Vintage Humor

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.

Updated PS/2 Adapter Firmware (version 3.0)

April 17th, 2014

I have enabled stretched as well as the possibility of an acked strobe output on my PS/2 adapter. I’m calling this version, 3.0. This should make it easier to use the adapter with some vintage gear, such as an OSI system, which doesn’t latch strobe, but only polls for it. Read the updated doc on my PS/2 adapter page.

skinned knuckles

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

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.

    SwyftCards Now Generally Available

    April 11th, 2014

    Swyftcard kits are now generally available for $55, which includes shipping.

    Check out my SwyftCard page for more information about the SwyftCard and Information Appliance, Inc.

    Or send email to:mike@willegal.net for ordering information.

    PS/2 keyboard adapter used with Ohio Scientific Computers at VCF

    April 10th, 2014

    It took a modification, but Bill Dromgoole was using my PS/2 to parallel keyboard adapter in his display of OSI computers at VCF east 9.1. (The link to the image of Bill’s setup from the Vintage Volts blog). The modification was to stretch the strobe output with a 74123 one shot IC.

    kb_adaptor
    PS/2 to parallel keyboard adapter

    I didn’t anticipate this when I made the design, but some vintage computers poll the strobe directly with software routines, while waiting for new input. My design assumed that strobe would be used to latch a flip flop (or equivalent), which would be reset by software when it actually read the character. I’m not sure how long Bill stretched the strobe, but with an 74123, it’s easy to adjust the pulse. Another person, told me at VCF that did the same thing to make the adapter to work with his vintage system. Unfortunately, I can’t remember who the second person was.

    At some point, I’ll probably look into stretching the pulse in firmware, or at least adding a configuration option to stretch the pulse.

    Problems with 8008 serial routines that posted

    March 22nd, 2014

    Just a heads up – the serial transmit routines that I have posted with the 8008 applications have serious issues. Though it was working for me, other were using serial ports that weren’t so forgiving and had problems with transmit. Finally Corey Cohen tracked down problems with start and stops bits used with the transmited data. As soon as I get a chance to check out the fixed routines, I’ll be updating all the applications on my 8008 application and BASIC pages. For those of you that can’t wait here is the code for a version that I think will probably work. This version is timed for 2400 baud.

    My OS/X emulator was also broken and needs an update, as well.

    OUTCHAR:

    NDI 177 ; mask MSbit
    CAL BITOUT ; STARTBIT
    CAL BITOUT ; LSB
    CAL BITOUT ; 1
    CAL BITOUT ; 2
    CAL BITOUT ; 3
    CAL BITOUT ; 4
    CAL BITOUT ; 5
    CAL BITOUT ; 6
    CAL BITOUT ; MSB
    LDA ; timing delay
    LAI 200
    OUT OUTPORT ; stop bit
    LDI 100 ; and extra for inter character spacing
    JMP MORE2

    BITOUT:
    OUT OUTPORT
    RRC ; shift to get next bit
    LDI 3
    MORE2:
    LAA ; nop to delay 5 states to make timing work
    DCD
    JFZ MORE2
    LDI 0 ; delay 8 states
    RET

    Reproduction SWYFT CARDs Arrived

    March 14th, 2014

    I just got my reproduction SWYFT CARDs in and they look and work great.

    Reproduction SWYFT CARD

    Reproduction SWYFT CARD

    I’ll be releasing them at VCF east in a few weeks. I’ll also be doing a soldering workshop in which you will be able to build one, even if you are a novice at soldering.

    Reproduction and Original SWYFT CARDs

    Reproduction and Original SWYFT CARDs

    The SWYFT CARD was used as a prototype/proof of principal implementation by Jeff Raskin’s company, after he left Apple after the falling out with Steve Jobs. Later they came out with the SWYFT Computer and the Canon Cat.

    Check out the VCF website for details on VCF east 9.1
    http://www.vintage.org

    regards,
    Mike W.

    Old Barndoor Telescope Sky Tracker

    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.

    Modelling a Time and Place: My Proposed Model Railroad

    February 25th, 2014

    Most model railroaders eventually work towards modelling a certain date and time. In some cases, the plan is to tell a bit of a story. I guess I’m moving towards the extreme end of things in my City Point model railroad planning.

    I was originaly thinking of modeling early December, 1864, when the Sixth Corp infantry returned from the Shennandoah Valley through City Point. This was to provide a viable reason to model a significant number of infantry using the port facilities.

    However, after some recent digging, I think I have come up with a much more interesting timeframe.

    In March there was heightened quartermaster activities related to preparations for a major campaign. On March 27th and March 28th, 1865, a lot was also going on at Army Headquarters.
    President Lincoln and family was in port aboard the River Queen, taking almost daily trips to see points of interest.
    Sherman arrived late in the afternoon of the 27th, leaving around noon on the 28th aboard the Bat, a captured blockade runner.
    Sheridan arrived late at night of the 27th.
    Admiral Porter was also present.
    There were several meetings among these men during the late afternoon and evening of the 27th and also the next morning.

    Up through the 28th, the 114th Pennsylvannia Zouves were on provost duty at City Point. The 114th Pennsylvannia had one of the best bands in the Army of the Potomac and it was known to serenade General Grant several times a week while on provost duty. They were still uniformed in Zouve attire, even at this late date in the war.

    Also…
    Several thousand prisoners were captured at Fort Stedman on the 25th – I don’t yet have information on transportation dates, but they were almost certainly shipped to prisoner of war camps through City Point, shortly after that battle.

    Newly recruited units were arriving in this general timeframe to reinforce the armies for the upcoming spring campaign. Because of the great need for troops during this period of the war, the Union armies didn’t wait for new regiments to completely get recruited, but would often send incomplete regiments to the front, following later on with remaining companies. An example of this is the 18th New Hampshire, which had 6 companies sent to City Point in September, followed later on by individual companies, as they were recruited. At first, the regiment was attached to the engineer brigade and helped build the City Point defenses. Later on, they did some service in the trenches. Company H arrived at City Point on March 30th. Company H was given weapons and rudimentary training on the 31st and joined the regiment in a firefight in the front lines the very next day. On April 3rd the 18th New Hampshire joined the army as they occupied the vacated Confederate trenches. They also participated in the pursuit of Lee’s army.

    Sounds like a fascinating time and place to model, what do you all think?

    regards,
    Mike W.