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 <LLOYD AT MIT-AI>
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 <TANG AT MIT-AI>
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 <RETURN> 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 <MALIS BBNE AT>
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, <BIAS MODE ON>: 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. <BIAS MODE OFF>
--Lauren--
------------------------------
Date: 24 April 1981 21:56-EST
From: Brian P. Lloyd <LLOYD AT MIT-AI>
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
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