User's Manual

XEROX LASER PRINTING SYSTEMS TAPE FORMATS MANUAL 3-1
3. 3 IBM DOS/360 GRASP tape
organization
This chapter describes the IBM DOS/360 GRASP tape organization.
It also includes a sample JSL.
Record format
Each physical record on a GRASP tape consists of two basic
elements: the identification segment and a segment containing a
variable number of logical data records (refer to figure 3-1).
Figure 3-1. GRASP physical record format
• B0 is a byte which contains the length of the ID segment in
binary.
• B1 is used as a flag byte. If bit zero of byte 1 is set to 1, then the
first logical record following the ID segment contains a line up
message-to be used for job control information by the operator.
• ID DATA, bytes 26 and 27 (zero-indexing from the start of the
block) contain the address of the phantom printer device to be
used for block selection/deletion criteria, if desired.
• F1 is a one-byte binary value which gives the length of F3. A
zero value implies end of logical records in block.
• F2 is the channel control word after resetting bit 5 to zero. In a
line-up record, the channel control word stored here is treated
as a “no operation” (NOP) by the printer.
• F3 is either a line-up message or a line of print data.