zaitcev.mee.nu

While a university student, I held a side job at a small company "Micros" that developed a COM-port network. It was a somewhat common thing to do, not much different from the original AppleTalk in cocept.

Although AppleTalk was a bus with a CSMA/CA protocol, Micros was a token ring. A station plugged into a ring through a tap with relay driven by the DTR signal. Thus, if the COM port was not open or the PC was turned off, the station was electrically disconnected from the network. Not a surprising design for the years when people thought FDDI was a good idea.

Most of the software for the network was written in Modula-2 and stayed resident in MS-DOS, providing remote access to files. It was in the days when a PC AT with a 12 MHz CPU and 1 MB or RAM was the gold standard.

Come to think of it, I cannot remember what I ever accomplished at that place. I worked hard and was paid relatively well, but I just didn't do anything noteworthy. However, I met some interesting personalities.

Owner of the company, Mr. Andrey (?) Kinash, graduated from LesTech, or the Forest Technology Institute, a narrowly famous univirsity that was divided in half between the forest stuffs and the space and rocket science. Running a company during the final days of USSR wasn't a trivial undertaking.

Our team lead was my friend Anatoly Voronkov, who wrote most of the software. Other members were myself, Marat Shafigulin, and Vladimir Roganov. Vladimir wrote a rather interesting error correction code for us. At the speed of 115,200 baud, bytes arrive quickly enough that the unbuffered UART in PC dropped them when MS-DOS disabled CPU interrupts. Every time the 55ms timer hit, we lost something like 3 bytes. The challenge, thus, was to develop an erasure code that could recover not from corrupted bytes, but from lost ones. Althuogh, I think, our low-level framing provided some idea of how long the packet should be, the code could not know the position of the lost bytes. IIRC, Vladimir's code expanded the data stream by less than 10%.

All of that was rather nifty, but of course the arrival of cheap Ethernet made such networks obsolete.

One of the firm's locations was a basement that we called "Kinashevnik", for obvious reasons. It had rats and we generally got to know them, because everyone loved to work overnight. That was when I learned that a rat can gnaw through almost anything, including concrete. The only thing that could stop it was a metal plate. Anatoly then had a brilliant insight that we ought to plug rat holes not with something sturdy, but with something that was not in rats' taste. We found a type of packaging foam that apparently tasted disgusting enough to rats that they would not gnaw through it, and used it to plug rat tunnels.

Next: Memoir 7.

Posted by: Pete Zaitcev at 09:34 PM | Comments (1) | Add Comment
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