SCS DATA STREAMS | Page |
Transparent (TRN) — 35h
The Transparent command indicates the start of transparent data. This data is not scanned for SCS control codes. The command is followed by a count byte that indicates the number of bytes of transparent data to follow. The command has the following format:
(TRN)(CNT) Where:
TRN is the Transparent command code 35h.
CNT is a single binary byte denoting the number of bytes in the transparent block. The Count value does not include the count byte.
The Transparent command is especially important because it gives the user the ability to generate any possible 8 bit command or data byte to be output to the attached device. Many of the extended 8 bit ASCII command codes used by printers and plotters must be transmitted as transparent data streams because they cannot be generated or passed through the IBM system without being modified. Each byte of data is sent to the printer without translation. For example, the following 8 bit EBCDIC codes are the RESET command for a Xerox laser printer:
35031B2B58
35 is the transparent command code, 03 is the count of the data bytes to be sent to the attached device, and 1B, 2B and 58 are the three bytes to be sent to the attached device.
Vertical Tab (VT) — 0Bh
The Vertical Tab command moves the presentation position down to the next vertical tab stop position. The vertical tab stops are determined by the Set Vertical Format command. If no vertical tab stop exists below the current line, the VT is treated as a line feed.
