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My First Computer

Posted by Tom on November 6, 2008

Posted in: Technology.

Early in the 1970’s there was an Atari arcade game called something like Tank Battle. One of my friends from work and I would play this game all the time. Finally we realized that it would be cheaper to build our own game than to keep feeding quarters into the bar machines. At about the same time integrated circuit technology was reaching the state where a home-brew computer was feasible. Magazines like BYTE and Dr Dobbs Journal of Computer Calisthenics’s and Orthodontia were loaded with software and hardware projects and ads from vendors selling components. Computer clubs were being formed all across the country.

Through connections at work I was able to get samples of the Intel 8080 microprocessor and the associated support chips. At the same time another friend of mine had acquired an old UNIVAC mainframe computer for just the cost of hauling it away. Once he had it, he found out that wiring his garage for the required 3-phase power would be prohibitively expensive. As a consequence he was selling off the machine for parts.

With this, the great “Home Computer” project started. Little did I know what I would have to learn and how long it would take to complete. I plugged away and by early 1977 I had built the computer shown below — and it actually worked!

The computer itself was comprised of around 20 hand-made circuit boards housed in a box built from aluminum angle and surplus aluminum sheet. The keyboard was salvaged from one of the keypunch machines from the old UNIVAC mainframe. The monitor was a surplus 9″ display bought from a mail order house. Eventually I built a case for the monitor and “prettied up” the whole rig.

This machine ended up with a whopping 15 kilobytes of RAM and 1 kilobyte of UV Erasable ROM and it operated at a screaming 2MHz clock rate! Two regular cassette tape recorders provided “mass storage” via something called the Kansas City Standard interface. Later this would be replaced with two 5-1/4″ Shugart floppy drives.

Eventually I wrote a symbolic assembler for the 8080 machine code, a simple text editor, a basic interpreter and several games (alas, not the Tank Game).

Here is a picture of the interior of the computer.

On the right is the power supply providing ±13V DC and ±19V DC unregulated . I believe the maximum current was 5 amps. On the center of the rear panel you can see the voltage regulators which converted this to ±12 and ±5 volts.

The left and center sections held the PC cards. These all used 44 pin edge connectors, salvaged again from the old UNIVAC mainframe. In this photo you can identify all of the PC cards or card slots (from front to back):

Slots (empty in this photo) for 7 RAM Cards (2kx8 each)
1K ROM + 1K RAM Card
Memory Control Card
CPU Card #1
CPU Card #2
Status Latch Card
Keyboard Encoder
Video Interface Cards #1-4 (based on the TV Typewriter by Don Lancaster.)
The empty connector in the center bay is for the Cassette Interface card.

This was a fun and very educational project and one of the neatest technical things I have ever done. I spent hours wiring and debugging the unit and writing the software. I probably learned more about digital circuit and software design from this project than I ever did at school or on my day job. Another exciting thing was, for a short time, I was one of the very few people who could casually say, “Why yes, I have a computer in my basement.”

My Shortest Blog Post

Posted by Tom on November 3, 2008

Posted in: Uncategorized.

Fall Critters

Posted by Tom on October 19, 2008

Posted in: Around the House.

It’s been an interesting late summer and fall in terms of critters around the house. Along with some old favorites, there were a number of unusual ones that showed themselves, probably due to this years odd weather.

(As always, click on the thumbnail to see a larger image.)

This Eastern Tiger Swallowtail is a common butterfly around here but I’ve always loved their bright colors.

This is a Maple Spanworm Moth. They were very plentiful for a few days and loved to congregate on the siding of our house.

This Angular-winged Katydid was very comfortable posing on the arm of one of our deck chairs.

One cool and damp morning Jan spotted and photographed this salamander in the leaf litter and stones along our fence. I hadn’t seen one of these around here before and was surprised it was so out in the open.

A Preying Mantis (actually a Chinese Mantid) showed itself to Jan who took this nice picture. He hung around for a couple of days and now has vanished.

Random Quote #8

Posted by Tom on October 9, 2008

Posted in: Random Quotes.

“If the same amount of energy that was spent studying the female bosom went into the space program, we would now be operating hot dog stands on the moon.” — D.W.B.

