RCA 301 User manual

RCA
ELECTRONIC
3 0 1
L. Morr/s CSCP
LLMorris CSCW
DATA PROCESSING SYSTEM
PROGRAMMERS'
REFERENCE
MANUAL
RADIO CORPORATION OF AMERICA
Electronic Data
Processing,
RCA-Cherry
Hill
Camden 8, N. J.
93-16-000
November, 1966

The information contained herein is subject
to change without notice. Revisions ifiay be
issued to advise of such changes and/or
additions.
Reissued: June, 1964
This manual has been reprinted to include
all revisions through November, 1966.

L. Morris
CONTENTS
Page
I —THE RCA 301 SYSTEM — GENERAL DESCRIPTION
Introduction 1-1
System Elements Description 1-1
The RCA 301 Code 1-5
Organization of Data 1-7
II —PERIPHERAL EQUIPMENT — FUNCTIONAL DESCRIPTION
Card Equipment II-1
Paper Tape Equipment II-2
On-Line Printer II-3
Monitor Printer II-4
Interrogating Typewriter II-4
MICR Sorter/Reader II-5
Hi-Data Tape Group, Model 381 II-5
Hi-Data Tape Group, Model 382 II-6
33KC Magnetic Tape Station II-6
66KC Magnetic Tape Station II-6
Multiple Tape Lister II-7
'Data Exchange Control II-7
Random Access Computer Equipment II-7
Data Record File H-7
Data Disc File H-8
3488 Unit jj.g
III — THE COMPUTER — FUNCTIONAL DESCRIPTION
High Speed Memory III-l
The Basic Instruction III-l
Program Control HI_3
The Console 111-10
IV — THE RCA 301 INSTRUCTIONS — GENERAL DESCRIPTION IV-1
V — DATA HANDLING INSTRUCTIONS
Translate by Table (A) y_3
/ Locate Symbol Left (K) V-5
Locate Symbol Right (L) y_7
^ Transfer Data Left (M) y_9
• Transfer Data Right (N) V-10
v Transfer Data by Symbol Left (#) V-ll
y Transfer Data by Symbol Right (P) V-12
Transfer Symbol to Fill (J) V-13
VI — ARITHMETIC INSTRUCTIONS
Add ( + ) VI.3
Subtract ( —) Vl.g
Logical "OR" (Q) yj.g
Logical "AND" (T) VI-10
Exclusive "OR" (U) VI-12
VII — DECISION AND CONTROL INSTRUCTIONS
Store Register (V) VII-3
• Conditional Transfer of Control (W) VII-5
•Compare Left (Y) VII-7
iii

VII — DECISION AND CONTROL INSTRUCTIONS (Cont'd) Page
Tally (X) VII-9
^ Halt (.) VII-10
• Repeat (R) VII-11
VIII — INPUT/OUTPUT INSTRUCTIONS — CARD
Card Read Normal (0) (Model 323 Card Reader) VIII-3
Card Read Normal (0) (Model 324, 329 Card Reader) VIII-5
w- Card Read Normal (0) (Model 330 Card Reader-Punch) VIII-7
Card Read Simultaneous (1) (Model 323 Card Reader) VIII-9
Card Read Simultaneous (1) (Model 324, 329 Card Reader) VIII-11
Card Read Simultaneous (1) (Model 330 Card Reader-Punch) VIII-12
Card Punch Normal (2) (Model 334 Card Punch) VIII-14
Card Punch Normal (2) (Model 336 Card Punch) VIII-15
\SCard Punch Normal (2) (Model 330 Card Reader-Punch) VIII-16
Card Punch Simultaneous (3) (Model 334 Card Punch) VIII-17
Card Punch Simultaneous (3) (Model 336 Card Punch) VIII-18
Card Punch Simultaneous (3) (Model 330 Card Reader-Punch) VIII-19
^"Input/Output Control (;) (Model 330 Card Reader-Punch and Model 324, 329 Card Reader) . . VIII-20
v"Input/Output Sense (S) VIII-21
IX — INPUT/OUTPUT INSTRUCTIONS — TAPE
/Tape Read Forward Normal (4) IX-3
Tape Read Forward Simultaneous (5) IX-6
vTape Read Reverse Normal (6) IX-7
Tape Read Reverse Simultaneous (7) IX-9
•/Tape Write Normal (8) IX-10
Tape Write Simultaneous (9) IX-12
v R ewind to BTC (;) IX-13
/Input/Output Sense (S) IX-14
/Automatic Rollback Control (S) IX-16
/Sense Read Error (S) IX-17
X — INPUT/OUTPUT INSTRUCTIONS — PRINTER
" Print and Paper Advance Normal (B) X-3
Print and Paper Advance Simultaneous (C) X-5
/Input/Output Sense (S) X-7
XI — INPUT/OUTPUT INSTRUCTIONS — DATA RECORD FILE
Band Select Normal (D) XI-3
Band Select Record File Mode (E) XI-5
Block Read Record Normal (F) XI-7
Block Read Record Simultaneous (G) XI-9
Block Write Record Normal (H) XI-11
Block Write Record Simultaneous (I) XI-13
Record File Mode Read (*) XI-15
Record File Mode Write (%) XI-17
Input/Output Sense (S) XI-19
XII — INPUT/OUTPUT INSTRUCTIONS — DATA DISC FILE
v/ Track Select (D)
v'Sector Read Disc Normal (F)
Sector Read Disc Simultaneous (G)
v
Sector Write Disc Normal (H)
XII-3
XII-4
XII-6
XII-8
iv

