288 lines
19 KiB
HTML
288 lines
19 KiB
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<meta name="DC.Title" content="VTxxx full screen considerations" />
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<meta name="abstract" content="You should be aware of the considerations when using VTxxx emulation." />
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<meta name="description" content="You should be aware of the considerations when using VTxxx emulation." />
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<meta name="DC.Relation" scheme="URI" content="rzaiwmanagevtxxx.htm" />
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<meta name="DC.Relation" scheme="URI" content="rzaiwstrtvtxxxsession.htm" />
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<title>VTxxx full screen considerations</title>
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</head>
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<body id="rzaiwvtxxxconsiderations"><a name="rzaiwvtxxxconsiderations"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">VTxxx full screen considerations</h1>
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<div><p>You should be aware of the considerations when using VTxxx emulation.</p>
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<p>As with any emulation type, you should be aware of certain considerations
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before using the VTxxx full-screen mode with your Telnet Server. These considerations
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include security concerns as well as possible error conditions and indicator
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lights. Become familiar with these considerations to better understand how
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to use VTxxx full-screen mode.</p>
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<p>In addition to security concerns, there are many other concerns to consider
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before using VTxxx full-screen mode with your Telnet server. When using VTxxx
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full-screen mode, you should be aware of the following concerns:</p>
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<ul><li><a href="#rzaiwvtxxxconsiderations__SECCONCERNS">Security considerations for VTxxx full-screen mode</a></li>
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<li><a href="#rzaiwvtxxxconsiderations__PASSTHRU">Telnet and SNA 5250 pass-through considerations for VTxxx full-screen mode</a></li>
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<li><a href="#rzaiwvtxxxconsiderations__REQPROCESSING">System request processing for VTxxx sessions</a></li>
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<li><a href="#rzaiwvtxxxconsiderations__ERRORCOND">Error conditions on 5250 keyboard</a></li>
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<li><a href="#rzaiwvtxxxconsiderations__VTXXXDISPSTATION">Display stations and VTxxx support</a></li>
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<li><a href="#rzaiwvtxxxconsiderations__SPTOPDIFF">Operational differences</a></li>
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<li><a href="#rzaiwvtxxxconsiderations__SPTKEYCHAR">Keyboard characteristics</a></li>
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<li><a href="#rzaiwvtxxxconsiderations__SPTSCHAR">Screen characteristics</a></li>
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<li><a href="#rzaiwvtxxxconsiderations__SPTVSS">VTxxx screen size</a></li>
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<li><a href="#rzaiwvtxxxconsiderations__SPTVCA">VTxxx character attributes</a></li>
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</ul>
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<div class="section" id="rzaiwvtxxxconsiderations__SECCONCERNS"><a name="rzaiwvtxxxconsiderations__SECCONCERNS"><!-- --></a><h4 class="sectiontitle">Security considerations for VTxxx full-screen
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mode</h4><p>The number of sign-on attempts allowed increases if Telnet
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automatically configures virtual devices. The number of sign-on attempts is
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equal to the number of system sign-on attempts allowed multiplied by the number
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of virtual devices possible.</p>
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<p>The QMAXSIGN system value defines the number
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of system sign-on attempts allowed. The QAUTOVRT system value defines the
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number of virtual devices Telnet can create.</p>
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</div>
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<div class="section" id="rzaiwvtxxxconsiderations__PASSTHRU"><a name="rzaiwvtxxxconsiderations__PASSTHRU"><!-- --></a><h4 class="sectiontitle">Telnet and SNA 5250 pass-through considerations
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for VTxxx full-screen mode</h4><p>The iSeries™ server supports 5250 pass-through.
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5250 pass-through is similar to Telnet, but runs on an Systems Network Architecture
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(SNA) protocol network rather than a TCP/IP network. 5250 pass-through uses
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virtual displays to direct output to the physical devices just as Telnet does.
