[JMR202001161222: Backup]
Chapter 3: School
Chapter 4: Micro Chroma 68 Lives!
It took me until the last weekend in January before I had saved enough money for the gas to Austin and for the projected purchases.
I took off Friday after classes in the family Dodge Colt compact station wagon. It had a five-on-the-floor manual transmission, and was fun to drive. But the heater didn't work, and the engine had to be tuned regularly. I got out the timing light and gave it a tune-up before I left.
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.
It was cold, and I could not protect my feet.
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 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 sub-zero weather.
I had to spend precious money, ten dollars for the night. (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 a bit before I went to sleep. I also plugged the board into the hotel room TV and got a look at the output in color, just for the funstrations. Moving around the warm room helped the circulation, but it felt strange to see the monitor prompt me and not be able to type commands.
Frustrations helped me warm me up that night.
It got down below zero Fahrenheit (below -20 Celsius) during the night, and there was snow on the ground at six o'clock, when I woke up. But the clouds had broken, the sun was warm when it came up a bit before seven. I had a bit of tailwind, the roads were clear enough to drive at half speed until the passing cars melted and scattered the snow, and the car was 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 heavier 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 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."
"104 keys. Kind of big. Microcontroller controlled."
"That keyboard does not produce ASCII codes," John commented. He didn't have documentation, but he had the necessary information.
"That would require some serious customization, like programming our own controller."
"Guess not. 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 52 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. Pretty much like a Cherry keyboard."
"BINGO. Price is good. Do they have two?"
"Yep."
We picked up two 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."
Denny picked one up and looked it over. "Price is not too steep. Maybe I should get one, too."
"Oh, here Zif sockets for the EPROM programmers we need to make."
"28 pins?"
I checked. "24, 28, and 40 pin."
"We should be able to do 24 with the 28 pin one. Snag me one."
"I'm going to get the 40 pin socket, too, for programming 68701s."
"Good idea. Get me one, too."
I picked up the sockets.
"Oh Silly scope!"
John laughed.
"Our dad's pun."
"Oh."
"Two 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.
"Reel-to-reel tape drives."
"Cool. Not this time around, though."
"Definitely. Data cassette drive. Ouch. That's too rich, too."
"I can give it to you for half that price."
"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, 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 a 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 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. I didn't know about the BASIC interpreter's provenance and copyright status, but I didn't want to use too much of the software that my brother's friends were using without paying for it.)
Over the course of the day, we got the keyboards working and tuned the existing slow cassette 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.
I went to the University of Texas student ward on Sunday, to meet people and see if I liked it.
Before I headed home, we talked about building boxes to mount the Micro Chroma 68 boards in, and I mentioned the sheet-metal lined tea box. Denny grinned and said it would be too big for this project. I had to agree.
And Denny handed me a rail of 64 kilobit RAM chips. "Think you can figure out how to use these?"
"I'll work it out."
When I got home, a letter from Satomi was waiting for me. She informed me she was engaged to a returned missionary I had met on trade-offs, one Brother Fukumasa. I sat down to write a reply congratulating her, and realized I needed to think seriously about going back to Japan.
Chapter 5: Summer Interning
[Backed up at https://joel-rees-economics.blogspot.com/2020/01/bk-33209-micro-chroma-68-lives.html.]
[JMR202001161222: End.]
No comments:
Post a Comment
Keep it on topic, and be patient with the moderator. I have other things to do, too, you know.