L .i Morris
XII — INPUT/OUTPUT INSTRUCTIONS —DATA DISC FILE (Cont'd)
Page
Sector Write Disc Simultaneous (I) xn jq
-'Input/Output Sense (S) XII-12
XIII — INPUT/OUTPUT INSTRUCTIONS —DATA EXCHANGE CONTROL
- Tape Read Forward Normal (4) XIII-3
• Tape Read Forward Simultaneous (5) XIII-4
^ Tape Write Normal (8) xm ^
Tape Write Simultaneous (8) XIII-6
• Input/Output Sense (S) xm
7
XIV —INPUT/OUTPUT INSTRUCTIONS — MULTIPLE TAPE LISTER
Print Tape Normal (8) xjy ^
Print Tape Simultaneous (9) xjy
4
Input/Output Sense (S) XIV-5
XV — INPUT/OUTPUT INSTRUCTIONS — RANDOM-ACCESS COMPUTER EQUIPMENT
SeIect
(°) XV-3
Read Normal (4)
Xy 5
Read Simultaneous (5) ,
Write Normal (8)
Xy
^
Write Simultaneous (9) xy
g
Input/Output Sense (S)
xv
APPENDICES
A — RCA 301 Codes ^
B — List of Instructions g
}
C — Summary of Instructions ^
1
D — Instruction Timing
E Standard High Speed Memory Locations £ ^
F-I — Symbols Used for N Character Counts Except in Repeat and Paper Advance F-l
F-II — Symbols Used for N Character Counts in Repeat and Paper Advance Instructions F-l
G — Device Identification for Input/Output and IOS Instructions r i
H — Print Table
H-1
I — Control Characters and Printable Characters for the Multiple Tape Lister '
M
J — Glossary of Terms
ILLUSTRATIONS
Figure
1. Recording on Data Disc File j
g
2. Recording on Magnetic Record j
g
3. Recording on Hi-Data Tape j
4. Recording on Paper Tape
I g
5. Block Diagram of Basic RCA 301 Computer
m 4
6. RCA 301 Console Display
111-13
v

HRSfOTPflf
I
I
I
•
I

THE RCA 301 S YSTEM
L.r Morris
I — GENERAL DESCRIPTION
INTRODUCTION
The RCA 301 Electronic Data Processing System is a general purpose, stored program, digital processor employing
solid-state electronic circuitry. Highly flexible RCA 301 Systems are integrated from a diversified array of input/
output devices, a range of memory sizes, and other special features. Each System is tailored to meet the data
processing requirements of a specific organization. While each RCA 301 System is complete within itself, a high
degree of compatibility has been attained with the medium-scale RCA 501, the medium-scale RCA Realcom 3301,
and the large-scale RCA 601.
System efficiency is enhanced by:
• Rapid memory access time
• Character addressability providing completely variable data organization
• Decimally addressed memory
• Built-in and programmed accuracy controls
• Machine code covering full range of numerics, alphabetics, and special symbols
• Automatic and programmed storage in High-Speed Memory of the contents of various Program Control
Registers
• Direct and Indirect Addressing
• A powerful programming instruction repertoire including the following:
• A Translate by Table instruction permitting efficient internal processing of various code structures
• Locate Symbol instructions permitting an internal search within High-Speed Memory for any character
designated
• Transfer instructions permitting transfer of data to left or right within High-Speed Memory
• Arithmetic instructions permitting Logical "OR", Logical "AND" and Exclusive "OR"
• A Repeat instruction permitting the next repeatable instruction to be repeated a specified number of times
• Automatic programming aids include RCA 301 COBOL, Assembly System, FORTRAN, and a Scientific
Interpreter. An extensive library of service and maintenance routines is also available.
The System processes information prepared by a variety of input media for distribution to the appropriate out-
put. The complete compatibility of System elements provides for ease of expansion at a later date, which is part
of the System philosophy.
SYSTEM ELEMENTS DESCRIPTION
The RCA 301 Computer comprises a Processor and appropriate Input/Output Control Modules. The latter
operate the peripheral devices connected in the system. The Processor is a general purpose, stored program, digital
machine which includes the following sub-units: High-Speed Memory, Program Control, Console Panel, and Power
Supply. The Simultaneous Mode Control may be included in the system to provide concurrent operation of two
input/output devices, or an input/output instruction with a compute instruction.
The High-Speed Memory is a random access, magnetic core device which provides storage and work area for
programs and data. The memory capacity is 10,000 (Model 303), 20,000 (Models 304 and 354), or 40,000 (Models
305 and 355) alphanumeric characters. Each location is decimally addressable and can store one of the RCA 301
characters. The RCA 301 code includes all the letters of the alphabet, the ten decimal digits, and control and special
symbols. (Refer to 301 Code Chart, Appendix A.) The memory cycle time to address, bring into register, and regenerate
a diad in its original memory location is 7 microseconds.
1-1

