Archive for the ‘Misc Stuff’ Category

Keyboard Gizmos

Tuesday, July 15th, 2014
parallel keyboard gizmos

parallel keyboard gizmos

Here is a popouri of parallel keyboard projects that I have been involved with designing.

Not shown

  • A simple single chip AVR PS/2 to parallel keyboard adapter that I forgot about when I assembled the items for this picture.
  • At top is:

  • A reproduction Datanetics keyboard
  • At bottom, from left to right…

  • Home etched/prototype PS/2 to parallel keyboard adapter
  • Production PS/2 parallel keyboard adapter configured for Apple 1/Mimeo
  • Production PS/2 parallel keyboard adapter configured for Apple ][. The latest version firmware can also be used with other vintage computers
  • Home made Apple ][ keyboard to Apple 1/Mimeo motherboard dongle with clear switch - based on schematic at Wendel Sander's Apple 1 site
  • Production Vintage Micros Apple ][ keyboard to Apple 1/Mimeo motherboard dongle with clear switch. Similar to home made one
  • Corey Cohen’s parallel keyboard multiplexor. Automatically accepts and switches input from two different parallel keyboards to a single destination motherboard.
  • Not shown are a number of projects that I have started, but not completed (yet)

  • Datanetics replacement using modern components
  • MM5740 replacement using modern micro controller
  • And then there are the projects that never got past investigation stage.

  • ADB bus to parallel adapter
  • PS/2 Apple IIe keyboard adapter
  • It’s really hard to imagine that I have spent so much time mucking with simple parallel ASCII keyboard technology.

    Model Rocket Launch Circuit

    Saturday, July 5th, 2014

    A few years ago I built a launch controller for Estes type model rockets. This was designed to be powered by a 12 volt battery. I usually use a battery off a riding lawn mower or motorcycle. When I was a kid I used to use a motorcycle battery that had a bad cell to launch model rockets and it worked great.

    complete launch control

    complete launch control

    This controller has two cables that are used to carry power from the battery to the ignitor.

  • A pair of clamps at the end of 10 feet of cable are used to connect to positive and negative terminals of a 12 volt battery.
  • A pair of small alligator clips at the end of 20 feet of cable are used to connect to the rocket engine ignitor
  • launch controller

    launch controller

    This controller has the following features.

  • A 1/4 inch phone jack used as a safety key. With the plug removed from the jack, the power is disconnected from the ignitor circuit.
  • A two color green/red LED – The LED’s red light is lit when power is available from the battery. The LED’s green light is lit when the safety plug is installed and power is available. Since both LEDs are lit when power and safety plug is installed, the resultant light looks yellow.
  • A green LED that lights up when power is available, the safety plug is installed and the ignitor is connected.
  • A red button that will launch the rocket if all LEDs are lit.
  • Now the reason for this post. The last time I used this controller, I did have a rocket launch imediately when I inserted the safety key. The LED that indicates that the ignitor is connected was designed to draw 10 milliamps through the ignitor and that current is flowing when the safety key is inserted. Though I tested that current through a number of ignitors, it must have been enough current to fire the one that went off prematurely. What I have decided to do was to substantially reduce the test current through the ignitor. The easiest way to do this was to use a smaller test current through the ignitor and use a transistor to amplify the current to a level high enough to light the indicator LED.

    Here is modified schematic. By the way, don’t bug me about the LEDs which are shown connected backwards in this drawing.

    launch controller schematics

    launch controller schematics

    With this design the test current through the ignitor can be roughly calculated as:

    12 volts/100000 ohms = 120 micro amps

    I think that this tiny current would be extremely unlikely to launch a rocket inadvertently. I measured the current through the LED as about 30 milliamps. This means the transistor is multipling the current by about 250 times.

    So Who Wrote that Anti-Bellum (Pre Civil War) Love Letter?

    Tuesday, June 3rd, 2014

    It was U. S. Grant, future leader of the Union Armies during the Civil War and President.

