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CP/M Users

Midwinter

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Joined
Jan 26, 2009
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14
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Arizona - USA
I am new to CP/M and don't know a lot about it.

Am I correct in saying that there can be up to 15 user numbers?

Also to have compatibility between different machines do the files have to be created by user 0?

I appreciate everyone's help!
 

Chuck(G)

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Jan 11, 2007
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Depends on the version. MP/M specifies user areas of 0-15, but CP/M 2.x specifies that they're from 0 to 31. And QX-10 Valdocs used user area 96 to store its files. The enforcement in CP/M and MP/M is a simple mask in the Get?Set User Area system call.

Why area and not number? Because CP/M is essentially single-user. All the user area does is add another "character" to the file name in the directory to further qualify the name. Nothing very sophisticated at all. MP/M, on the other hand, is multi-user and does associate a user console with a user area.

As far as interchangeability among systems, there's a lot more to interchange that involves how the diskettes are formatted and laid out. I suspect that there were somewhere around 1000 variations on disk formatting and layout for CP/M.

As far as I'm aware, the only "standard" CP/M format was 8", single-density, single-sided, 26 sectors of 128 bytes at a 6:1 logical interleave with the first two tracks reserved for system use--the original "A1" format.
 

Terry Yager

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May 1, 2003
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Saginaw, MI, USA 48601
I am new to CP/M and don't know a lot about it.

Am I correct in saying that there can be up to 15 user numbers?

Sixteen, actually. Zero (0) counts.
Also to have compatibility between different machines do the files have to be created by user 0?

No, files can be exchanged from disk to disk and/or user to user, regardless of which user 'owns' the file, since there is no provision for security among different users.
I appreciate everyone's help!

You can save yourself a lot of grief by getting a program called NSWEEP, which makes the whole file exchange process a lot less painful than bashing your head against PIP.COM's syntax and multiple parameters.

--T
 
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Terry Yager

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As far as I'm aware, the only "standard" CP/M format was 8", single-density, single-sided, 26 sectors of 128 bytes at a 6:1 logical interleave with the first two tracks reserved for system use--the original "A1" format.

...and 70 tracks. AKA, 'IBM' Format, 'Exchange' Format, 'Distribution' Format, etc.

--T
 

Chuck(G)

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...and 70 tracks. AKA, 'IBM' Format, 'Exchange' Format, 'Distribution' Format, etc.

--T

Actually, 77 tracks...

Gary Kildall claimed that this was the standard format. Indeed, if you were an OEM, that's how you got your distro kit. If there was an OS to be booted, it was configured for an Intel MDS.

At least in MP/M, 0 was specified as the "system" area, so there were really only 15 "user" areas--or 31, or whatever.
 

CP/M User

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May 2, 2003
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Back of Burke (Guday!), Australia
Terry Yager wrote:

You can save yourself a lot of grief by getting a program called NSWEEP, which makes the whole file exchange process a lot less painful than bashing your head against PIP.COM's syntax and multiple parameters.

I dispute that because NSWEEP is so fiddley you might as well setup your PIP.COM or PIP.CMD so you can access it from any User Area - and once that's done there's nothing wrong with PIP!

Real CP/M Users know how the Command Line functions! :-D
 
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