Editing IBM 3270 PC (section)

== Operating Environment ==

The 3270 PC runs '''PC DOS 2.0 or 2.1''' overlaid with the '''3270 PC Control Program''':

* '''Up to 4 mainframe sessions''' running concurrently.
* '''1 DOS task''' running concurrently with the mainframe sessions (only one DOS task can be active at a time).
* '''2 notepads''' for cross-session text manipulation.
* All seven of these contexts visible in a '''windowed display''' on the 5272 monitor.

''PC Magazine'' (January 1985) called the Control Program "a memory hog" — it consumes approximately 200 KB resident, leaving limited free RAM for DOS applications.

'''Control Program v3.0''' is required for the 1986 Models 31/51/71 and all P-models.

In '''1987''' the '''3270 Workstation Program''' (IBM '''84X0982''') replaced the Control Program, providing the same multi-session experience on a standard XT or AT with only a 3278/79 Emulation Adapter — and adding DOS 3.3 support plus up to six DOS sessions.<ref name="wsp87">IBM, ''3270 Workstation Program Version 1.0 User's Guide and Reference'', 84X0982, April 1987, at <code>bitsavers.org/pdf/ibm/pc/3270/</code>.</ref>

=== File Transfer ===

The 3270 PC's stand-out practical capability is its '''SEND / RECEIVE file transfer''' between CMS (or TSO) on the mainframe and PC DOS on the workstation, with automatic '''EBCDIC↔ASCII conversion'''.