Aucbvax.1370 fa.info-micro utzoo!duke!mhtsa!ucbvax!CSTACY@MIT-AI Tue May 19 19:17:32 1981 INFO-MICRO Digest V3 #43 INFO-MICRO AM Digest Monday, 18 May 1981 Volume 3 : Issue 43 Today's Topics: Floppy Disks - Shipping Protection, Rossetta Smalltalk, Data Compression - Huffman Techniqueues RS232 Touchtones, Video Monitors ---------------------------------------------------------------------- Date 22 April 1981 01:25-EDT From: DWS at LLL-MFE Subject: Shipping disks through the mail The other day I had the dubious joy of finding a large manilla folder folded over double and stuffed into my apartment mailbox. The folder was marked on both sides with "Do Not Bend" and "PLEASE Do Not Bend" in big letters, and contained a manual for some soft- ware I had recently purchased and a floppy, both neatly creased. The manual was still readable, the floppy was not. A friend tells me that he has had the same problem several times, and that complaining to the Post Office doesn't seem to help. I doubt that marking a package "Contains Contact Explosives -- Please Do Not Bend" would make matters any better, and shipping floppies in big metal boxes would seem to be overkill. The fault is not completely the Post Office's, however. Software dealers should take some care in shipping their products, and not assume that anything going into the mailbox will come out intact at the other end. The only reinforcement in the package I received was a piece of cardboard. I would be very interested to hear how others have dealt with this problem, and what kind of precautions you software dealers or other disk shippers out in Info-Micro land take when shipping disks. -- Dave Smith ------------------------------ Date: 25 April 1981 23:27-EST From: Brian P. Lloyd Subject: Mailing Media Floppies get mailed via Federal Express (never US Mail!). The disks are protected by two pieces of three-layer corrugated cardboard. So far, all disks mailed this way have arrived alive. Brian Lloyd ------------------------------ Date: 28 Apr 1981 1458-PDT From: WRS at OFFICE-2 (William R. Soley) Subject: Shipping disks through the mail On the subject of mangled floppies, Gorden French owns a company called Square One who manufactures a floppy mailer which is supposed to be pretty good and pretty inexpensive (although I've never had occasion to use one). At one point he was giving out samples (1 each) if you mail him a request on letterhead or include a business card. Even if he's not giving away samples anymore, I'm sure he'll be glad to tell you all about them if you write to Square One 1134 Crane Menlo Park, CA 94025 (415)325-4209 You might mention that you heard about him from a member of the Homebrew Computer Club. -Bill ------------------------------ Date: 24 April 1981 12:24-EST From: John Howard Palevich I've looked at & played around with Rosetta Smalltalk. The version we had was custom assembled for a 56K CP/M and an ADM3-A @ 19.2Kbaud. It's basicly a toy. With the interpreter & the editor (which IS written in small-talk) in, you get about 10K. It takes about 10 minutes to load in short program files. Oh well. Many errors will cause smalltalk to stop working. I have read (in CC and Byte) that Xerox was very angry at Rosetta for using the name smalltalk. Looks like another Unix(tm) deal. ------------------------------ Date: 29 April 1981 19:00 edt From: Schauble.Multics at MIT-Multics Subject: Data compression I have a design (not yet ever implemented) that did compression for data transmission by assigning two byte codes to the 1000 most common English words, and expanding these on the far end. If what you are transmitting is text, you should definately add this to the protocol. I discovered that 1000 words is overkill. Half of the characters are in about 100 words. So, I think a personalized or adaptable word list of 200 or so words would be plenty. This can be combined with the Huffman code by considering both words and single characters as code elements, and constructing Huffman codes until you have accounted for all single letters. It is not necessary or desirable to code words that are less common that the least common letter. In fact, optimum transmission has you cutting out some words that are less common than the least common letter. I never figured out a rigorous way to do this. If anyone has one, I would like to know about it. ------------------------------ Date: 29 Apr 1981 at 1643-PDT From: knutsen at Sri-Unix Subject: Re: Data compression Seems to me (tho I havent studied this stuff much) that the optimal coding would use variable length keys, ie tokens of 1 letter, 5, or even 3 4/7 perhaps, to build the Huffman tree. However when you do this kind of thing, you run into two tradeoffs: how much info on the coding tokens used you have to put into the output, and how long