    So what kind of man was Grant.

    As you might guess, all accounts indicate his family life had an almost storybook quality about it, always being faithful to his wife, Julia, and being a loving father.

    Grant was a no-nonsense type man. As a general during the war, he formed strong opinions of the people around him and whenever possible, acted upon these opinions, putting those he trusted in positions of authority, and casting aside those he didn’t trust. He was extremely demanding, and had high expectations of those under him. I believe his success as overall leader of the Union armies was largely due to his ability to find and promote people of great ability to execute his plans.

    Though known as a poor president, his politics were those of a radical republican, and his administration was challenged by the extreme difficulty of reconstructing a shattered nation. Though the Confederate soldiers put down their weapons, most of them never changed their political views. His liberal views toward the freedman, and strong will, rubbed many people the wrong way. Though he was extremely popular in his time, once the “lost cause” movement gained a toehold, his generalship and politics were roundly criticized. Recent scholars have been more kind to him.

    Remembering Original D&D, TSR and FITS

    Friday, May 30th, 2014
    D&D Reprint

    D&D Reprint

    I recently picked a reprint of the original version of TSR’s Dungeon’s and Dragon’s. It’s a reprint of what many people call the white box version of D&D. Actually the first few printings of D&D came in wood grain cardboard boxes. After a few printings they changed to a white box.

    D&D 3rd printing

    D&D 3rd printing


    This image is a third printing that I sold for $1600 a few years ago. My first copy was a first printing that I bought from Brian Blume. This was right after spending a Sunday afternoon in Gary Gygax’s basement exploring Greyhawk, his fantasy land. At that time, they sold the game by inviting people to play it. I believe that Brian told us at the time that they spent several thousand dollars printing that first 1000 copies. I think I learned later that Brian’s father financed the early TSR projects. I don’t know what happened to that 1st printing copy of D&D. I’m sure it was pretty well worn out, as we played the game quite a bit, back in the day. The 3rd printing copy I sold for so much, was a replacement for a worn out first printing that I picked up directly from Gary Gygax who often manned the TSR booth at GENCON.

    Batwing - D&D circa 1975 & 2014

    Batwing – D&D circa 1975 & 2014


    My kids and their friends have recently enjoyed a few trips down into my old dungeon, which is called “Batwing”. Amazing that this old game still can capture the imagination of young people. Maybe more amazing that I held onto that binder for all these years.

    FITS Box Cover

    FITS Box Cover


    Now if I could only convince them to give “Fight in the Skies” a try. “Fight in the Skies” is a World War 1 air combat game that has an element of role playing. FITS is said to be the one game has been played every single year at GENCON. Back in the day, I know I played FITS more than once at GENCON with Mike Carr, the author of the game.

    Speaking of FITS, GENCON, Brian Blume and Mike Carr, I’ll never forget the first GENCON South in Jacksonville, Florida in 1978. At this time I was friends with a number of the TSR staff, but living far away in South Florida. Mike Carr and Brian Blume made the trip to Jacksonville to represent TSR. Some friends and I drove up to Jacksonville from South Florida. We ended up going out to diner with Mike and Brian. At one point, I told them that computer gaming wasn’t likely to take off, as the interactive social element wasn’t as strong in computer games as other forms of gaming. Most computer games in 1978 pitted you against the computer, or required multiple players to take turns at the controls. Boy, was my vision wrong. I hope I didn’t affect their business plans too much with my bad advice.

    FITS Rules Book and Pilot Cards

    FITS Rules Book and Pilot Cards


    Speaking of FITS. I still have my pilot cards. My two best pilots are a German Albatros DIII pilot with 21 missions/1 kill and a Brittish Sopwith Camel pilot with 14 missions and 3 kills. By the way, during one of the reprints TSR or Wizard’s of the Coast renamed the game, “Dawn Patrol”. There appears to be an active group of people still playing it.

