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3276nso Emulation Mode
READ COMMANDS. The HP 2625A supports two types of Read Commands. These com-
mands control the reading of data from the display.
• READ BUFFER - This command is primarily used in diagnostic tests. It initiates the
transfer of the entire display to the IBM host from the buffer position where reading begins
to the last buffer location in the display.
• READ MODIFIED -This command reads those fields where the MDT bit is set. Depending
upon which key you pressed to request this operation, the Read Modified Command in-
itiates one of two actions:
a) Read Modified--pressing the
ENTER
key, the
CURSOR SEL
key (when a ampersand is
the designator character), or a PF key transfers all modified fields to the program.
b) Short Read--pressing either the
CLEAR
key or one of the three
PA
keys transmits a code
signifying which one of these keys was pressed.
NOTE: As the Read Modified All Command only applies to a 3276 Control Unit operating in
SNAlSDLC protocol, your terminal offers no support for this command. Additionally,
the Test Request Read is initiated by pressing the
SYS REO
(System Request) key.
As the HP 2625A doesn't support this key, this command is also unsupported.
Refer to the IBM 3270 Information Display System Component Description manual for a
complete description of the control characters and data transmitted for the various Read
'~
Commands.
)
CONTROL COMMANDS. The 3270 system may execute four types of Control Commands.
The Select and No Operation Commands, however, are invalid for a 3276 Control Unit, and
the HP 2625A establishes its own procedure for copying information.
• ERASE ALL UNPROTECTED - This command erases all data within unprotected fields.
• COpy -This command transfers data between devices. The HP 2625A offers no support for
this command. (See the following discussion on ttpRINT OPERATIONS" for ways to obtain
printed copies with your HP 2625A.)
Orders
An IBM 3276 recognizes two types of orders: Buffer Control Orders and Printout Format
Orders. The following paragraphs summarize these orders. See the IBM 3270 Information
Display System Component Description manual for complete details on implementation.
BUFFER CONTROL ORDERS. Six types of buffer control orders facilitate the writing of
information to the display:
• START FIELD (SF) - The SF order notifies the terminal that the next byte in the data
stream is an attribute byte.
• SET BUFFER ADDRESS (SBA) -The SBA order specifies a new buffer address from which
write operations start or continue.
F-40
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