6530 Programmer's Guide

Block Mode Operation
3-42
6530 Programmer’s Guide
In protect submode, the text transmitted consists of data stored in
unprotected fields (and, in some cases, protected fields if their MDTs are
set). The content of each field is preceded by a DC1 sequence that
specifies the address for that field. This address is the address of the first
unprotected position in the respective field; thus, it is the address of the
video attribute for that field plus one. Trailing spaces in a field are not
transmitted. If a field contains only spaces, only the field separator (DC1
plus the 2-character address) is transmitted. Esc 6 sequences are handled
the same way as in nonprotect submode. The following example shows
the general format of transmitted data:
With some of the escape sequences, you can select a portion of the page
to be read. In these cases, the transmission begins at the specified read
start address and continues through a specified read end address on the
selected page.
In protect submode, the transmission starts with the first field that begins
at or after the read start address. (The beginning of the field is the first
position after the video attribute for that field.) Thus, if the specified read
start address is not at the beginning of a field, the transmission starts at
the next field. The transmission stops at the first end of field that is equal
to or greater than the read end address. (The end of a field is the last
position in that field, before the video attribute of the next field.) Thus, if
the specified read end address is within a field, the transmission
continues past this address to the end of the field and stops.
The following examples illustrate some of the various cases that you may
encounter. (The examples assume that the MDTs are set in all fields
shown.)
DC1 address (address of first unprotected field)
displayable data (text for first unprotected field)
.
.
.
DC1
address (address of next unprotected field)
displayable data (text for next unprotected field)
.
.
.
etc.