The Program Control executes the instructions of the program stored in the High-Speed Memory and performs
the automatic accuracy checks. The classes of instructions are: Data Handling, Arithmetic, Decision and Control,
and Input/Output. Both direct and indirect addressing can be employed.
The Console Panel provides for complete monitoring of operation of the Processor. Adequate indicators and
controls are provided on the panel to initiate normal computer operation and to facilitate program check-out and
maintenance.
The Power Supply distributes power to the Processor and to certain Peripheral Equipments which require d-c
or regulated a-c power. Other Peripheral Equipments, not requiring d-c or regulated a-c, are supplied from the power
mains individually.
The Simultaneous Mode Control pemits the operation of one input/output device simultaneously with another
operation being performed by the Computer. This other operation being performed by the Computer can be a second
input/output instruction or a compute instruction.
The Record File Mode Control provides an additional degree of simultaneity so that reading from or writing to
one of four Data Record Files can be time-shared with other operations.
The Input/Output Control Modules control the peripheral equipment, generally one for each device used in a
system. The modules are installed only when their associated input/output devices, described in succeeding para-
graphs of this section, are added to the system.
The Card Reader, Model 323, reads information punched in 80-column cards for transfer to the Processor.
Hollerith card code may be automatically translated to RCA 301 code. It is possible to bypass automatic translation
and read cards binarily. Cards are read at rates up to 600 cards per minute. Information may be edited and rearranged
under program control.
The Card Reader, Model 324, reads information punched in 80-column cards for transfer to the Processor.
Automatic translation between Hollerith card code and 301 code is provided under program control. Cards may be
read binarily under program control. Reading is performed at a rate of up to 900 cards per minute.
The Card Reader, Model 329, reads information punched in 80-column cards for transfer to the Processor.
Automatic translation between Hollerith card code and 301 code is provided under program control. Cards may be
read binarily under program control. Reading is performed at a rate of up to 1500 cards per minute.
The Card-Reader-Punch, Model 330, consists of an 80-column card reader and card punch in the same
enclosure. Reading is performed at rates up to 800 cards per minute and punching at rates up to 250 cards per
minute. Automatic translation between Hollerith card code and 301 code is provided. Under program control, auto-
matic translation may be by-passed to permit reading or punching binary coded cards. Card reading, punching and
editing are performed under complete control of the stored program. Concurrent reading and punching may be
performed when the Simultaneous Mode Control is included in the system.
Paper tape input and output is provided by three optional paper tape devices. The Paper Tape Reader and
Punch, Model 321, is a single unit which permits on-line reading from and punching either 5 or 7-channel paper
tape at the rate of 100 characters per second. The Paper Tape Reader, Model 322, is a single unit which permits
on-line reading from 5, 6, or 7-channel, odd or even parity, paper tape at either 500 or 1000 characters per second.
The Paper Tape Punch, Model 331, is a single unit which permits punching 5 or 7-channel paper tape at 100
characters per second.
The High-Speed Paper Tape Punch, Model 332, is a single unit which permits punching of 7-channel paper
tape at 300 characters per second.
Two models of the On-Line Unbuffered Printer are available; one printing 120 characters per line (Model 333)
and the other printing 160 characters per line (Model 335). The 120-characters per line model has a printing rate
up to approximately 1000 lines per minute during synchronous printing, with the ability to print 47 selected
characters, and up to approximately 800 lines per minute, with the ability to print 64 characters. The 160-character
per line model has a printing rate up to approximately 1075 lines per minute, with the ability to print from 47 selected
characters, and up to approximately 835 lines per minute, with the ability to print 64 characters. Two 120-character
1-2

or two 160-character printers can be operated simultaneously in the system. Paper can be advanced at the rate of
150 lines a second on both models, independently of normal data processing activity. The printer operation, variations
in format, and complete editing are under the control of the stored program.
Two models of the On-Line Buffered Printer are available, one printing 120 characters per line and the other
printing 160 characters per line. Buffer storage capacity of the 120-character per line model is 184 characters (120-
character data line plus 64-character print table); buffer storage capacity of the 160-character per line model is
224 characters (160-character data line plus 64-character table). Scanning references the data line and the print
table in the buffer. The Processor mode is free on completion of transfer to the buffer. Data transfer is by diad,
at the rate of 14 microseconds per diad. Printing and paper advance are accomplished off-line. Rated speeds for
printing and paper advance are the same as specified for the unbuffered models.
The Monitor Printer, Model 338, is used for listing intermediate or final totals of a computer program,
summary reports or for program testing. The output rate is up to 10 characters per second. All of the 301 characters
may be printed.
The Interrogating Typewriter, Model 328, is an input/output device, which allows inquiry messages to be
entered into the system via a keyboard, and data from the computer to be printed at a rate of up to 10 characters per
second. All of the 301 characters are used. The operation is performed under control of the stored program.
The MICR Sorter/Reader sorts magnetically encoded documents under control of the stored program. Data is
also verified and accumulated for further processing by the Computer. Six-inch documents can be read at rates up
to 1560 per minute. A supplementary programmers' reference manual (#93-16-001) is available for use in program-
ming this equipment.
The Data Record File, Model 361, provides mass storage of over 4.6 million characters per file. Each file
contains 128 magnetic records. From one to 9000 characters may be transferred between High-Speed Memory and
the Data Record File, with one instruction, at a transfer rate of 2500 characters per second. As many as six Data
Record Files can be used in the system with as many as three of the files being written to or read from simultaneously.
A"
The Data Disc File, Model 363, provides rapid random access storage in modules of 22 million alphanumeric
characters. Each side of a magnetic disc is divided into 1152 data tracks. The contents of a complete track (1600
characters) can be transferred between High-Speed Memory and the Data Disc File, with one instruction, at a transfer
rate of 32,000 characters per second.
The Hi-Data Tape Group, Model 381, is composed of a cluster of up to six tape decks with a common set of
controls, power supply, and switching circuits. Reading is performed in either the forward or reverse direction.
The read/write rate is approximately 10,000 alphanumeric characters per second. Two Hi-Data Tape Groups may
be utilized in a system for a total of 12 tape decks. In this case, two tape decks, one from each group, may be
operating simultaneously.
The Hi-Data Tape Group, Model 382, is composed of a cluster of up to six tape decks with a common set of
controls, power supply and switching circuits. Reading is performed in either the forward or reverse direction. The
read/write rate is approximately 30,000 alphanumeric characters per second in the 382 Mode and 20,000 alpha-
numeric characters per second in the 381 Mode. Two Hi-Data Tape Groups, Model 382, may be utilized in a system
for a total of 12 tape decks. In this case, two tape decks, one from each group, may be operating simultaneously.
With a special control module and special features on each tape deck, two tape decks in the same group may be
operating simultaneously.
33KC Magnetic Tape Stations are operated through either 33KC Tape Adapters or 33KC Dual Tape Channels.
Reading is performed in either the forward or reverse direction. The read/write rate is approximately 33,333 alpha-
numeric characters per second. Up to 14 33KC Tape Stations may be operated in the system.
66KC Magnetic Tape Stations are operated through either 66KC Tape Adapters or 66KC Dual Tape Channels.
Reading is performed in either the forward or reverse direction. The read/write rate is approximately 66,667 alpha-
numeric characters per second. Up to 14 66KC Tape Stations may be operated in the system.
The Multiple Tape Lister, Model 340, is an electro-mechanical printer available in two models. The first model
has 6 separate paper feed units and the second has 12 separate paper feed units. The maximum printing rate is
2,000 lines per minute. Printing can take place on any one listing tape or a maximum of two listing tapes simultaneously.
1-3