    Which Civil War General Wrote this Letter to his Sweetheart.

    Friday, May 23rd, 2014

    I had to share this – I have changed some of the names to make it harder to figure out the answer..

    Corpus Christi Texas
    Jan. 12th 1846

    My Dear Nancy,

    I have just been delighted by the receiving a long and interesting letter from the one I love so much and from the tone of her letter I am left with the hope that for the remainder of the time that we two are not one, she will be punctual in answering my letters. You do not know the pleasure it gives me to receive letters from you my Dear Nancy or you would write oftener. I write to you very often besides answering all your letters. You beg of me not to resign: it shall be as you say Nancy for to confess the truth it was on your account that I thought of doing so, although all the letters I get from my father are filled with persuasion for me to resign. For my own part I am contented with an army life, all that I now want, to be happy is for Nancy to become mine, and how much I would sacrifice if her parents would give now their willing consent. By Spring at farthest I hope to see the 4th Infy (You know that I have transferred from the 7th to the 4th) settled and that too on the Mississippi river, unless something should take place to give us active employment. Has Mr. Reeves ever delivered you the letters sent by him. It is astonishing Nancy what a place Corpus Christi has become. Already there are two Theaters and a printing office every night there is a performance play at one or the other. It seems strange to hear you talking of sleigh riding, for here we have although it is January weather warm enough for light clothing. Such a thing as a sprinkle of snow is rarely seen at Corpus Christi.

    From my last letter you will see that I have been on a long trip through Texas and that I think the country beautiful and promising. If it should turn out after all that my Regiment should be retained here (it is not the opinion of any one that it will be kept) I could have but little to complain of. Your letter. and indeed all your letters, show your willingness to accompany me to any permanent Military post. It is very pleasant to hear such confessions from the one we love and in return I have to say that I would make any sacrifice for my Nancy’s happiness. But what an uninteresting letter I am writing you it seems to me that the more I write the worse I get.—I have not heard from Fred, since I have been in Texas. I have written to him once and I think twice since he wrote to me last. Tell him he must write soon. Fred is now about 3d for promotion. There has been two resignations at Corpus Christi that he has not heard of.—Mr. Ridgely and Mr. Sykes have gone to St. Louis on a sick leave; if I had known sooner that they were going I would have sent a letter by them.

    I have written you several letters that remain unanswered so I shall look for another letter in every Mail. Give my love to all at White Haven. Soon I hope to see you again my dear dear Nancy and let us hope that it will be to never separate again for so long a time or by so great a distance.

    Your Devoted
    Ronald

    A Clue…
    Mary Lincoln supposedly once said of this man
    “He is a butcher and is not fit to be at the head of an army. Yes, he generally manages to claim a victory, but such a victory! He loses two men to the enemy’s one. He has no management, no regard for life.”

    In case you can’t figure out who the author of the letter was, I’ll add another post in a day or two with the answer.

    Vintage Humor

    Friday, April 18th, 2014

    I found this in Volume 1 – Issue IV of the SCELBI Computer Digest, which can be found online at scelbi.com.

    THE NAVAL ADMIRAL HAD JUST PURCHASED A MINICOMPUTER TO HELP HIM RUN HIS MIGHTY FLEET. HE QUICKLY UNPACKED HIS UNIT, SET IT UP IN HIS STATE ROOM, PLUGGED IT IN, AND WITHOUT WASTING ANY TIME.. PROCEEDED TO ASK HIS NEW COUPUTER AN INPORTANT QUESTION.

