[comp.sys.misc] binary data files

peter@ficc.uu.net (Peter da Silva) (05/09/89)

In article <1970@dataio.Data-IO.COM>, bright@Data-IO.COM (Walter Bright) writes:
> And CPM is based on DEC's RT-11 for PDP-11 computers. At the time, DEC
> operating systems were very popular, and they all used the \r and \n
> convention.

That's funny... most DEC systems I know (including RSX, which is what CP/M
seems most closely modelled on) store files as a series of variable length
records containing (usually) a 2 or 4 byte header containing the length and
maybe the line number and then the data on the line.

CP/M was actully based directly on an obscure intel DOS called Isis, with
some teminology (PIP, etc) borrowed from DEC.

Isn't this getting a bit far from 'C'?
-- 
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guy@auspex.auspex.com (Guy Harris) (05/10/89)

>That's funny... most DEC systems I know (including RSX, which is what CP/M
>seems most closely modelled on) store files as a series of variable length
>records containing (usually) a 2 or 4 byte header containing the length and
>maybe the line number and then the data on the line.

There are zillions of DEC OSes; they're similar in some realms, and
different in others.  Whilst they have similar flavors of
command languages (both the old-style "run PIP and then type
outputfile=inputfile at its prompt" type and the new-style DCL type),
they have different text file formats.  RSX-11 and VMS use the IBMish
variable-length record format, but others (RT-11 being one, and possibly
TOPS-10 as well) use the CR/LF at the end format.  I don't know of any
others offhand that use the Files-11/RMS format.

jms@doctor.Tymnet.COM (Joe Smith) (05/16/89)

In article <4122@ficc.uu.net> peter@ficc.uu.net (Peter da Silva) writes:
>In article <1970@dataio.Data-IO.COM>, bright@Data-IO.COM (Walter Bright) writes:
>> And CPM is based on DEC's RT-11 for PDP-11 computers. At the time, DEC
>> operating systems were very popular, and they all used the \r and \n
>> convention.
>
>That's funny... most DEC systems I know (including RSX, which is what CP/M
   I have to disagree with this statement ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>seems most closely modelled on) store files as a series of variable length
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>records containing (usually) a 2 or 4 byte header containing the length and
>maybe the line number and then the data on the line.
>
>CP/M was actully based directly on an obscure intel DOS called Isis, with
>some teminology (PIP, etc) borrowed from DEC.
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^    agreed
>Peter da Silva, Xenix Support, Ferranti International Controls Corporation.

TOPS-10, TOPS-20, OS/8, RT11, RSTS all use CR+LF.
Only 2 systems, RSX and VMS use variable length records.

History: The PDP-6 evolved into the PDP-10 which runs TOPS-10.  Between the
PDP-6 and the PDP-11 the PDP-8 was invented, running OS/8.  Then came the
PDP-11.  RT-11 looks very much like TOPS-10 scaled down for a single user.
RSTS-11 is a multiuser system that originally had the system utilities
written in interpreted BASIC.  Then came RSX, which uses RMS (Record Management
System) for variable length records without CRLF.  Based on what came before
RSX, I'd say CP/M was NOT based on RSX.

When you count the number of different _Operating_Systems_ DEC has, the
majority use CR+LF.  However, the count of installed systems that use an OS
with RMS is a different story.

This whole topic is irrelevant anyway!  :-)
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