DOS backward compatibility.

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   Are DOSes (either MS- or IBM PC) 100% backward compatible? Or at least any versions of them?

In other words, will absolutely everything running on PC DOS 1.0 run on PC DOS 6.22? 

I know they are "highly" backward compatible, but question is if it's an absolute 100% compatibility or not?

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Shador Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 07 January 2012 Online Status: Offline Posts: 36	Quote Reply Topic: DOS backward compatibility. Posted: 11 March 2012 at 11:32am
	Are DOSes (either MS- or IBM PC) 100% backward compatible? Or at least any versions of them? In other words, will absolutely everything running on PC DOS 1.0 run on PC DOS 6.22? I know they are "highly" backward compatible, but question is if it's an absolute 100% compatibility or not?

Mike Newcomb Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 15 July 2006 Location: London UK Online Status: Offline Posts: 528	Quote Reply Posted: 11 March 2012 at 12:28pm
	Hi Shador, you just have to try what ever application or program you want to run and see if it works ok. Early dos ran on early machines and programs written for such were not necessarily FORWARD compatible. e.g. a program may not have a time control and would then run far too fast on a later pc. When Turbo XT's appeared, many had a switch to slow down to the normal speed (4.77mhz?) to overcome this. Some could be switched inflight and others only on loading. Good Luck - Mike Edited by Mike Newcomb - 11 March 2012 at 12:35pm

Shador Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 07 January 2012 Online Status: Offline Posts: 36	Quote Reply Posted: 11 March 2012 at 2:31pm
	CPU speed compatibility is out of scope here because DOS has nothing to do with it. I'm asking specifically about DOS functions and all DOS-related stuff. Also, let's assume we're talking about perfect experiment and different DOSes are run on the same computer.