Intermec CV30 Intermec Terminal Emulator (ITE) Programmer's Reference Manual - Page 22

Chapter 1 - About 3270 and 5250 Programming Set Buffer Address (SBA) The 3-byte SBA order specifies a new buffer address which operations are to start or continue. Operations start at address 0 by default. Use the SBA order to: • write data into various areas of the buffer. • precede another order in the data stream to specify the starting address for a PT, RA, or EUA order. • specify the address at which an attribute byte is stored by an SF order. • specify the cursor address for an IC order. If the SBA order specifies an invalid address (that is, an address outside the range of the computer display buffer) the following events occur: 1 The write operation is terminated at that point. 2 The computer recognizes this as an error condition. 3 The computer automatically performs a clear memory operation. 4 The entire display buffer is set to nulls. 5 A clear AID character is transmitted to the computer control unit for forwarding to the host. The result is the same as if the user had selected Function 7 (clear memory). Start Field (SF) This order notifies the computer that the next byte in the write data stream is an attribute character. The computer stores the next byte and attribute character at the current buffer address. As the attribute character is stored, the computer sets a control bit at the address, identifying that byte as an attribute character during subsequent program or device operations with the buffer data. Note: The byte immediately following the SF order in the data stream is always stored as an attribute character even when the byte is intended as an order or an alphanumeric data character. The attribute character defines the characteristics or "attributes" of the data that follows. Each attribute character plus all the data following it, up to the next attribute character or the last location of the buffer, is called a field. In addition to defining the start of a field, attribute characters define these characteristics for all character locations contained within the field: • Protected from modification by the user, or unprotected (available for the operator to modify or enter data). If unprotected, the field is an input field. • Alphanumeric (a field that accepts alphabetic, numeric, or symbol characters) or numeric (an input field that accepts only the period, dash, and numbers 0 to 9). • Field displayed or not displayed to the user. Each character occupies one of the character locations in the buffer, but cannot display. During display operations, attribute characters appear as blanks. 10 Intermec Terminal Emulator (ITE) Programmer's Reference Manual