    “WILL THE WEATHER BE SUITABLE FOR LAUNCHING PLANES FROM MY AIRCRAFT CARRIER TOMORROW – OR WILL IT RAIN?”
    “YES.” ANSWERED HIS NEW LITTLE BRAIN.
    “YES WHAT?” SHOUTED THE EXASPERATED ADMIRAL.
    “YES SIR!!” PIPED UP HIS LITTLE MINI.

    skinned knuckles

    Sunday, April 13th, 2014

    Last night, a little after midnight, I finished replacing a power window regulator in my wive’s mini-van. I’ve done motors before, but not the regulator. I expected the job to come with a few obstacles to overcome and I wasn’t disappointed. I’d like to know how they connect the lock rods and lock actuator in manufacturing – what a pain. It also took some time and effort to get the window properly seated in the regulator guides, but I think that might have been an issue with the aftermarket regulator that I bought.

    The reason why I do this is cost – my cost was $70. The last time I had one repaired by a shop, it was over $400.

    Proposed PS/2 Keyboard Adapter Stretched Strobe Change

    Friday, April 11th, 2014

    As I mentioned in a previous post, my PS/2 keyboard adapter requires some strobe stretching in order to work with some kinds of early microcomputers, such as some OSI models.

    I think I have come up with a convent way to accomplish this, with only a small firmware change.

    Here is what I have in mind.

    As before, when the CR jumper is inserted, it disables recognition of the CNTRL-RST and CNTRL-CLR keyboard/RS232 sequences, which assert the reset or clear screen outputs, as appropriate. With my new design, in addition to disabling the aformentioned reset and clear sequences, inserting the jumper will change the clear screen output to an input. Now here is the key part of the change; whenever a character is typed and strobe is asserted (high true), if the CR jumper is inserted, strobe will remain asserted until:

  • minimum of 125 useconds have elapsed AND
  • the input to the clear I/O port is asserted (also high true)
  • To maintain current behavior (a 125uSec long pulse), you just need to tie the strobe output directly to the clear input.

    In order to stretch strobe out a bit, you have a few options:

  • Tie strobe output to clear input through an RC timing network in order to slow down the response to the clear input. For example – connect strobe and clear together with a 10K resistor. Then connect the clear input side of the resistor to a 1 uF capacitor and connect ground to the other side of the capacitor. Doing a basic RC timing equation shows that this should yield a delay of approximately 10 milliseconds. Change the values to attain a strobe length that meets your requirements. You do have to be careful to limit current through the resistor, so you don’t blow the strobe transmitter, though.
  • Use external logic of your choice to assert the clear signal to the PS/2 adapter
  • Behavior with the CR jumper disconnected is exactly the same as with the previous version of firmware.

    The main assumption behind this change is that the clear output, is only required for the Apple 1. I have found little to no need to disable CNTRL-RST and CNTRL-CLR on the Apple 1 (or Apple II) and those features are probably of little value to other platforms. In any case, the PS/2 keyboard sequence of CNTRL-ALT-DEL will still assert reset no matter whether the CR jumper is in place or not. In fact, using the CNTRL-ALT-DEL combination from a PS/2 keyboard will be the only way to assert reset if a system needs both reset AND a stretched strobe output. Said another way, you will not be able to assert reset from a device connected with the RS232 port, if your system also needs a stretched strobe.

    I’ll do some trials over the weekend and assuming that it works ok and I get no better input or ideas, I’ll have a new version of the firmware available very soon, possibly as soon as next week.

    Old Barndoor Telescope Sky Tracker

    Wednesday, March 5th, 2014

    Barndoor Tracker Movie (click on this link to see movie)

    I recently pulled this old 2006 project out of mothballs and it still works. You mount a small camera or telescope on it. You point the axis at the celestial north. Turn it on and it follows the rotation of the earth, so you can take long exposure pictures of the night sky. I only took one roll of film using it and before I was able to take a good look at the results, the negatives disappeared, so I don’t really know how good it worked.

    It features speed, direction controls and a clock for timing the exposure.

    Visiting Arlington National Cemetery, August, 1964

    Friday, November 22nd, 2013
    Arlington National Cemetery Aug, 1964

    Arlington National Cemetery Aug, 1964

    Arlington Nation Cemetery, second picture

    Arlington Nation Cemetery, second picture