RCA 301 Programmer's Reference Manual
                                                                                                                                                                                                                                           | |
0 Card Read Normal (CRN)General DescriptionThis instruction reads information from punched cards in the Card Reader, Model 323, into the HSM. Facilitiesare provided for reading cards at 600, 300, or 200 cards per minute, or for single card feed on demand.FormatOperation —0 (zero)N — Selects the Card Reader, Model 323, and either determines the rate at which cards are to be reador is used in a card cycle ending routine, according to the following:CardReader Result1 Reads single card or terminates continuous card reading cycle (600 cpm)2 Used in continuous card ending routine (600 cpm)4 Used in continuous card reading cycle (600 cpm)M Used in alternate card reading cycle (300 cpm)8 Terminates alternate card reading cycle (300 cpm)A Address — Address of HSM location to receive the first character read from punched cards.B Address — Must be zeros (0000).Direction of OperationLeft to right.Outline of OperationInitially and thereafter, as the need arises, the instruction automatically directs the Card Reader to place one ormore cards in the read station and operates on successive characters in the following cycle:The character in column one of the punched card is automatically translated from RCA Card Code to RCA301 code and is placed in HSM in the location specified by the A Register. The following 79 characters are placedin successive locations in HSM. The final character (column 80) is located at (A), + 79.In order to maintain a 600 card per minute rate, a Card Read instruction in which the N character is 4 must beexecuted for each card read. The successive card read instructions must be staticized before 100 milliseconds haveelapsed. Approximately 80 milliseconds are required to read one card leaving 20 milliseconds of compute timebetween cards.Continuous card reading is initiated when N = 4. Since only the first of the three cards in the card readertransport mechanism is read by this instruction, the continuous card reading cycle must be terminated by two cardread instructions in which the N characters are 2 and 1 respectively to avoid a "feed" error.The card feed rate may be accomplished at 300 cards per minute by staticizing successive card read instructionsevery 200 milliseconds for each card read. The N character in the card read instructions must be M. Of this 200millisecond card cycle, approximately 120 milliseconds are free for computing after the card has been read.This Alternate Card Reading cycle must be terminated by a Card Read instruction in which the N = 8.When Card Read instructions are staticized in which the N character is 1, cards may be read at any rate up to200 cards per minute. No terminating instruction is necessary since only one card has been fed into the Card Readertransport mechanism by this instruction.VIII-3 |
Related manuals for RCA 301
This manual is suitable for:
manualsdatabase
Your AI-powered manual search engine