The Data Exchange Control, Model 377, enables any two 30i Processors, each equipped with this control
to communicate with each other. A second Data Exchange Control may be attached to a 301 Processor when it is
necessary for this Processor to communicate with two other 301 Processors. Data may be transmitted in either
direction but in only one direction at a time. The transfer rate is dependent upon the mode in which the transfer
is made and the availability of status levels in both Processors.
Communications equipment may be included in a system via the Communications Mode Control, Model 378.
A supplementary programmers' reference manual (#93-16-006) is available for use in programming this equipment.
The Videoscan Document Reader, Model 5820, is a high-speed numeric optical character reader which will
read documents of various sizes containing numeric data and/or four special symbols. The data is translated auto-
matically for input to the Processor. The reading rate is either 750 documents per minute or 1500 documents per
minute as determined by a manual switch setting. A supplementary programmers' reference manual (#93-16-004)
is available for use in programming this equipment.
Two additional 301 Processor models are available. The memory capacity is 20,000 (Model 354) or 40,000
(Model 355) alphanumeric characters. In addition to the standard 301 System programming instructions, the
enhanced logic of these processors provide high speed fixed point or floating point arithmetics with associated auto-
matic address modification capabilities. A supplementary programmers' reference manual (#93-16-003) is available
for use in programming this equipment.
Accuracy Control
Adequate accuracy checking techniques are used in the System to assure correct data processing. Correct parity
is ascertained on read-in, during data flow in the Computer, and on write-outs. If a parity error occurs in one of
the Computer modes (Normal, Simultaneous or Data Record File) the mode in which the error occurs is stopped
immediately. The other modes complete their function.
Accuracy of information from the Card Reader and to the Card Punch is assured by use of two separate reading
stations in the Card Reader, and a reading station following the punch unit in the Card Punch. When reading cards
in the Translate Mode of operation, any non-RCA 301 Card Code combination (excluding Y/0) is detected, trans-
ferred into memory as an octal 57 (578), and both the Computer and Card Reader halt after the complete card image
has been transferred to m
A parity check is made of paper tape characters (odd or even input parity) when transferred to the Computer,
and an echo check is made of those characters punched onto paper tape.
With the unbuffered printer, a read error condition (RE) is indicated when the printer table character stored
in the control module for scanning the print field has a parity error. With the buffered printer, RE is indicated for
a parity error on transfer into the buffer.
With the unbuffered printer, a write error condition (WE) is indicated when either of the characters in the diad
sent to the Printer Control module for comparison has a parity error. With the buffered printer, WE indicates
detection of an off-line (printer accessing buffer) parity error. WE indication occurs on the next command to the
printer.
A DDF occurs if the device is inoperable or a line advance or a page change command is received when a low
paper supply exists.
The Data Record File possesses a lock-out feature to prevent writing on a "master" record. An accuracy check
also warns of malfunctioning Block or Character Counter.
The Data Disc File checks if the positioner is in the correct track, and it has a bit counter to assure that the
bit-serial to character-serial conversion is functioning properly. If a character with faulty parity is read, an octal
57 (57g) will be stored in memory in place of the faulty character and an indicator will be set which can be sensed
at the termination of the read instruction.
Magnetic Tape accuracy features include end of reel stops, both beginning of tape and end of tape warning,
dual recording, write lockouts, correct parity of data read and read after write accuracy check.
A parity check is performed on data received from the Interrogating Typewriter. When operated as an output
device, an echo check for correct parity is performed between the typewriter and the control module.
1-4

