Chapter 4: Micro Chroma 68 Lives!
I held off until the last weekend in January, to be sure I had enough money for the gas to Austin and the keyboard, and a bit extra for a few other things I could only guess at before I got there.Friday the 30th, after classes, I got the timing light out and tuned the engine of the family station wagon, a 1971 model Mitsubishi-made Dodge Colt, and headed out. In Japan, the model type is called "light van", but you'd probably recognize it as a compact station wagon. It had a five-on-the-floor manual transmission, and the Mitsubishi engine was really fun to drive. But the heater didn't work, and the aging engine had to be tuned regularly.
We had weather warnings for a cold snap, and the temperature headed down as I drove past Midland and turned south, plummeting as I drove through Big Spring and Sterling City. I stopped after Sterling City to get my sleeping bag out and wrap my legs in it.
The sleeping bag helped as far as the by-pass around San Angelo, but I had to leave my legs free enough to operate the gas, and to reach the clutch and brake if there were an emergency. Wall and Eden had speed zones and required dropping to 30 MPH (50 KPH), which is not a fifth gear speed, and both had stops, too. Keeping my legs wrapped there was not possible.
I could not protect my feet from the cold.
I wondered if God were telling me to not to do this, or if He were letting the devil try to stop me. Or if he were just seeing what I would do in bad weather, for grins.
With the wind-chill, it was well below freezing in the car, and my feet were beginning to feel a little frostbitten when I pulled into a motel parking lot in Brady, about an hour and a half, maybe two hours out of Austin. I was losing body heat fast, and had the shivers. It was either pay money for shelter or set up some sort of real camp, and, while I had the sleeping bag, I really wasn't prepared for camping in sub-zero weather.
I had to spend precious money, ten dollars for the night. (What would it be now with inflation, huh?) But the room had a heater, and was warm enough with my sleeping bag over the covers. I called Denny to tell him where I was, and he called Mom and Dad, to save me the cost of the second long distance phone call from the motel.
To keep myself occupied while my body and feet warmed up, I studied the Micro Chroma 68 manual and some of the other datasheets under the covers a bit before I went to sleep. I also got up and plugged the board into the hotel room TV to get a look at the output in color, just for the funstrations. Moving around the warm room helped the circulation.
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| Micro Chroma 68 Monitor ROM Boot ScreenColor |
It felt strange to see the monitor prompt me, and to not be able to type commands.
Frustrations helped warm me up that night.
The real temperature got down below zero Fahrenheit (below -20 Celsius) during the night, and then warmed up enough to snow by six o'clock, when I woke up. But the clouds had broken, and the sun was warm when it rose a bit before seven. I had a bit of tailwind, the roads were clear enough to drive at half-speed until the passing of cars melted and scattered the snow, and the car and I were okay for the rest of the trip. By the time I got to Austin, the streets there were completely clear of snow.
Denny had some chores to finish for Denise, so I checked his wiring while I waited. And I looked over the heavy-duty voltage regulators he had gotten for the power supplies and the three millimeter aluminum plating he had gotten for heatsinks.
When he finished his chores, he got out his drill and router, and we cut and drilled the heatsink plates and mounted the voltage regulators and wired up the improved power supplies, and then we checked his board.
It didn't boot, but we found the problem quickly. He had done some soldering late at night and left a solder bridge across a couple of the ROM socket address pins.
Then we looked at the Micro Chroma 68's diagrams and code again, to get as good an idea as possible of what we would be looking for at the surplus shop.
After that, we went out and both crawled under his Fairlane coup, and we spent an hour replacing the transmission, talking about what we would need for the computers while we worked. When we had the replacement tranny installed, we test-drove it around the block. Finally, we cleaned up and drove the car to the surplus shop, for a longer test drive.
Denise was happy to send us on our way, glad to have two cars running again.
John Phillips, the proprietor of the surplus shop, was a former employee at Motorola, and another friend of Denny's.
"Keyboards are all in these bins and on these shelves over here."
"Documentation?"
"What you see is what you get."
None of the keyboards had any documentation.
"I like this keyboard." Denny held up one.
