A question I knew I could answer! "I get mine at Fry's," I said. "They're down to $49 for mega- byte-by-nine SIMMs." I started describing the Fry's supermarket chain, a local curiosity that stocks the valley's best assortment of software, microchips, and Freon alongside soft drinks, potato chips, and deodor- ant, but the Master Mechanic wasn't amused.

"That's too small. My board's already stuffed with one-megs. I need four-meg SIMMs now." Strike three. Now it was my turn to be incredulous.

"What do you do with your PC, anyway?" I asked. One-meg SIMMs had always been enough for me. "Oh, PROM burning, data acquisition, DSP, that kinda stuff. Just got a new 16-bit A/D and D/A add-in board for analog work. Use it to check out connector voltages, to see if the engine electronics is working. Hey! Wanna see my new HP oscilloscope?" he offered. "Four traces, 100-MHz."

I declined. I'd thought car mechanics only used scopes to check ignition timing. "I'm thinking of getting a logic analyzer," the Mechanic continued. "You build computers, you must know something about logic analyzers. What kind should I get?" (I *swear* I'm not making this up.)

"Logic analyzers?" I said, counting the years since I'd last touched a logic analyzer. "Yeah, sure, logic analyzers are good..."

The conversation had crossed into the surreal. Suddenly it dawned on me why these guys were working on a weekend. "You know," I said, "back when I was working on EEC-3, my boss said I should keep a copy of the program listings for my records. He predicted someday there'd be an aftermarket for high-performance PROMs that could hop-up the engine by overriding the standard emissions controls and fuel-efficiency algorithms. Do you think that'll happen?"

"Already has," the Master Mechanic replied with a wink. "Sold through the mail, mostly. They'd be illegal, of course, if they failed state emissions standards."

Of course. And just imagine how difficult it must be to reverse engineer an undocumented engine computer. You'd need a PROM burner, a data-acquisition system, and a good scope, for starters. And maybe a logic analyzer... But by then my car was ready, and I had an already-in-progress wedding reception to join. I can only guess the fate of the disassembled Taurus.


There's probably a slew of morals lurking in this story, about not prejudging technical competence based on appearance, and the hazards of trying to impress strangers. Pride doth goeth before a fall. But what struck me most was how these computer-proficient grease monkeys seemed to come straight from today's science-fiction. Cyberpunk novels like John Brunner's Shock wave Rider and William Gibson's Neuromancer often pit computer hackers against a repressive future establishment. Their mastery of technical arcana lets them navigate the interstices of cyberspace, hide from authority, and escape domination. I thought especially of Terry Gilliam's bizarre film Brazil, in which a renegade plumber hacks sewage systems and cooling ducts much the same way George used a bypass hose to short-circuit my heater core.

At first it seemed remarkably incongruous to find self-taught computer engineers fixing cars in a smalltown garage, but in a way it's inevitable. The basic skills needed to diagnose and repair complex systems are the same, whether the underlying technology is gasoline-engine or microprocessor-based. The same kind of personality that souped-up MGs in the past might naturally enjoy souping-up PCs today.

As microelectronics pervades society, the range of engineers who apply the technology will broaden too, as will the range of engineers who adapt it into new, unintended areas. "Hacking" will expand beyond the realm of slightly-disheveled stereotypical nerds to include a much broader cross section of society.