From: utzoo!decvax!harpo!ihps3!ihuxl!larry
Newsgroups: net.micro
Title: interupts
Article-I.D.: ihuxl.219
Posted: Thu Jul 15 11:02:16 1982
Received: Sat Jul 17 06:32:43 1982

Can anybody explain why interupts are so ignored in cp/m-type systems? 
Here at the Labs, I have often had to explain to people that MOST cpm
systems do not have interupts, that i/o is done by polling.  I have an
idea why this is this way -- in the "early days" (when the Altair first
came out) most people ran Altair BASIC [pre-Microsoft BASIC].  This
BASIC was ORG'ed at zero, so the restart locations weren't available. 
The BASIC was also operating system independent -- there was NO operting
system as there is now with cpm, so the BASIC did all the i/o console,
and cassette tape (did it do the disk too?).  In anycase, since it did
polled i/o, that seemed to set the stage for the rest of the "world". 

	Anybody else have any ideas?

			Larry Marek
			 Bell Labs
			  Naperville, Il.