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In 5250 pass-through, the iSeries server automatically creates virtual devices
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in the same way as it does for Telnet. Therefore, the Devices System Value
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controls the number of automatically configured virtual devices for both 5250
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pass-through and Telnet.</p>
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</div>
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<div class="section" id="rzaiwvtxxxconsiderations__REQPROCESSING"><a name="rzaiwvtxxxconsiderations__REQPROCESSING"><!-- --></a><h4 class="sectiontitle">System request processing for VTxxx sessions</h4><p>The
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system request processing for the VTxxx sessions is slightly different than
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that for a normal 5250 workstation.</p>
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<p>When the System Request key is pressed
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on a 5250 workstation, a system request command line appears at the bottom
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of the display. If you press the Enter key, the System Request menu appears.</p>
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<p>For
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VTxxx sessions when you call the system request function, the System Request
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menu displays immediately.</p>
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</div>
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<div class="section" id="rzaiwvtxxxconsiderations__ERRORCOND"><a name="rzaiwvtxxxconsiderations__ERRORCOND"><!-- --></a><h4 class="sectiontitle">Error conditions on 5250 keyboard</h4><p>Certain
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error conditions cause a 5250 keyboard to lock and an error code to display
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on the message line. An example of such a condition is typing when the cursor
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is not in an input field. For VTxxx sessions, these errors cause a bell to
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sound on the VTxxx workstation and the keyboard to remain unlocked.</p>
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<p>Certain iSeries applications
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also lock the 5250 keyboard and turn on the 5250 input-inhibited light. The
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user must press the Error Reset key before the keyboard unlocks. For VTxxx
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sessions, the locking of the 5250 keyboard causes a bell to sound on the VTxxx
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terminal whenever a key is pressed. To unlock the keyboard, the VTxxx key
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that is mapped to the Error Reset key must be pressed. In the default VTxxx
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keyboard map, the CTL-R key maps to the Error Reset key.</p>
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</div>
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<div class="section" id="rzaiwvtxxxconsiderations__VTXXXDISPSTATION"><a name="rzaiwvtxxxconsiderations__VTXXXDISPSTATION"><!-- --></a><h4 class="sectiontitle">Display stations and VTxxx support</h4><p>When
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the system negotiates VTxxx support, the Telnet server transmits screens that
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are a maximum of 24 rows by 80 columns. The VTxxx client system sees these
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screens in much the same way as they appear on a 5251 Model 11 workstation.
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However, there are some differences.</p>
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<p>A 5251 workstation has indicator
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lights on the right side that indicate: System Available, Message Waiting,
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Keyboard Shift, Insert Mode, and Input-Inhibited.</p>
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<p>The VTxxx server support
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emulates the System Available light by putting an asterisk in column 80 of
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row 9. For Message Waiting, Insert Mode, and Input-Inhibited lights, the asterisk
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appears in column 80 of rows 11, 13, or 15. When an asterisk appears, the
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asterisk overwrites the character that was previously displayed at that screen
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location. By default, the VTxxx server does not display the indicator lights.
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You can enable or disable these indicators by typing the key sequence that
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is mapped to the toggle indicator lights function. The default key sequence
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for this function is ESC-T.</p>
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<div class="note"><span class="notetitle">Notes:</span> <ul><li>When using a VTxxx client to attach to the iSeries Telnet server, note that the
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Insert Mode and the Input-Inhibited lights might not always display as described
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above. 5250 supports the attachment as a local function while the VTxxx has
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no such facility. The System Available and Message Waiting indicators, however,
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will display correctly.</li>
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<li>A 5251 display supports a screen attribute known as a column separator.
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The <span class="uicontrol">column separator</span> is a vertical line displayed between
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characters. This line does not take up a character space. The VTxxx does not
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support such an attribute. If an iSeries application generates a screen
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that uses the column separator attribute, that screen is displayed on the
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VTxxx client system with the column separator mapped to the VTxxx underline
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attribute.</li>
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</ul>
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</div>
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</div>
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<div class="section" id="rzaiwvtxxxconsiderations__SPTOPDIFF"><a name="rzaiwvtxxxconsiderations__SPTOPDIFF"><!-- --></a><h4 class="sectiontitle">Operational differences</h4><p>As an iSeries Telnet
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user, you should be aware of physical and operational differences between
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VTxxx and 5250 terminals.</p>
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<p>The 5250 is a block mode terminal. Data typed
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on a 5250 is accumulated in a buffer and only sent to the iSeries server
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when an AID (attention identifier) key ispressed. An AID key on a 5250 keyboard
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is a key that initiates a function. The following list shows the AID keys
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on a 5250 keyboard:</p>
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<ul><li>Clear</li>
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<li>Command Function 1 through 24</li>
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<li>Enter/Rec Adv</li>
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<li>Help</li>
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<li>Print</li>
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<li>Record Backspace Function</li>
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<li>Roll Down (Page Up)</li>
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<li>Roll Up (Page Down)</li>
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</ul>
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<p>VTxxx terminals operate in a character mode. Characters transmit immediately
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to the host when a key is pressed.</p>
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<p>Another difference is the way the
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data arrives on the display. The system writes data to a VTxxx terminal one
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character at a time, and you see the data arrive as streams of characters.