I have no idea who D. W. B. is but I believe he/she is right about this one.

Tucson – Part 3

Posted by Tom on October 8, 2008

Posted in: Technology, Travel.

On our final day in Tucson we went to the Pima Air & Space Museum. This is a wonderful place to visit if you are an aviation fan. There are hundreds of aircraft on display plus you can take an optional trip to the famous 309th Aerospace Maintenance and Regeneration Group (AMARG) “Boneyard”

One of the first aircraft we saw was the impressive SR-71A Blackbird. It’s hard to imagine anything that can fly at 2200+ MPH but, standing next to it, you have to know this plane is Fast!

Next we went outside to see the exhibits there before it got too hot. Here is a picture of the area where fighter aircraft are on display. There were also areas for bombers, transports, tankers, seaplanes and other sorts of aircraft.

Here is a B-52 Stratofortress Bomber first introduced in 1955 and still in active service today. Without actually being there, it is hard to imagine how big one of these is.

Not all of the aircraft are from the US military. Here is a North Korean Mig-15 (built in Poland) used extensively by the enemy in the Korean war.

Here is the incarnation of Air Force One that was used by president Kennedy, a VC-118A Liftmaster (Douglas DC-6). This was the only plane where visitors were allowed to tour the interior.

As it got hotter outside, we went back into the hangars where some beautifully restored WW-II era aircraft were on display. Among them a B-29 and this B24 Liberator.

Also inside was one of the strangest looking aircraft I had ever seen. It’s the Bumble Bee, the worlds smallest piloted aircraft. It has a wingspan of 5′ 6″ and and overall length of 8′ 10″.

We really enjoyed our visit here and would even consider going back again in the future as there were many displays that we didn’t have time to see nor were we able to take the optional trip to the “Boneyard.”

Tucson – Part 2

Posted by Tom on October 7, 2008

Posted in: Travel.

On our second day in Tucson, Jan, Steev, and I went to the Arizona-Sonora Desert Museum . It is a 21 acre museum and zoo housing 300 species of animals and 1200 kinds of plants. Here are a few of the things we saw there.

I’m sorry that I don’t remember the species of this bird. It was interesting to be able to see it close up.

Here is a Gila Monster resting in the shade. It was behind glass as I would not otherwise have gotten this close.

This otter was Steev’s favorite and seemed very playful and active. It was also possible to watch him swimming from below the water level. Here he was watching Steev take his picture from above.

I had never seen a Coati before. This one was quite hard to spot at first but once I figured out where he was I was able to get a good picture.

There were many different kinds of dragonflies on different plants and around the water. Most of them didn’t pose but this pair had their tiny minds ocupied with other business.

I’ve seen butterfly gardens in many different places but this was the first I had seen that was not in an enclosed building. Apparently they are able to select the proper plants that attract the adult butterflies and also provide food for the larva. In this picture there are at least three butterflies easily visible but there were probably a dozen more that were better concealed.

This was a great place to visit, easier than the previous day’s hike and had water available all around. They even had a nice little restaurant and two gift shops. If you are ever in Tucson, it’s worth a visit.

Root Canal

Posted by Tom on October 6, 2008

Posted in: Around the House.

Today I had what was possibly the longest dental procedure in my life! Two and a half hours in the chair. The pain was not too bad except for holding my mouth open for that long. Novacaine hasn’t worn off yet and I don’t know how it will feel when it does. At least the bad part is over. What remains is the expensive part (crown).

Tucson – Part 1

Posted by Tom on October 1, 2008

Posted in: Travel.

Last week Jan and I flew to Arizona to visit my son, Steev and his fiancee in Tucson. While we were there we did a lot of things so I will be posting about it in several parts.

On our first full day we went to hike in Sabino and Bear canyons In the Santa Catalina mountains which were conveniently located N.E. of Tucson. We got there fairly early but it was already getting hot by the time we were on the trail. Here is Steev and Greta as we started out.

The terrain is fairly rugged, dominated by cactus and other desert flora. Since it was just after the annual monsoon, the plants were quite green and many were in bloom.

There was also quite a bit of wildlife around, mostly birds and lizards such as this little guy who posed very patiently for us.