Application of Accuracy Checking Techniques
Program Control—The following controls are typical of conditions causing the computer to stop:
1. Incorrect parity in Memory Address Register.
2. Incorrect parity in Memory Register.
3. Incorrect parity in Operation Register.
4. Incorrect parity in N Register.
5. Incorrect parity in Repeat (NR) Register.
Input I Output—The following are input/output conditions which may cause the Computer to stop:
1. Incorrect parity of data being transferred.
2. Input/Output device inoperable or not following command.
3. Record not on turntable of Data Record File.
4. Attempting to write to record or magnetic tape when lockout device applied.
5. Card equipment input hopper empty or output hopper full.
6. Non-RCA 301 card character read by the Card Reader, when in the Translate Mode.
7. Tape Station reading extra bits in interblock gap.
8. On-Line Printer paper supply low.
THE RCA 301 CODE
The RCA 301 System employs a binary code using seven binary digits, or bits to represent each RCA 301
character. Of the seven bits which make up each of the characters, the highest order bit (26) is the parity bit. The
remaining six bits are the information bits, with a specific configuration of bits representing each RCA 301 character.
Bit Position
P
2s
2" 23 2J
V
2°
Bits
X X X
X X
X X
(X = 0 or 1)
For ease in presentation, the bit configurations of the RCA 301 Code are divided into four groups with the
zone bits (25 and 24) designating the group, as follows:
RCA 301 GROUP CODE
25
24
23
22 2'
2°
Group 1
0 0 X X X
X
Group II
0
1
X X
X
X
Group III
1
0 X X
X
X
Group IV
1 1 X X
X
X
1-5

The following table shows the bit configuration for each RCA 301 character. The parity bit (26) is not shown
in this table but is inserted in each configuration to indicate an odd parity count.
RCA 301 CODE
Group 1
Group II
Group III
Group IV
2s 24
25 24
2S 24
3?
24
23
2J 2'
2°
0 0
•-1 (V
0 1
1 0
1 1
2-
/
0
&
— ( minus)
ft
0
0 0 0
1
A
J
/
0
0 0
1
2
B
K
S
0 0
1
0
3
C
L
T
0 0
1
1
4
D
M
U
0
1
0
0
5
E
N
V
0
1
0
1
6
F
O
w
0
1
1
0
7
G
P
X
0
1
1
1
8
H
Q Y
1
0 0
0
9
I
R
Z
1
0 0
1
(space)
+
EI
EB
1
0 1
0
#
. (period)
$
, (comma)
1
0
1 1
@
9
*
%
1 1
0
0
(
:
ED
• (ISS)
1
1
0
1
)
(apostrophe)
EF
=
1
1
1
0
On 80 column cards, the groups are designated by the presence or absence of zone punches. Group I has no
zone punch. Group II has a Y zone punch, Group III has an X zone punch, and Group IV has a 0 zone punch.
RCA 301 programs are written using alphanumeric characters. Memory Locations are addressed as follows:
Memory Locations
Addresses
Memory Locations
Addresses
0000 to 9999
0000 to 9999
24000 to 24999
M000 to M999
10000 to 10999
&000 to &999
25000 to 25999
NOOO to N999
11000 to 11999
A000 to A999
26000 to 26999
O000 to 0999
12000 to 12999
B000 to B999
27000 to 27999
P000 to P999
13000 to 13999
C000 to C999
28000 to 28999
Q000 to Q999
14000 to 14999
DOOO to D999
29000 to 29999
R000 to R999
15000 to 15999
E000 to E999
30000 to 30999
"000 to "999
16000 to 16999
FOOO to F999
31000 to 31999
/000 to /999
17000 to 17999
GOOO to G999
32000 to 32999
S000 to S999
18000 to 18999
H000 to H999
33000 to 33999
T000 to T999
19000 to 19999
1000 to 1999
34000 to 34999
U000 to U999
20000 to 20999
— 000 to —999
35000 to 35999
V000 to V999
(minus) (minus)
36000 to 36999
W000 to W999
21000 to 21999
J000 to J999
37000 to 37999
XOOO to X999
22000 to 22999
K000 to K999
38000 to 38999
Y000 to Y999
23000 to 23999
LOOO to L999
39000 to 39999
Z000 to Z999
1-6

ORGANIZATION OF DATA
Definitions
Bit: A bit is a single binary digit, having a value of either zero or one.
Character: An RCA 301 character consists of six information bits and one parity bit combined to represent a
decimal digit, a letter of the alphabet, a punctuation or other special mark, or a control symbol.
Item: An item consists of such characters as are necessary to specify a particular unit of information (a numerical
quantity, an alphabetic name, a street address, a stock number, etc.). In many cases an item is preceded by a symbol
to define the beginning of each item.
Record: A record consists of one or more related items with the amount of information in a record being
completely variable.
Line: A line is composed of the characters that are to be printed on a single line on the On-Line Printer. One
model of the On-Line Printer permits 120 characters to be printed per line. A second model permits 160 characters
to be printed per line.
Block: On magnetic and paper tape a block is a group of at least three characters preceded and followed by a
blank space called an "interlock gap."
On the Data Record File record a block is defined as the information contained in one cell. From one through
900 characters of information may be recorded in a cell. If the block is composed of less than 900 characters, the
last character will be an EB symbol (End of Block). If the block is composed of 900 characters, the last character
may or may not be an EB symbol. On the Data Disc File disc a block is defined as the information contained in
1 to 10 sectors. Each sector contains 160 characters.
File: A file consists of any number of related information records and may consist of only a part of a Data
Record File record or Data Disc File disc, or several records or discs. On magnetic tape it may consist of several
tapes or any part of one tape.
Organization of Data on Paper Tape
In the RCA 301 system, characters are represented on paper tape by combinations of holes punched in rows
across the tape. A hole represents a zero bit in F1SM; the absence of a hole represents a one bit in HSM (see Figure 4).
Organization of Data on a Data Record File Record
Bits are recorded as magnetic spots on the face of each Data Record File record. Characters are written and
read out in bit-serial fashion, the seven bits of each character following each other in a spiral around the disc, as
shown in Figure 2.
Each side of the record is divided into two bands; each band is composed of ten cells; each cell has the capacity
to store 900 characters. The cells on a record are addressable individually or in groups of consecutive cells up to a
total of 10.
Organization of Data on a Data Disc File Disc
Bits are recorded as magnetic spots on the face of each Data Disc File disc. Characters are written and read
out in bit-serial fashion. The seven bits of each character following each other in concentric tracks around the
discs as shown in Figure 1.
Each side cc the disc is divided into nine zones of 128 tracks each. Each track contains 10 sectors of 160
characters each, The sectors are addressable individually or in groups of consecutive sectors up to a total of 10.
Organization of Data on Magnetic Tape
In an RCA 301 system, characters are recorded on magnetic tape as magnetic spots in rows across the tape.
On Hi-Data Tape, a magnetized spot represents a zero bit; the absence of a spot represents a one bit. All characters
1-7

