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Examples of a paper tape load routine and a card load
routine are explained in detail in this section to il-
lustrate the concept of program loading.
Paper Tape Load Routine
Large records, like small records, consist of data (pro-
gram instructions are also considered data) and an
EL
punch in paper tape. The
EL
punch, which termi-
nates the record, enters core storage as a record
mark
(=1==).
The format below represents a large rec-
ord in core storage.
DATA.
. . . . . . .
=1==
The following format represents the same record
separated into four smaller records by
EL
punches
in the paper tape.
DATA ..
~
DATA ..
~
DATA ..
~
DATA ..
~
Each
EL
punch causes a record mark to replace a
character in core storage. Where individual records
are interspersed in core storage, rather than stored in
continuous line, it is sometimes necesary to restore
the characters that the record marks replace. This is
done by transferring each character to another loca-
tion before the record mark replaces it, and then, after
the record mark has been stored, to transfer the char-
acter back, wiping out the record mark. The following
load routine saves these characters. Read the explana-
tion completely for clarification of early steps.
The format of the load routine and of data records
in paper tape is:
LOAD ~ ddddd 1 36aaaaal ~ DATAl .. ~
ddddd 2 36aaaaa2 ~ DAT A 2 . . ~. The load routine
is represented by LOAD. Each ddddd36aaaaa is an
addressing record for the next data record (DATA ..
~
). ddddd is the address of the character that will
be replaced by the following DATA record mark, and
aaaaa is the address that the following DATA record
will be read into. The LOAD and addressing record
marks are of no concern.
The load routine (LOAD) is read in by use of the
Insert (36 00000 00100), Release, and Start keys. The
load routine is as follows:
00000 41 00000 00000
00012 36 00031 00300
NoOp
Read paper tape into
00031
00024 25 00071 ddddd Transfer digit from
location ddddd to 00071
Appendix G - Program Load Routines
00036 36 aaaaa 00300
Read paper tape into
aaaaa
00048 26 00066 00035
Transfer field from
00035 to 00066
00060 15 00000 00000
Transfer Digit Imme-
diate
00072 49 00012
Branch
After the load routine reads from paper tape into
core storage locations 00000-00079 as a result of the
above Insert operation; Release and Start key depres-
sions are again required to initiate computer opera-
tion at 00012. The second Load instruction is execut-
ed, and the first addressing record, ddddd136aaaaal
~ ~
replaces part of the third and fourth Load in-
structions. The placement of the
~
in Q7 of the fourth
instruction is of no concern.
ddddd is the predetermined location of the char-
acter in core storage that the next DATA record mark
temporari1y replaces. The character is saved (third
instruction) and transferred back (sixth instruction)
to replace the
~.
aaaaa is the core storage location for each DATA
record.
The third instruction, now 25 00071 ddddd, is ex-
ecuted. The character at ddddd is transferred to 00071
(Ql1 of the sixth instruction).
The fourth instruction, now 36 aaaaa 00300, is ex-
ecuted. The next DATA record enters core storage,
beginning at location aaaaa.
The fifth instruction, 26 00066 00035, is executed,
and ddddd becomes the P address of the sixth in-
struction.
The sixth instruction, now 15 ddddd OOOOX (X is
the saved character) transfers the saved character
back to its original location. Thus, the
~
at the end
of each data record is replaced by the character that
was there to begin with.
The last instruction of the load routine, 49 00012,
branches the computer to the second instruction, and
reads in the addressing record for the next data
record.
The last addressing and data records are used to
branch the computer to the starting address of the
loaded program. They are 00079360007 4 ~ and sssss
~
(sssss is the starting address).
89
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