Here is a shot of the ubiquitous Saguaro Cactus. Some of them are huge – I’d guess 30 feet tall or more.

Not all of the canyon is sand and cactus. We came across this idyllic spot along Sabino Creek.

Next part – Arizona-Sonora Desert Museum

Random Quote #7

Posted by Tom on September 13, 2008

Posted in: Random Quotes.

“Pardon him, Theodotus; he is a barbarian, and thinks that the customs of his tribe and island are the laws of nature.”
— George Bernard Shaw; Caesar and Cleopatra

This should be taken to heart by everyone, no matter what they do or where they come from. –I know far too many people who simply can’t imagine anything but their way. –Sometimes, when I catch myself thinking this way, I have to step back and consider if I am acting like a barbarian.

Unboxing the EeePC 901

Posted by Tom on August 29, 2008

Posted in: Around the House, Technology.

I’ve been following the ASUS Eee PC, ultra portable laptop since it came out. but I felt the original 7″ screen was a little small and the storage capacity limited. That changed when they came out with the next model. I finally gave in and ordered a Eee PC 901 on August 20th. I got the 1.6GHz 20GB, Linux model and it arrived on Tuesday.

My first impressions are quite favorable. It’s fast and lightweight. The 9.8″ screen is bright and very readable. The Linux distro it uses is a version of Xandros and it is very complete. I have had no real problems with any of the numerous software packages that are pre-installed. It is easy to set up and use.

Best of all, it boots up like lightning – maybe 30 seconds total. Not quite instant on, but close. It is very practical to keep it handy and turn it on just to check the weather or news and then flip it off again. No agonizing wait for boot up or shut down.

Some of the features of this machine I really like are:

3 USB 2.0 ports, Ethernet port and an SDHC card slot that allows up to 16GB of additional, removable, storage.
Built-in Wi-Fi and Bluetooth
20 GB solid state HD (no shock and vibration worries) and 1GB RAM
Skype pre-installed with a built-in Web Cam for video calls
About the size of a hardbound book – 2.2 pounds with battery.

There were only a few problems:

I had trouble getting the Wi-Fi to work. Then I found out I had set up the wrong type of encryption for my network. Once that was fixed all was well.
I had a lot of trouble with the “tap” feature of the touch pad. I finally had to disable that since I was forever clicking when I didn’t want to. An external mouse is still a nice addition. The touch pad is okay for a quick check of email or a web site but I’m much slower using that compared to a mouse.
Using Thunderbird for email and USENET. It just does not have all the features I want. Maybe a later version will fix some of its problems but right now it is a bit of a struggle. On the other hand, it does work with no real bugs that I have found.
I haven’t found a version of TrueCrypt that can run in the GUI on this machine. The command line version is too cumbersome for me. This is minor but a nuisance as I worry about keeping unencrypted private info on a laptop.
the shutdown process hangs if you have Wi-Fi enabled. I think this is a known bug and there will probably be a fix one day. The work-around is to either be sure to turn off Wi-Fi before shutting down or to use the “emergency shutdown” (manual power switch).

Here are some pictures of the unboxing. Click on the thumbnails for a larger image.

When I opened the outer box I was dismayed that Amazon had not filled all the empty space with plastic air bags as is there usual procedure. Still, everything looked to be in good shape.

Here is how the inside of the box looked. Very well protected and everything intact. I guess the lack of padding in the outer box was not a problem.

Everything from the box spread out on the table. The battery is not installed in the PC so the back edge looks a little strange.

This is a shot of the screen and keyboard after I booted it up for the first time. Worked like a champ – looked cool.

In summary, I would recommend the Eee PC to anyone who wants a light, simple machine for email, web surfing and basic computing while traveling. You should not be afraid of Linux in this application. It works well and is easy to get used to. ASUS has put a lot of effort into making the interface as user friendly as possible while still retaining the parts that makes geeks love Linux.

I should caution that my personal biases should be considered before anyone takes my recommendation too seriously. As they say, “YMMV”.

I’m not a fast typist and don’t mind the small keyboard.
Low weight and small size are highly important to me when traveling.
I’m looking for ways to wean myself of Windows and Microsoft.
I am a nut when it comes to cool gadgets.

Rock Ends