Figure 3—Recording on Hi-Data Tape
Model 381
128 INTERLACED DATA
TRACKS IN EACH
o-8
Figure 1
—Recording on the Data Disc
READ-WRITE
HEAOS
128 SINGLE DATA
TRACKS IN EACH
p
25 24
23 22 2
1
2
c
0
o
o
O O
o
o
O oO
o
o
o
O O
o
o o
o
o
O
o
o
o o
O O
o
o
o o
O oO
o
Figure 4—Recording on Paper Tape
Figure 2—Recording on the Data Record
1-8

are recorded on tape serially so that the characters making up an item follow one another in sequence from most to
least significant. Interblock gaps on the Hi-Data Tape Group, Model 381, are nominally .34 inch. Interblock gaps
on the Hi-Data Tape Group, Model 382, are nominally .54 inch. All data on 33KC and 66KCTrtiagnetic tape is dually
recorded. Interblock gaps on 33KC and 66KC tape are nominally .45 inch and .55 inch respectively.
Variable Item and Record Length
Data storage in the RCA 301 system incorporates true variable item length. This concept may be more fully
appreciated if prefaced with a definition of fixed and fixed variable word and block lengths.
"Word" is generally defined as a fixed number of consecutive characters or character locations, and "block"
as a fixed number of consecutive words. These terms, word and block, are more aptly used with respect to fixed
and fixed variable systems.
In a computer system using fixed word length, the number of characters for each word, or the number of words
for each block, cannot be changed. In order to store data of a varying nature, redundant zeros or spaces are used to
fill out the incomplete words, with uneconomical use of space.
In a fixed variable system, the number of character positions for each item in a record is assigned in accordance
with the anticipated maximum length for that .item. These lengths may be individually predetermined for each file,
but remain constant for each item within the file. Fixed variable word length does provide greater flexibility than
does fixed word length.
Data storage in a true variable length system does not have the limitations imposed by fixed or fixed variable
systems. In the RCA 301, the use of control symbols and the ability to address each character location individually
permits the length of any item in any record to be in strict accordance with that item's actual character count. This
allows for total variability of item and record length but does not preclude the use of fixed or fixed variable lengths
when the programmer finds this expedient.
In each of these categories—fixed, fixed variable, and variable, the method of internal storage is extended to
the external storage. Therefore, if redundant zeros of the fixed and fixed variable systems are used in the computer,
they would also appear on magnetic tape or other storage devices. By utilization of true variable length in the RCA 301
system, a characteristic business file requires less space in the Data Disc and Data Record File and less tape footage,
and can be read and written out in less time than a fixed or fixed variable system would permit.
1-9

PERIPHERAL EQUIPMENT
|| — FUNCTIONAL DESCRIPTION
CARD EQUIPMENT
The punched card equipment includes the Card Reader, Models 323, 324, and 329, two models of Card Punches
and the Card Reader-Punch.
The Card Reader, Model 323, will either: (1) automatically convert 80-column Hollerith card code to RCA 301
characters for transfer to the HSM, or (2) read a punch card image into HSM binarily where it can be processed,
in any desired manner, under program control. This reader reads by row at a rate up to approximately 600 cards per
minute with 20 milliseconds of free computing time between cards. The Card Reader, Model 323, can be instructed
to maintain a 300 card-per-minute rate, resulting in 120 milliseconds of free computing time between cards.
The Card Reader, Model 323, feed hopper can hold up to 2,000 cards. Two card reading stations within this
reader provide an automatic hole count check. Capacity of the reject stacker is approximately 100 cards. Cards may be
loaded and unloaded for continuous operation. The Card Reader, Model 323, has facilities for sensing empty input
hopper, full output stacker, full reject stacker and card jams, and will stop the computer if any of these conditions
exist.
The Card Reader, Model 324, under program control will: (1) automatically convert 80-column Hollerith card
code to RCA 301 characters for transfer to HSM, or (2) read a punch card image into HSM binarily which can be
processed in any desired manner. Cards may be read on demand at rates of up to 900 cards per minute. Reading is
accomplished by photo-electric sensing diodes.
Normally, the card read instruction occupies the mode (Normal or Simultaneous) for the entire card read time.
However, a read release option is available which will permit the feed access time (approximately 18.5 ms) to be
used for other operations.
The Card Reader, Model 324, has an input hopper which has the capacity to hold 2,000 cards. This hopper
can be replenished while the machine is running provided the card level has not fallen below 100 cards. There are
two output stackers—a main stacker and a reject stacker. The main output stacker has a capacity of 2,400 cards.
The reject stacker can accommodate 500 cards.
The Card Reader, Model 329, under program control will: (1) automatically convert 80-column Hollerith card
code to RCA 301 characters for transfer to HSM, or (2) read a punch card image into HSM binarily which can be
processed in any desired manner. Cards may be read on demand at an approximate rate of 1500 cards per minute.
Reading is accomplished by photo-electric sensing diodes.
Normally, the card read instruction occupies the mode (Normal or Simultaneous) for the entire card read time.
However, a read release option is available which will permit the feed access time (approximately 13 ms) to be used
for other operations.
The Card Reader, Model 329, has one input hopper which has the capacity to hold 3,000 cards. There are two
output stackers—the accept stacker and the reject stacker. Each of the output stackers has a capacity of 2,000 cards.
Cards may be loaded or unloaded while the Card Reader is operating.
One model Card Punch, Model 334, punches by row at a rate of 100 cards per minute. The input and output
hoppers have a capacity of approximately 800 cards each. The cards are read after punching to permit an accuracy
check of the punched data. The punch stops upon sensing an empty input or full output hopper.
The second model Card Punch, Model 336, punches by row at a rate of 200 cards per minute. The input and
output hoppers have a capacity of approximately 2,000 cards each. The capacity of the reject stacker is approximately
100 cards. Cards may be loaded or unloaded for continuous machine operation.
Ill

