The Microship Status Reports

Microship Status 1/19/94 by Steven K. Roberts

In This Issue:

Quick Updates On:
Digital Ocean Wireless Appletalk
Mcs Network Hardware Status
Gps Interface
A Forth Real-time Clock Program

No major articles today, just more quick status updates. I realized I was getting into a feature-writing mode, treating this as a forum for relatively long and coherent pieces which are hard to get around to doing. That's what the Nomadness Notes and the corresponding hardcopy newsletter are for. This series of project status reports, on the other hand, should take the form of timely and relevant news of interest to anyone close to the project, with only occasional tutorials and full-scale articles.
Today's news....

A discussion with Digital Ocean (Overland Park, KS) revealed the happy news that they are close to shipping their Grouper product, a very cool wireless AppleTalk link. We'll have a pair of these on the ship to allow the PowerBook to be present on the ShipNet while off-boat. Initial experimentation (around April) will use their current product, which assumes LocalTalk connection to the Mac host; later we'll replace that with a new unit that will live on the Ethernet (the ship's networking backbone).
IEE (waterproof keyboards) is down due to the quake, and I left a message for Sharp (color LCD for the Ampro system). Frank Araullo is planning to bring up the Ampro, and we need to borrow a video monitor from someone until the LCD arrives.

Dan Yang ventured into the world today, picking up 100' of RG-8X coaxial cable from Ham Radio Outlet and the SIP connectors for the FORTH boards from Gateway. Agnes ordered the power connectors from Mouser, and I'm spending time this evening hardware-configuring the NMIS-5000 serial board that will let the Hub processor talk to the multidrop network via modified RS-422.

Henry Xia and Dan worked with the Motorola Traxar GPS for quite a while today, eventually getting it interfaced (4800 baud) with the Zenith laptop and quite happily displaying navigation sentences at a 1-second rate. Of course, the data in the lab gets a bit boring after a while, but at least Henry can now start working on sentence parsing and so on. We'll need to interface a serial board to his FORTH node.

Delon Levi and Luke Abbott met here tonight to discuss the video crossbar requirements, and are now trying to figure out what the standard video signal level/format through the net should be (video only, NTSC, or whatever). I welcome suggestions from anyone who has dealt with video at this level. Delon contacted Mitel today (makers of 8816s and other crosspoint chips) and discovered that they have a new model (88V32) that has internal ground paths and other crosstalk-minimizing features that enable it to work well with video. Samples are enroute.

A Forth Real-time Clock Program

I spent a few more minutes playing with the real-time clock on the Hub, and wrote a simple program that displays the time on the 2-line LCD:
: DIGIT C@ 30 + DSP-EMIT ;
: SECS C001 DIGIT C000 DIGIT ; : MINS C003 DIGIT C002 DIGIT ; : HOURS C005 DIGIT C004 DIGIT ;

: Colon 4a Dsp-emit ;

: Time Hours Colon Mins Colon Secs ;
: DELAY 1000 0 DO LOOP ;
: CLOCK BEGIN CLEAR TIME DELAY 0 UNTIL ;

DIGIT simply fetches the BCD values from the memory-mapped time buffers (starting at C000) and adds them to the base value for ASCII numeric digits.

Note that the "BEGIN xxxxx 0 UNTIL" is an easy way to create an endless loop, since the 0 on the stack always ensures that UNTIL will never be true. Hitting the processor's RESET button is the only way to end the program short of the power switch, a hammer, large-scale static discharge, or physical chip removal.
What's wrong with this as a programming example is that the memory addresses for the time values are embedded in inline code. It was just a quick interactive keyboard hack -- a more elegant solution would be to define a base address with offsets, read the values with a loop, integrate the date, add setting and alarm features, etc. I leave these and other refinements (such as display in Katakana text strings) as exercises for the reader...

Ain't technology wonderful?

Cheers, Steve