Archive for January, 2011

A Version of Bill Gates’ (Microsoft’s) First Product – Altair 4K BASIC

Saturday, January 22nd, 2011

I found this today cleaning up the basement. This is an audio cassette shipped by MITS in 1977 containing an FSK version of Altair (Microsoft) 4K BASIC for the Altair 8800 computer. My Dad and I built our Altair in 1975 and finally got enough memory (5K) to run BASIC.  We used the Altair ACR board hooked up to a cassette tape recorder to load the software. The cassette was also shipped with a snippet of ASR-33 paper proving that this cassette loaded on an ALTAIR- along with a statement of free memory.  I wish I still had the snippet – but it most likely has been lost to the ages. The back side of the cassette has hand written 125/256 so I suspect this was a batch of 256 cassettes. There were apparently earlier versions since this is listed as version 4.0.

An audio cassette containing MITS 4K BASIC

Handwritten back side

My MTK 3329 GPS Reset Solution – Arducopter

Friday, January 21st, 2011

I ordered a new MTK 3329 GPS module and tested last weekend on my Arducopter.  The new one works fine in the cold – no more resets back to NMEA.  Very strange issue on my original MTK.

My Arducopter GPS Hold Issue – MediaTek MT3329 GPS resetting in cold weather

Tuesday, January 11th, 2011

I’ve been flight testing my Arducopter since Christmas with excellent flight performance (RC2 firmware) but mixed results for the Gps hold function.  I finally tracked the issue down to my MTK GPS resetting itself while running the September firmware when it is cold. The GPS runs great indoors as verified in my XBEE serial monitor using the “4” selection, but would stop reporting a position (TOD stops updating) a few minutes after I was flying in cold weather (20 degree F). I used my USBEE logic analyzer to figure out what was going on and I see the proprietary binary protocol change to the default NMEA protocol when I place the Arducopter outdoors.

The LA showed the output in proprietary format at a 5 Hz rate stopping for 2 seconds and then a $PGMOD message with the default NMEA output resuming just after. The blue light on the MTK carrier board maintains a solid blue light through the reset which was fooling me when trying to test the GPS hold in flight. I checked the 5 volt power going to the GPS when the event happens and everything is fine so it seems my MTK is temperature sensitive.

My MediaTek is an older one (purchased in late Summer 2010) with a coin battery on the back and I’ve ordered a new one. I just wanted to give a heads up to others since the the switch back to NMEA was so weird when trying to get the GPS hold to work.

Here is the USBEE screeen capture showing the serial port messages changing to the default message format during the MTK reset, the left packets are the proprietary messages at 200 msecs, then a pause, a reset message, and then NMEA packets. (Love the USBEE by the way):

GPS Reset Event

My New Arducopter

Monday, January 10th, 2011

A great flying quad-copter:

My New Arducopter

I’m having some trouble with the MTK GPS and the winter weather in St. Louis, but otherwise, this is the best flying copter I’ve ever had. It has a GPS/barometric pressure/sonar rangefinder  driven autopilot that will be able to fly waypoints and come home on command. I’m working now on a tilt/pan video camera transmitted to the ground and commands on a bidirectional data link (XBEE). Highly recommended and available at: DIY Drones.