Appendix D. 3276 Switches; Switches Al-A8: Sdlc Address Switches; Loop Adapter Feature Machines ) - IBM 3270 Manual

Appendix D. 3276 Switches
Note: To be effective, switches must be set when 32 76 power is off Changing a switch
position when power
is
on has no effect. Exceptions: Primary Line Speed/Secondary Line
Speed and SNBU switches may be changed while power is on.
This appendix describes only the switches associated with matching the 3276 to the host
system and to the communication facilities; operational switches are not included.
Instructions for completing the 3276 Switch Settings Form (at the end of this appendix)
are included in each description. It is recommended that the planner:
1. Review all switch descriptions and determine the correct setting for all applicable
switches.
2. Enter the switch settings on the form.
3. Cross out all form entries that are not needed.
4. Supply the completed form to the 3276 setup personnel.
Switches Al - A8: SDLC Address Switches
These eight switches (labeled "A" on the control panel) are set to correspond to the
SDLC control unit address of the 3276. When the 3276 has the SDLC/BSC Switch
feature, the "A" switches are effective when the SDLC/BSC switch is set to SDLC; the
settings of the "A" switches are therefore important if SDLC line control is used.
However, if you wish to switch alternately between SDLC and BSC line control, both the
"A" and "B" switches must be set to correspond to the correct addresses.
To determine the "A" switch settings, first obtain the control unit address (in
hexadecimal) from the system programmer. Then use the chart in Figure D-1 to find the
"A" switch (SDLC Address switch) settings. A "l" in the figure represents a switch set to
ON; a "O" represents a switch set to OFF. For example, a control unit address of
hexadecimal 02 requires that switches Al through A6 and switch A8 be set to OFF and
switch A7 to ON.
In Figure D-1, note that hexadecimal addresses 30 through EO are bracketed. To
determine the switch settings for control unit address C8, for example, first find address
CO. Address CO requires that switches Al and A2 be set to ON and switches A3 and A4
to OFF. Next, find address 08. Address 08 requires that switch AS be set to ON and
switches A6, A7, and A8 to OFF.
Item 1 in the example of a completed 3276 Switch Settings Form (Figure D-6, at the end
of this appendix) shows how the form should be filled in for SDLC address C8. Fill in
item 1 on the form.
Switches Bl - BS: BSC Control Unit Address Switches (Except Loop Adapter Feature Machines)
These five switches (labeled "B" on the control panel) are set to correspond to the BSC
control unit address of the 3276. When the 3276 has the SDLC/BSC Switch feature, the
"B" switches are effective when the SDLC/BSC switch is set to BSC; the settings of the
"B" switches are therefore important if BSC line control is used. However, if you wish to
switch alternately between SDLC and BSC line control, both the "A" and "B" switches
must be set to correspond to the correct addresses.
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