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With the 5250, the system writes data in blocks, and all or part of the display
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changes at once.</p>
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</div>
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<div class="section" id="rzaiwvtxxxconsiderations__SPTKEYCHAR"><a name="rzaiwvtxxxconsiderations__SPTKEYCHAR"><!-- --></a><h4 class="sectiontitle">Keyboard characteristics</h4><p>You should
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avoid using the 5250 cursor movement keys. Instead, you should use the function
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keys associated with the *CSRUP, *CSRDOWN, *CSRRIGHT, and *CSRLEFT keywords.
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By default these are keys F13, F14, F15, and F16. If you use the 5250 cursor
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movement keys, the VTxxx application you are using might not function as expected.
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This is because the results of using these keys do not transmit to the remote
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system until an attention identifier (AID) key is pressed.</p>
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<p>For example,
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using Telnet to the RS/6000<sup>®</sup> and obtaining VT220 emulation, the SMIT command
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provides a menu driven interface to AIX<sup>®</sup>. Here the function keys associated with
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*CSRxx keywords perform as you will expect the cursor movement keys to do.
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However, the 5250 cursor movement keys, while physically moving the cursor
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down the screen and correctly selecting the SMIT option, do not cause the
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selected option to be highlighted. The highlighting in reverse image remains
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with the first option on the SMIT menu, regardless of the key position.</p>
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<p>Typing
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a control character on an iSeries keyboard is different than typing a control
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character on an actual VTxxx terminal. On a VTxxx terminal, press and hold
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down the control key while pressing the character associated with the control
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function.</p>
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<p>When using the iSeries Telnet support, the equivalent
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is achieved by typing a 2 character control indicator followed by pressing
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the function key associated with the Send without Carriage Return (*SENDWOCR)
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default function (the F11 key). For example, if the default keyboard map and
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the default STRTCPTELN command parameters are in effect, the VTxxx Control-C
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function can be entered by typing &C followed by pressing the F11 key.
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<F12> can also enter this function, using the default keyboard map. In
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case you are using an application where <F12> is remapped, this example
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is included, and illustrates the principle of the *SENDWOCR key.</p>
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<p>Use
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the CTLCHAR parameter of the STRTCPTELN command to select the character used
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to indicate a control character. The default is &. The &C characters
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must be the last characters typed before pressing the *SENDWOCR function key
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or the &C is not interpreted as a control character. A control character
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only transmits when the *SENDWOCR function key is pressed. You can assign
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frequently used VTxxx control characters to a function key. The following
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is a descriptive example of the Ctrl-C command. When using a Telnet client
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to connect to an RS/6000 system, the system typically negotiates VT220
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emulation. The Ctrl-C sequence is an important one in AIX to end long running commands, such as
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PING. It is, therefore, important that you know how to do this before issuing
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any RS/6000 commands.
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By default the sequence is &C<F11>. Note that you need to enter these
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keys quickly, and it might take several attempts before the RS/6000 task
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accepts the input.</p>
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<p>Press function key that is associated with the *HIDE
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function, (F6 on the default keyboard map) if you do not want to display the
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typed characters. Use this function when typing a password.</p>
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<p>If you want
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the characters that have been typed to be sent to the remote system for processing
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without pressing the Enter key, you should press the function key associated
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with the *SENDWOCR function (F11 on the default keyboard map).</p>
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<p>It is
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often useful to be able to recall previously entered commands. On the iSeries server,
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F9 often provides this function. On AIX, this can be activated by typing the
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command <samp class="codeph">set -o vi</samp> and pressing Enter. After this, you can
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start retrieving commands with the sequence Esc-K. To perform this sequence
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using the default keyboard map while in VTxxx emulation, you should usethesequence
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<F5>k<F11>. The Esc character starts the command retrieval. Then use
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the k to retrieve further commands. While operating in this mode, the commands
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H for right, L for left, X for delete, I for insert, and R for replace apply.
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The sequence<F5>i<F11> switches this facility off.</p>
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</div>
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<div class="section" id="rzaiwvtxxxconsiderations__SPTSCHAR"><a name="rzaiwvtxxxconsiderations__SPTSCHAR"><!-- --></a><h4 class="sectiontitle">Screen characteristics</h4><p>The character
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in the position just before the cursor position will always be blank. The
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actual character saves internally and shows when the display refreshes with
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the cursor in a different position.</p>
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<p>A VTxxx application that uses row
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1, column 1 of the display does not work the same when using iSeries Telnet
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client support. Most 5250-type display stations do not allow input to row
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1, column 1. If the VTxxx application positions the cursor at row 1, column
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1, the iSeries server
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puts the cursor at row 1, column 2 automatically.</p>
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<p>Due to architectural
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differences, the system ignores certain unsupported commands or sequences.