"104 keys. Kind of big. Microcontroller controlled." I gave him a lop-sided frown.
"That keyboard does not produce ASCII codes," John commented. He didn't have documentation, but he had the necessary information.
"So it would require some serious customization, like programming our own controller."
"Guess we'd better pass on this one." He put it down. "Here's one with no controller at all."
"So we'll have to add a ROM for decoding the keyboard, and patch the monitor ROM to call it. Do you have an EPROM burner?"
"Guess not, not yet. That's something we have to build."
"Yep."
"Hmm. Maybe put some LSI latches and shift registers on a perfboard? Oh. Here's a Cherry."
"Nice. but I was hoping to leave a little money for other things."
"Yeah, Den won't like that price. Here's a 56 key keyboard with some simple LSI."
"I like the layout. But there're no cursor keys."
John commented again, "That one puts out 7 bit ASCII with a negative going strobe. They were extras left over from a teletype machine production run. Pretty much like a Cherry keyboard."
"BINGO. Price is good. Do you have two?"
"Yep." John rummaged around in the bin, and pulled out two still in bubble-wrap.
We picked up the keyboards and took them to the counter, then went wandering around some more.
"Here's a ten-key pad with cursor keys." I picked it up and showed Denny.
"Do we need it?"
"I think I'll want it. Cursor keys, as much as the numeric pad."
Denny picked one up and looked it over. "Price is not too steep. Maybe I should get one, too."
"Oh, and here are the zero insertion force sockets for the EPROM programmers we need to make."
"ZIF. 28 pins?"
I checked. "24, 28, and 40 pin."
"We should be able to do 24 pin ROMs with the 28 pin socket. Snag me one of the 28 pin sockets."
"I'm going to get the 40 pin socket, too, for programming 68701s."
"Good idea. Get me one, too."
I picked up the sockets.
"Are you interested in EPROM eraser beds?"
"Sure."
John pointed us to another table, and we looked at them.
Denny's forehead wrinkled in a frown. "I'll bet we could make our own for that price."
"Getting the lamp at the right wavelength is the problem."
"Hmm."
"That stop at the motel last night leaves me short of the price. Maybe next time."
"How much short?"
"Ten bucks."
"I can take that off."
I scratched the stubble on my chin. "Cutting it too close on my budget. I'll take my chances that you'll have one the next time we come."
Denny chuckled. "Oh! Silly scope!"
John laughed.
"Our dad's pun."
"I see."
"A hundred dollars is not bad, but I don't have that much. And it only goes to 1 megahertz. We need ten megahertz minimum."
John showed us a couple of hundred megahertz capable scopes, but they were way beyond our financial resources. I wrote the prices down, anyway.
"Tape drives." Denny lifted one for inspection.
"Cool. Not this time around, though."
"Actual data cassette drive." He looked at the price tag. "Ouch. Definitely. That's too rich, too."
"I can give it to you for half that price."
Denny shook his head regretfully. "Still more than either of us can afford."
"Yeah, and if I had that much, I'd want a floppy drive, instead."
"We have some floppy drives over here." John showed us another set of shelves.
We looked at the drives. "Chassis, motors, screw gear and head assembly, no electronics besides the head."
"Yeah, there's too much we'd have to develop ourselves, and no tools yet to do it with. Need the scope to align it. But a nice price if we had the tools and the time."
"I'd have the money if I hadn't had to stop at the motel last night."
"That's the best you're going to find, at least this year."
Denny shoved his lower lip to the left in thought. "Dean Brougham has that high speed tape design he was telling me about."
I set my jaw to the right. "I guess it would give us some practice with extracting data, in addition to faster persistent store?"
John nodded. "The encoding and modulation won't be the same, but it would give you something to store programs and data on and share them. I must admit, I'm not sure I'd be able to get one of these to work."
We stopped at the UT campus on the way home, and I picked up course catalogs and other materials.
Back at the house, Denny told me to dig out a record to put on the stereo while we worked.
"Deep Purple? Since when were you into hard rock?"
"Thought it was something else. Den kind of likes 'Hush', though."
