Tuesday, May 27, 2014

Save the antelope!

Save the antelope!  Via reader Simi L...

Painters have arrived...

Painters have arrived ... and they went right to work.  I'm still surprised every time a workman shows up on the day and time they say they will. They're working to some songs I haven't heard for many years: Hank Williams, Patsy Cline, Kitty Wells, etc. My mom would feel right at home...


“Cosmic copyright law”...

“Cosmic copyright law” ... underlies a new “theory of everything”...

When I read the headline, my first thought was: “Oh, no!  The lawyers are extending IP to the entire cosmos?!?!?!” 

Odd rock on Mars...

Odd rock on Mars ... and Curiosity is checking it out!

Aleck, this is a teletype...

Aleck, this is a teletype...  My young friend and former colleague Aleck L. once found it hard to believe something I told him: that in the early days of microcomputing, we used mechanical teletypes to interact with the computer – and even to load software.  Well, here's a video of exactly such a setup, in action!

The teletype that I owned (affectionately nicknamed “Ralph”) was a different model than this one: it was a Model 28 Baudot code (five bit code) machine, and not the eight bit Model 33 shown here.  Consequently it couldn't read the 8 bit tapes that Microsoft sold their Basic on – so I built a 8 bit tape reader based on photo diodes (instead of the mechanical pins used to sense the tape holes on the teletypes).  When I received my paper tape of Microsoft Basic, my first attempt to read it was a complete failure – the tape was semi-transparent, and my tape reader couldn't distinguish between the holes and not-holes!

In sheer frustrated desperation, I unrolled that entire paper tape into a large bucket, and dyed it with black fabric dye.  The next day I pulled out the tape (now nicely blackened) and let it dry for a couple of days.  The next attempt to read it worked flawlessly :)

There was another, more technical issue as well: the checksum loader (referred to on the video) was designed to work with hardware I didn't have: an Altair or an IMSAI computer.  My computer was a home-built Z80 based computer with completely different serial IO.  So I had to reverse-engineer the checksum loader, and write the equivalent to work on my own computer.  The first step to reverse-engineer it was to read it (by Mark IV eyeball) from the paper tape, generating a hex machine code listing.  Then I manually reverse-assembled it, then actually figured out how it worked.  Ah, those were the days!  The equivalent would be a lot more difficult today...