it takes to de/code. ------------------------------ DEVON@MIT-MC 04/27/81 22:35:09 Re: Touch Tone => RS-232 I worked on something called "Samantha" for Telecheck, which uses Ma Bell 407 modems and a Votrax LVM-70 (expensive stuff!) and it can answer the phone, say canned words & phrases, and wait for Touch Tone Response, which comes out in ASCII. You type ## for and you can get into and out of "aplhanumeric mode" with #0 and #9. In this mode you hit two-digit pairs for some (not all) ASCII codes. I think that "$" is "35" which is based on the memnonic "DL". Homebrewing a T-T => EIA circuit is something I never thought of until now, but with a $150 talk-box (rumor?) it would make an interesting CBBS variation. ------------------------------ Date: 28 Apr 1981 1457-PDT (Tuesday) From: Lauren at UCLA-SECURITY (Lauren Weinstein) Subject: Touch Tone => RS-232 My old Touch-Tone Unix system was like that -- full touch-tone to ASCII translations via a very intutitive easy-to-learn mapping. My strange home computer here (Z80 based), currently has 103, Vadic 3405, and 212 dialin/out capability. I am currently making the final arrangements for voice out/touch-tone in and voice out/voice in. Should be amusing. --Lauren-- ------------------------------ Date: 24 April 1981 10:38-EST (Friday) From: Andrew G. Malis Subject: Direct input TV Two suggestions: 1. In the January 1981 Consumer Reports, they had a report on 19-inch color TVs. They singled out the RCA VEM575W (list price $680) as being able to accept two video inputs as well as off-the-air reception. They say the inputs were meant for direct hook-up to video cameras without the use of an RF modulator, so this is probably just what you want. By the way, the RF tuner is the quartz-type with a calculator-like keyboard for choosing the channel with two keypresses. The set can also receive cable TV channels A-I without an external converter box. As a companion to their new color computer, Radio Shack now sells a color TV with a tuner (also calculator-type for 2-button direct channel choice, all 83 broadcast channels) that also can be switched over to take its input from the color computer. However, I don't know whether the input is direct NTSC or RF-modulated. Andy ------------------------------ From: chesley at Sri-Unix Subject: Composite video to RF conversion Since someone brought up a related question, I've been wondering for awhile if I could use my video tape recorder to convert from composite color to RF. It's a standard RCA VHS recorder, with video in/out as well as RF in/out. I used the output once to check my monitor, but I've never tried it the other way, nor with color. It could be quite convenient to have everything switched thru the recorder. --Harry... ------------------------------ Date: 24 Apr 1981 1247-PST (Friday) From: Lauren at UCLA-SECURITY (Lauren Weinstein) Subject: Composite video to RF conversion If I understand your question right, there is nothing stopping you from running whatever you want through your VTR. I have frequently run computer generated composite video through my machines for quick checkout purposes. The RF modulators in most current VTR's are pretty decent. However, I have never wanted to tie up the inputs on my machines that way, so after testing I'd always install a dedicated modulator on an unused channel for permanent use. --Lauren-- ------------------------------ Date: 24 Apr 1981 1238-PST (Friday) From: Lauren at UCLA-SECURITY (Lauren Weinstein) Subject: monitors I have trouble understanding what good it is to receive cable midband channels A-I when you can't get all the rest directly -- you'll still have to use a converter box to get the missing ones. Frankly, : I think that anyone who is serious about video displays (for TV watching, computers, or whatever) who doesn't buy SONY is misguided. Whenever you see a monitor on television in the backround, look at the bottom of the screen for the SONY logo, (or a piece of tape covering the logo!) SONY is extensively used in broadcast, and manufactures the finest general purpose monitors I know about. I would never buy anything else. --Lauren-- ------------------------------ Date: 24 April 1981 21:56-EST From: Brian P. Lloyd Subject: monitors I agree with Lauren re. video monitors. While I was employed by PBS I discovered that they had monitors using the Sony Trinitron(tm) color tube (the monitor was actually by Tektronix). There was a problem however: the system was so good that it tended to produce good display even though the quality had dropped. A junky old monitor was kept handy as its picture degraded badly if the quality of the video dropped even a little. Brian Lloyd ------------------------------ End of INFO-MICRO Digest ************************ ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.