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Card
Load
Routine
The following five-instruction load routine is also an
example of Indirect Addressing ( special feature) .
Without Indirect Addressing, the program would re-
quire 12 instructions. The program is straightforward
and simple, and in addition simplifies the preparation
of program cards. Other advantages are:
1. Program cards may be loaded in any sequence.
2. The address being loaded is punched in card
columns 1 to 5 for easy card identification.
3. From 1 to 60 digits (as many as 5 instructions)
may be loaded by each program load card.
4. After loading data from the last program cards,
the program will branch to any address speci-
fied by the programmer in the last card and
start the main program.
5. Data cards may be placed in the card reader
with the program deck, thereby reducing card
handling.
6. Cards containing corrections to the original
program (patch cards) can be added to the
program deck whenever necessary.
7. To simplify the explanation, 19901-19980 is
used as a read-in area. It cannot be loaded by
the program. The last paragraph describes a
program that avoids this restriction.
Operating Instructions
To load the program, reset the 1620, place the card
deck in the 1622 Card Read-Punch, and press the
Load key.
Card Sequence
The cards are arranged in the following sequence:
1. The program loader card (one card, punched
with the program below).
2. Program cards (see their format below).
3. The last program card, containing the branch
address.
4. Data cards, if any.
The Program Loader Card
This card is punched in card columns 1 to 56 with
the following information:
_
_
36 19901 00500 25 00080 19910 31 19905 19920 25
19910 00080 49 19915
=1=.
It is loaded to locations
00000 to 00079 by the Load key. Note that each of
the last four instructions contains an indirect address,
referring to a field in the input area. Refer to the
PROGRAM CARD FORMAT
for an explanation of each in-
struction. The program begins at 00000, and continues:
90
Mnemonic
Location
Op Code
Instruction
Explanation
00000
RNCD
36 19901 00500 Read card to input area
00012
TD
25 00080 19910 Save digit where record
mark will fall
00024
TR
31 19905 19920 Store the instructions
from the card
00036
TD
25 19910 00080 Put the digit back again
00048
B
49 19915 =+=
Branch to 00000 or the
program
Program Card Format
19901
19910
!
~
xxxx\':
xxxxx
xxxxx
x---------x=+=
1 - 5
Address
for card
col. 20
CARD
COLUMNS
6 - 10
Address
where =+=
will fall
11 -
15
20
79 80
Blank
Program instructions or
except
constants. Last digit is
last card
followed by a =+=
EXPLANATION
1-5
The address to which the data from card
column 20 and on, will be transferred. It is
referred to indirectly in the third instruction.
No flag is needed with this or the other ad-
dresses.
6-10
The address to which the record mark will be
transferred by the third instruction. This ad-
dress is referred to indirectly to save and later
to restore the digit that will be erased by the
record mark. If the digit at that address will
be loaded by a card that follows, and if proper
program card sequence can always be main-
tained, the address may be left blank.
11-15
Blank in all but the last program load card to
cause a branch to 00000. In the last program
load card, these columns contain the address
at which the main program is to start.
16-19
Not used. Card sequence number or program
number may be punched·· here.
20-80
The data to be loaded, followed by a record
mark. The data may be any numerical data,
flagged or not. It may not contain a record
mark. The first character is in card column 20.
If one instruction is to be loaded, the record
mark should be in column 32.
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