Integers vs. Long Integers Was: RE: [AccessD] Global Variable

>You are calling your 3 bit group  a Byte 

I never called "my" 3 bit group a byte.  Where did I say that?  In fact it
most assuredly isn't "my" three bit group.

I have no idea what a three bit group is called in fact.  I know that a 4
bit group is commonly called a nibble, an 8 bit group is commonly called a
byte and from there it gets rather confusing.  16 bits used to be called a
word, 32 bits a long word or a double word, and now we have 64 bits.

What I said was that the 9 bit group that you were talking about was
probably made up of multiples of 3 bit groupings since octal (the name for
the math system based around 3 bit groups) was so common back at the time
that the computer you referenced was designed.

I was under the impression that YOU were calling your 9 bit group a byte.

>Did you ever set a single group of 3 bits  by itself or was it always
something like "777" to enter a character/opcode etc?

http://ed-thelen.org/comp-hist/univac-ntds.html will show information about
the Univac 642 processor which, on about the 2nd page down, shows pictures
of pages from a manual with instruction set material.  You can see pictures
of the front panel with groups of 3 bits clearly defined but no groups of
nine bits.  I never worked with 9 bit groupings per se.

This machine BTW was the second machine I learned to fix, in 1972-73 in
Vallejo (Mare Island), California.  It was designed in 1958 and when I left
the navy in 1978 it was STILL the "mainframe" that processed all the data
for the intelligence centers of the aircraft carriers (where I worked)
although it was being phased out.  Kinda scary eh?  An instruction cycle of
either 8 MICRO SECONDS (eight clocks) or 4 micro seconds (4 clocks).  32
Kwords of core memory.  The size of a refrigerator, consumed 4 Kwatts.
Little PC cards with individual resister/capacitor/transistor/diode based
logic circuits.  Each card would have a flip/flop, a pair of AND or OR gates
etc.  The cards built up registers and stuff.  The machine had 13 trays of
these cards.  We were taught to troubleshoot these machines to the card
level, using schematics, oscilloscopes, and an intimate knowledge of the
machine architecture.  You entered instructions on the front panel by
pushing switches (the octal groups) and executed them, then observed the
results on the front panel and on the O'Scope.  

Believe it or not, when I went to school on them, we would enter out
programs on the front panel and dump them to paper tape which we would carry
around with us as we developed out programs.  I remember going down to San
Francisco to a surplus store to buy 1/2" mag tape for my personal use so I
could get copies of the games that someone wrote for the machines.

The "good old days".

John W. Colby
www.ColbyConsulting.com 

Contribute your unused CPU cycles to a good cause:
http://folding.stanford.edu/

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Stuart McLachlan
Sent: Thursday, May 19, 2005 6:27 PM
To: Access Developers discussion and problem solving
Subject: RE: Integers vs. Long Integers Was: RE: [AccessD] Global Variable


On 19 May 2005 at 12:33, John W. Colby wrote:

> 
> >Look up Byte :-)
> 
> Yep, I know about byte.
> 

Clearly you don't. 

You are calling your 3 bit group  a Byte because you were using octal 
notation and a 3 bit group is represented by a single octal character.   By 
the same reasoning a Byte on your current PC is 4 bits  because we commonly 
use hexadecimal notation which allows a 4 bit group to be represented by 
one character.  

External representation of the bit pattern has nothing to do with the 
meaning of a Byte.  

Did you ever set a single group of 3 bits  by itself or was it always 
something like "777" to enter a character/opcode etc?

Since 36 bit word systems generally used  *multiples* of 3 bits for a byte 
(commonly 9 but sonetime 6 or even 15),  using Octal notation to represent 
bit patterns made sense just as using four-bit  hexadecimal notation makes 
sense if you are using 8 or any other multiple of 2 for your byte.














-- 
Stuart


-- 
AccessD mailing list
AccessD at databaseadvisors.com
http://databaseadvisors.com/mailman/listinfo/accessd
Website: http://www.databaseadvisors.com