The Card Reader-Punch consists of a card reader and card punch in the same enclosure. The Reader Unit, under
program control, will either: (1) automatically convert 80-column Hollerith card code to 301 code for transfer
to HSM, or (2) read a card image into HSM for processing or translation by program. Reading occurs a row at a
time at rates up to approximately 800 cards per minute, with 10 milliseconds of free compute time per card cycle.
When the read-release program option is exercised, an additional 21 milliseconds of compute time per card cycle is
available. Two read stations permit a hole count accuracy check to be performed.
The Punch Unit punches 80-column cards in either Hollerith or binary code, as specified by the stored program.
Punching is performed at rates up to approximately 250 cards per minute with 22.5 milliseconds of compute t;me
per card cycle. An additional 37 milliseconds of compute time is available when the punch-release program option
is utilized. Verification of the punched data by a read station is performed on the succeeding card punch cycle.
The input hopper of the Reader Unit holds 3,000 cards, and the input hopper of the Punch Unit holds 1,200
cards. There are five output stackers. (Two stackers for the reader, two stackers for the punch; the center stacker
may be selected by either the reader or punch.) Concurrent card reading and punching operations may be performed
when the system includes the Simultaneous Mode Control.
PAPER TAPE EQUIPMENT
The paper tape equipment includes the Paper Tape Reader/Punch, the Paper Tape Reader, the Paper Tape
Punch and the High Speed Paper Tape Punch.
The Paper Tape Reader/Punch is mounted on the same base. The Reader and the Punch both operate at a rate
of 100 characters per second. The unit writes to or reads from 5-channel or 7-channel paper tape. Gapless tape
can be read. The seven channels across the width of the tape correspond to the seven bit positions (six information
and a parity bit) of an RCA 301 character. When a character position on paper tape contains a punch in all seven
channels, it is interpreted as "delete character," it is not an RCA 301 character and no attempt is made to read
it into the Computer. When 5-channel tape is being read, the 2" position is interpreted as a zero bit and correct
parity is placed in the 2° position to result in a 7-bit character being placed in HSM. When punching 5-channel
tape, the 2° and the 2' bits of each character are stripped off after the character is called from HSM resulting in
a 5-bit character being punched on tape. Both reading and punching can progress simultaneously if the System has
a Simultaneous Control Unit. Parity is checked on all information read and on all information received at the Punch.
Packing density is 10 characters per inch. Tape speed is approximately 10 inches per second. The Reader stops on a
character and in a position ready to read the next character. The Stop-Start Distance of the punch is 0.3 inch, or
3 sprocket holes, from the last character punched.
The Paper Tape Reader reads 5, 6, or 7-level paper tape at speeds of approximately 500 or 1,000 characters
per second. When 5 or 6-level tapes are read, additional bits are added in the most significant bit locations to
produce 7-level characters of correct parity to be stored in HSM. At the 500 characters per second rate, the Reader
stops on a character and in a position to read the next character. At the 1,000 characters per second rate, the
Reader stops in a position to read a character at a maximum of 0.3 inch (three sprocket holes) from the last
character read. Packing density on tape is 10 characters per inch, and tape moves at 50 or 100 inches per second. An
adjustable guide is provided to handle tape in widths from
n/16
inch to one inch. Unwind and take-up reels may
be used for reading tape lengths up to 1,000 feet. All small Characters are checked for correct parity.
The Paper Tape Punch punches 5, or 7-level paper tape at speeds of approximately 100 characters per second.
When 5-level tape is punched, the two most significant bits of each 7-bit character received from HSM are ignored
resulting in a 5-bit character to be punched. The Punch stops in a position to punch a character a maximum of 0.3
inch (three sprocket holes) from the last character punched. Packing density on tape is 10 characters per inch,
and tape moves at approximately 10 inches per second. All information received at the Punch is checked for parity.
The High Speed Paper Tape Punch, Model 332, punches 7-level paper tape at a speed of approximately 300
characters per second. There is a combined pushbutton control and indicator on the punch unit. When this is set,
a three-character gap will be generated between blocks of information. When the indicator is reset, the punch will
stop on a character location in position to punch in the next character location.
II-2

