User's Manual

XEROX LASER PRINTING SYSTEMS TAPE FORMATS MANUAL 15-1
15. 15DEC PDP-11 tapes
This chapter describes tape and file formats for the DEC PDP-11
system. It also includes a JSL sample.
Tape formats
The Xerox printing system accepts tapes produced on DEC PDP-11
computers by the FLX utility. These tapes are often defined as the
DOS format available on the PDP-11 computer operating systems.
File formats
Each file on a magnetic tape is followed by a single tape mark, and
two tape marks end the tape. A tape mark encountered in
conjunction with an end-of-tape reflector indicates an end-of-volume
condition. (Refer to figure 15-1.)
Each tape file begins with a tape label record, followed by any
number of data records (generally 512 bytes per record) and ends
with a tape mark. These files may contain zero data records.
The label record is 14 bytes long. The format of the label is shown in
table 15-1. The Xerox/OSS uses the protection code of X‘9B’ or
O‘233’ to verify a DEC PDP-11 label. A BDELETE is used to delete
the label block (see the printing system reference manual for block
deletion).
Table 15-1. FLX label
Field
Character
posistion(s
)
Name Length Description
1 1-4 File name 4 2 words stored in RADIX 50 format
2 5-6 File type 2 1 word in RADIX 50
3 7-8 Programmer and project
number
2 —
4 9 Protection code 1 X’9B’ or 0’233’
510 Unused 1—
6 11-12 Creation date 2 Internal date format
7 13-14 Unused 2 —