Editing Peripheral Interchange Program

{{short description|File transfer utility}}
{{More citations needed|date=July 2009}}
{{Infobox software
| name                   = Peripheral Interchange Program (PIP)
| logo                   = 
| screenshot             = 
| screenshot size        = 
| caption                = 
| author                 = [[Digital Equipment Corporation]] / Harrison "Dit" Morse
| developer              = [[Digital Research]] / [[Gary Kildall]], [[Heath Company]]
| released               = {{Start date and age|1960s}}
| latest release version = 
| latest release date    = 
| operating system       = [[DEC BATCH-11/DOS-11|BATCH-11/DOS-11]], [[RT-11]], [[RSTS/E]], [[RSX-11]], [[OS/8]], [[TOPS-10]], [[TOPS-20]], [[CP/M]], [[MP/M]], [[DOS Plus]], [[HDOS]], [[OpenVMS|VMS]]
| genre                  = [[Command (computing)|Command]]
| license                = 
| website                = 
}}
'''Peripheral Interchange Program''' ('''PIP''') was a utility to transfer files on and between devices on [[Digital Equipment Corporation]]'s computers. It was first implemented on the [[PDP-6]] architecture by Harrison "Dit" Morse early in the 1960s.  It was subsequently implemented for DEC's operating systems for [[PDP-10]], [[PDP-11]], and [[PDP-8]]<ref>[https://www.grc.com/pdp-8/docs/OS8_System_Reference_Manual.pdf OS/8], ''OS/8 System Reference Manual''</ref> architectures.
In the 1970s and 1980s [[Digital Research]] implemented PIP on [[CP/M]]<ref>[http://www.tramm.li/i8080/cpm22-m.pdf CP/M], ''CP/M Operating System Manual''</ref>  and [[MP/M]].<ref>[http://www.cpm.z80.de/manuals/mpm2ug.pdf MP/M], ''MP/M Operating System User's Guide''</ref>

==History==
It is said that during development it was named ATLATL, which is an acronym for "Anything, Lord to Anything, Lord."<ref>[http://www.jargon.net/jargonfile/p/PIP.html PIP], ''The [[Jargon File]]''</ref>  This humorously described both its purpose as a device-independent [[file copying]] tool and the difficulties at the time of safely copying files between devices.

The original PIP syntax was

 PIP destination←source /switches

using the left-arrow character from the [[ASCII]]-1963 character set that the [[Friden Flexowriter|Flexowriter]] keyboards of the time used.  As other terminals were introduced that used later versions of ASCII (without the left-arrow character), PIP allowed the syntax

 PIP destination=source

The [[underscore]] ([[Underscore|_]]) character, which was in the same ASCII character position that left-arrow had occupied, was still supported to separate the destination and source specifications.

Source and destination were ''file specification'' strings.  These consisted of a device name, typically 2 characters for device type such as DK (disk), LP (line printer), MT (magnetic tape), etc. and a unit number from 0 to 7, a colon (:), filename and extension.

Copying was generally permitted between any file specification to any other where it made sense.

Early versions of [[VAX/VMS]] implemented certain [[DIGITAL Command Language|DCL]] commands, such as [[Directory (OpenVMS command)|DIRECTORY]] and [[ren (command)|RENAME]], by running [[RSX-11M]] PIP in compatibility mode. This usage of PIP was replaced by VAX-specific code in VAX/VMS 2.0,<ref>{{cite web|url=http://www.bitsavers.org/pdf/dec/vax/vms/2.0/AA-D015C-TE_VAX_VMS_2.0_Release_Notes_198003.pdf|title=VAX/VMS Release Notes Version 2.0}}</ref> but PIP remained as part of the VAX-11 RSX layered product for VMS.<ref>{{cite web|url= https://manx-docs.org/collections/antonio/dec/aedl72cte.pdf|title=VAX-11 RSX Software Product Description}}</ref>

As late as the mid-1980s, PIP was still in common use on [[TOPS-10]], [[TOPS-20]] and [[PDP-11]] systems.

==PIP in CP/M and MP/M==
[[File:CPM-86.png|thumb|<code>PIP.CMD</code> in [[CP/M-86]]]]
[[File:Digital Research DOS Plus Version 1.2 720x400.png|thumb|Example using the <code>PIP</code> command in [[DOS Plus]] to create a text file from {{tt|CON:}} console input]]
[[Gary Kildall]], who developed [[CP/M]] and [[MP/M]], based much of the design of its file structure and command processor on operating systems from Digital Equipment, such as [[RSTS/E]] for the PDP-11. Besides accessing files on a [[floppy disk]], the PIP command in CP/M could also transfer data to and from the following "special files":
*{{tt|CON:}} — [[System console|console]] (input and output)
*{{tt|AUX:}} — an auxiliary device. In CP/M 1 and 2, PIP used {{tt|PUN:}} (paper tape punch) and {{tt|RDR:}} (paper tape reader) instead of {{tt|AUX:}}
*{{tt|LST:}} — list output device, usually the [[computer printer|printer]]
*{{tt|PRN:}} — as {{tt|LST:}}, but lines were numbered, tabs expanded and form feeds added every 60 lines
*{{tt|[[Null device|NUL:]]}} — null device, akin to [[Null device|\Device\Null]] and [[Null device|/dev/null]]
*{{tt|EOF:}} — input device that produced [[end-of-file]] characters, [[ASCII]] {{tt|0x1A}}
*{{tt|INP:}} — custom input device, by default the same as {{tt|EOF:}}
*{{tt|PUN:}} — punch card unit:
*{{tt|OUT:}} — custom output device, by default the same as {{tt|NUL:}}

These were not true [[device file]]s, however, because their handling was limited to PIP. The two custom devices {{tt|INP:}} and {{tt|OUT:}} were implemented as calls to fixed locations at the start of the PIP program; the intention was that the user, or the [[Original Equipment Manufacturer|OEM]], could [[Software patch|patch]] these locations to add their own input or output devices. 246 bytes of free space were left in the program for this purpose.

In addition to the usual <code>PIP destination=source</code> syntax, PIP under CP/M still allowed the old <code>PIP destination_source</code> form. This behaviour was not documented, and CP/M generally did not have a standard for which characters could appear in file names; therefore other programs could and did create filenames containing underscore characters, which PIP could not handle.

==Reserved filenames in Microsoft Windows==
The PIP program is the reason for [https://learn.microsoft.com/en-us/windows/win32/fileio/naming-a-file#naming-conventions reserved filenames] in Microsoft Windows: <code>CON</code> <code>PRN</code> <code>AUX</code> <code>NUL</code> <code>COM0</code> <code>COM1</code> <code>COM2</code> <code>COM3</code> <code>COM4</code> <code>COM5</code> <code>COM6</code> <code>COM7</code> <code>COM8</code> <code>COM9</code> <code>LPT0</code> <code>LPT1</code> <code>LPT2</code> <code>LPT3</code> <code>LPT4</code> <code>LPT5</code> <code>LPT6</code> <code>LPT7</code> <code>LPT8</code> <code>LPT9</code>. This limitation is case-insensitive, and also applies to basenames. So for example, <code>Con.txt</code> is an invalid filename.

==See also==
*[[copy (command)]] – RT-11, RSX-11, OpenVMS, AmigaOS, DOS, OS/2 and Microsoft Windows command for copying data
*[[cp (Unix)]] – Unix command for copying data
*[[Kermit (protocol)]]

==References==
{{Reflist}}

{{Digital Research}}

[[Category:CP/M software]]
[[Category:File copy utilities]]