ON-LINE PRINTER
Both buffered and unbuffered on-line printers are available in the RCA 301 System. The buffered printers
provide the advantage of off-line scan-print in addition to off-line paper advance, freeing the processor mode on
completion of print table and data line transfer to the buffer. Further, the buffer can be loaded during paper advance
for a prior print instruction.
Two mqdels are available in either the buffered or the unbuffered printers. The important differences between
the two models are (1) the number of characters that can be printed per line, and (2) the number of lines that can
be printed per minute.
One model prints a maximum of 120 characters per line. The printing rate is up to approximately 1000 lines per
minute in the Synchronous Mode which permits the printing of 47 selected characters. The printing rate is up to
approximately 800 lines per minute in the Asynchronous Mode which permits the printing of 64 characters.
The second model prints a maximum of 160 characters per line. The printing rate is up to approximately 1075
lines per minute in the Synchronous Mode and up to approximately 835 lines per minute in the Asynchronous Mode.
The printers can be operated in the following combinations at the indicated speeds:
No. of
Mortal
Synchronous Speed
Asynchronous Speed
Printers
moaei
(Ipm) per Printer
(Ipm) per Printer
Unbuffered
1
120 Column
1,000 (N or S)
800 (N or S)
1
160 Column 1,075* (N)
835* (N)
1
160 Column
715 (N or S)
600 (N or S)
2
120 Column #1
800 (N or S)
#2
800 (N or S)
2
160 Column #1
600 (N or S)
#2
600 (N or S)
Buffered
1
120 Column
1,000 (N or S)
800 (N or S)
1
160 Column
1,075 (N or S)
835 (N or S)
2
120 Column #1
1,000 (N or S)
800 (N or S)
#2
1,000 (N or S)
800 (N or S)
2
160 Column #1
1,075 (N or S)
835 (N or S)
#2
1,075 (N or S)
835 (N or S)
(N)-—Normal Mode
(S)—Simultaneous Mode
* Printing at full speed in the Simultaneous Mode is not possible with the 160-column unbuffered printer due to memory interrupt
requirements. If a card read or punch operation is performed in the "S" Mode concurrently with a print instruction in the "N" Mode
the rates are reduced to 715 and 600 lines per minute (1pm) respectively.
The following characteristics are common to both printers:
The Printer is a transistorized device which prepares output documents, printing data directly from the
High Speed Memory of the Computer. Data editing is accomplished in the Computer under the direction of
the stored program. Paper advance is controlled by the Computer program, either directly or through a
paper tape loop in the Printer. Paper advance is independent of the Computer activity at a rate of 150 lines
a second.
Two Computer instructions are directly associated with the On-Line Printer. One controls the On-Line
Printer in the Normal Mode, the other in the Simultaneous Mode. Variations in these basic instructions
permit printing, paper advance for a specified number of lines, vertical tabbing, or page change. Certain
combinations of these functions are also possible with these instructions.
II-3

Ten characters are printed per horizontal inch and six lines per vertical inch.
In the Synchronous Mode, the Printer will print 26 letters of the English alphabet, the numerals (0 to 9),
and the following 11 punctuation marks and symbols for a total of 47 available characters.
CR
credit
/
virgule
(SP) space
y
apostrophe
a
lozenge
, comma
*
asterisk
—
minus
period
&
ampersand
+
plus
In the Asynchronous Mode, the Printer will print 26 letters of the English alphabet, the numerals (0 to 9),
the above listed 11 punctuation marks and symbols, and the following 17 punctuation marks and symbols
for a total of 64 available characters:
@
at the rate of
:
colon
$
dollar sign
%
percent
#
number
)
close parenthesis
"
quote or ditto
J
semicolon
[
open bracket
10
subscript 10
>
greater than
<
less than
(
open parenthesis
-7"
divide
=
equal
]
close bracket
f
up arrow
For accuracy control, a printer unit inoperable alarm is incorporated which stops both the Printer and the
Computer. Also, by means of a micro-switch, the Printer can sense a "low paper' condition and send a
warning signal to the Computer.
When the Computer program calls for tape loop control of a page change and a "low paper" signal is
present, both the Computer and the Printer stop after accomplishment of the page change and the com-
pletion of any instruction in progress in any other mode, to permit replenishment of the paper supply.
Thus, printing on a page is completed before the operation is stopped.
MONITOR PRINTER
The Monitor Printer is a typewriter-like output device operated under program control. The Tape Write Normal
or Tape Write Simultaneous instructions are used for operation of this device. Characters can be printed at the rate
of up to 10 characters per second. Ten characters are printed per inch, 95 characters per line. Paper may be single
or multiple sheets, up to 11 inches wide. The following pica type characters may be printed:
ABCDEFGHIJKLMNOPQRSTUVWXYZ
0123456789
# @ () = :,%& EB ; EI $"-.•+* ED EF / '
A carriage return is effected by printing an RCA 301 "ED" character or by setting tab stops.
The information is checked for correct parity in the Processor. If the Monitor Printer is inoperable when
addressed, a computer stop occurs.
INTERROGATING TYPEWRITER
The Interrogating Typewriter is an input/output device, operated under control of the stored program, which
allows interrogation of the computer files via a keyboard. The replies are received and typed by the same device.
The program staticizes the Tape Read Forward Normal or the Tape Read Forward Simultaneous instructions to
enter data into the computer. The Tape Write Normal or Tape Write Simultaneous instructions are used to write data
from the computer. The Input/Output Sense instruction is used to sense the status of the Interrogating Typewriter.
II-4