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An example is downstream loadable character sets.</p>
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</div>
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<div class="section" id="rzaiwvtxxxconsiderations__SPTVSS"><a name="rzaiwvtxxxconsiderations__SPTVSS"><!-- --></a><h4 class="sectiontitle">VTxxx screen size</h4><p>Telnet VTxxx full-screen
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mode supports the following screen sizes:</p>
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<ul><li>On 3180 display stations: <ul><li>24 x 80 VTxxx screens should display as 24 x 80.</li>
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<li>24 x 132 VTxxx screens should display as 24 x 132.</li>
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</ul>
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</li>
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<li>On 5250 display stations: <ul><li>24 x 80 VTxxx screens should display as 24 x 80.</li>
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<li>24 x 132 screens require the function key assigned to *SHIFTDSP (F10 on
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the default keyboard map) to move the information about the screen right or
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left.</li>
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</ul>
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</li>
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</ul>
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</div>
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<div class="section" id="rzaiwvtxxxconsiderations__SPTVCA"><a name="rzaiwvtxxxconsiderations__SPTVCA"><!-- --></a><h4 class="sectiontitle">VTxxx character attributes</h4><p>A VTxxx terminal
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supports the following attributes:</p>
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<ul><li>Blink</li>
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<li>Bold</li>
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<li>Reverse image</li>
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<li>Underline</li>
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<li>Any combination of the above</li>
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</ul>
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<p>The 5250 data stream supports the previous attributes so that a 5250
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display station can represent all of the VTxxx attributes. However, there
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are some limitations:</p>
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<ul><li>The 5250 data stream can only support three of the character attributes
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at the same time. The underline, blink, and reverse image attributes display
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when the remote system selects all the VTxxx attributes at the same time.
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A 5250 display station cannot display the combination of underline, bold,
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and reverse image. Underline and reverse image displays when a VTxxx application
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selects this combination.</li>
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<li>The attribute byte takes up a space on the 5250 display stations that
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do not support extended attributes. Attributes do not take up space on a VTxxx
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terminal. This means that if you select character attributes, you do not see
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all of the data shown on the 5250 display. When receiving VTxxx data that
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is to display with character attributes, the 5250-attribute byte overlays
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the position before the data. The character that was displayed there is lost.
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If a character is to display in row 1, column 1 with the attributes set, that
|
||
|
|
character is not displayed. You can choose not to have the character attributes
|
||
|
|
displayed by specifying DSPCHRATTR(*NO) on the STRTCPTELN command. This allows
|
||
|
|
you to see all of the data on the display without attributes.</li>
|
||
|
|
</ul>
|
||
|
|
<div class="note"><span class="notetitle">Note:</span> This restriction is not applicable for displays that support extended
|
||
|
|
attributes such as the 3477 display.</div>
|
||
|
|
</div>
|
||
|
|
<div class="section"><h4 class="sectiontitle">VT100 keyboard indicator</h4><p>A VT100 terminal has a
|
||
|
|
L1 indicator that can be programmed for different applications. This indicator
|
||
|
|
is not emulated by the iSeries Telnet support.</p>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<div>
|
||
|
|
<div class="familylinks">
|
||
|
|
<div class="parentlink"><strong>Parent topic:</strong> <a href="rzaiwmanagevtxxx.htm" title="VTxxx Telnet client sessions provide information on using this emulation type to sign on and use applications on a remote system that has a Telnet server application. This section also provides more information on VTxxx emulation.">VTxxx Telnet client sessions</a></div>
|
||
|
|
</div>
|
||
|
|
<div class="relconcepts"><strong>Related concepts</strong><br />
|
||
|
|
<div><a href="rzaiwstrtvtxxxsession.htm" title="You can start a Telnet client session using VTxxx emulation.">Start a VTxxx Telnet client session</a></div>
|
||
|
|
<div><a href="rzaiwdetprobtelnet.htm" title="You can read this topic for diagnostic information, including a flow chart for server problem analysis, and a list of materials needed when reporting Telnet problems.">Determine problems with Telnet</a></div>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
</body>
|
||
|
|
</html>
|