"No, you do." Denise laughed.
"Heh. Sometimes. But I can't handle listening to the whole album."
"Thinking of the 'Deep Purple Dream' cover by Stevens and Tempo?" I sang a few lines and hummed a few bars.
"That's one I like," Denise gave Denny a significant look.
"But it's not what I was looking for. I thought I bought this for 'Hush'."
"How about Herman's Hermits cover of 'A Kind of Hush'? Or maybe the Carpenters' cover?"
"Dang, that sounds like it might be it."
I sang a few lines of that, too.
"Write those down for me. When we get some extra money, I'll get them for Denise for her birthday or Christmas."
"Promises, promises." Denise smiled wryly, and I quietly promised myself to save up some money for the records.
(In the real world, I couldn't drag the names of either song out of my memory at the time, and it was a long time before I was able to spare any money for music again, even though I had bought some hundred or so albums of various genre before my mission. Before my mission, I would have copied some of my albums to cassette tapes for them. After my mission, I was more careful of copyright.)
Over the course of the afternoon and evening, we got the keyboards working and used a voltmeter for rough-tuning the Kansas City Interface circuitry so that we could fairly reliably read program tapes Denny had from his friends, and we could read and write programs and data from each others' boards.
"Don't want to take the assembler and editor programs back with you?" Denny held up a cassette tape.
I shook my head. "No, not really."
"I could burn them into a ROM for you at work."
"It's the copyright."
"How are you supposed to know if you want to buy it without test driving it?"
"Next time, maybe. I think I have plenty to do. Besides, I want to write my own."
"That's crazy talk."
"Everything I let someone else write for me is more software I can't really trust."
"Do you trust yourself that much?"
"Good point. But at least I should be able to fix it myself if it's something I wrote."
"Maybe."
"Need better options. Especially relative to software you won't be able to get the source code for."
Source code is what the program or program modules (often called "libraries") in human readable form is called. You run a compiler or an assembler on the source code to produce object code that the computer can directly run -- except for interpreted languages like many versions of BASIC, which have an text-level interpreter instead of a compiler, and the interpreter reads, interprets, and runs the source code directly.
"So, you'll only run stuff you write yourself, or stuff you get the source code for, as well?"
"Case-by-case, but I'm also pretty sure paying for the software gives me a better chance of getting the bugs fixed."
"Good point."
I went to the University of Texas student ward on Sunday, to meet people and see if I liked it. It was okay.
I checked over the UT catalog with Denny before I left.
"See, they have Japanese courses."
I read the descriptions. "I think it'll be repeat for me, but I'll think about it."
Denny shrugged and rolled his head back and forth on his neck. "If you're going to be that picky, it's going to be either BYU or Berkeley for you."
"Dad said he does not want me going to Berkeley."
"Cutting edge research in computers."
"Yeah." I raised my eyebrows and sighed. "I am considering Berkeley, too. You know, I'm thinking I should make a box for this computer before I start taking it to school."
"It's a good idea. What do you have in mind?"
"You saw the tea box I brought home from Japan?"
"The one you put all your albums in?"
"Yeah." My record album collection pretty much filled the tea box.
He grinned. "Metal lined. But it's a little on the big side for this computer, I think."
"True. I'm thinking of building a box shaped like a typewriter and lining it with sheet metal, like the tea box."
"Might work."
Before I left, Denny handed me a rail of 64 kilobit RAM chips with a broad grin. "Think you can figure out how to use these?"
I grinned back happily. "Tested from the recycle bin?"
"Yep."
"I definitely think I can figure it out."
When I got home, a letter from Satomi was waiting for me. She informed me she was engaged to an older returned missionary I had met once in Niigata on trade-offs, one Brother Fukumasa. I sat down and wrote a reply congratulating her and Brother Fukumasa, and realized I needed to think more seriously about going back to Japan.
[Most recent backup at https://joel-rees-economics.blogspot.com/2020/01/bk01-33209-micro-chroma-68-lives.html.
First backup at https://joel-rees-economics.blogspot.com/2020/01/bk-33209-micro-chroma-68-lives.html.]
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