IBM 1620 1 Manual page 6

arithmetic operations without being edited for size
or position. Accuracy of results is ensured by auto-
matic validity checking which operates when the data
enters, exits, or is processed inside the system.
The operator's console includes control keys,
switches, indicators, and an input/output typewriter.
The control keys and switches are used for manual
and/or automatic operation of the system. The indi-
cators provide visual indication of the status of various
registers, program indicators, and input/output units.
The typewriter enables operator entry of data and
instructions into core storage; it also provides a per-
manent log of operator intervention during program
operation. As an output unit, the typewriter provides
operator-oriented messages of job progress and detail.
Information is entered into the system via the
following input units: 1621 Paper Tape Unit, 1622
Card Read-Punch, 1311 Disk Storage Drive, and the
console typewriter. Maximum input speeds are:
1621-150 characters per second
1622 Model 1-250 cards per minute
1622 Model 2-500 cards per minute
1311-100 characters (one sector of data) per 2
ms. Seek time (the time required to move
the read/write heads to the desired disk
track) is 75 ms minimum, 250 ms average,
and 392 ms maximum. This time is zero if the
heads are already located at the proper
disk track.
Console typewriter-operator's speed
The system provides output information via the
1622, the tape punch in the 1621, the console type-
writer, the 1443 Printer, and the 1627 Plotter. (The
1621 and 1627 units cannot be installed on the same
2
system except by special order.) Maximum output
speeds are:
1443 Model 1-430 lines per minute
1443 Model 2-600 lines per minute
1621-15 characters per second
1622 Model 1-125 cards per minute
1622 Model 2-250 cards per minute
1627 Model 1-18,000 steps per minute (11 inch
horizontal plot)
1627 Model 2-12,000 steps per minute
(2m~
inch
horizontal plot)
Console typewriter-10 characters per second
The 1443 and 1622 units contain buffer storage
media, which enables
CPU
operation concurrent with
printing, card reading, and card punching. When
printing and/or punching, the
CPU
transfers the out-
put data from core storage to the 1443 print buffer
and the 1622 punch buffer in 8.06 ms and 3.4 ms,
respectively, and then continues program operation
while the line is being printed and the card is being
punched. Simultaneously, the data from a card in the
1622 read feed can be read into the read buffer.
Following loading of the read buffer, the
CPU
transfers
the card data to core storage and then continues proc-
essing while the next card is being read into the read
buffer. Thus, reading, punching, and printing can
be done simultaneously.
Detailed information concerning 1620 input/output
units and special features is available in the
IBM
publications referred to on the cover page of this
manual.