Browse Prior Art Database

Dynamic Shift Register Memory

IP.com Disclosure Number: IPCOM000078266D
Original Publication Date: 1972-Dec-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 3 page(s) / 49K

Publishing Venue

IBM

Related People

Padden, JT: AUTHOR [+3]

Abstract

A Dynamic Shift Register Memory (DSRM), typically connected between a keyboard, a printer, and a serial storage media, not shown, utilizes four communication flags CF1 - CF4, enabling the system to operate in a communications mode. Rather than using four separate codes for CF1 CF4, a single code is used and a counter distinguishes the communication flags.

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Dynamic Shift Register Memory

A Dynamic Shift Register Memory (DSRM), typically connected between a keyboard, a printer, and a serial storage media, not shown, utilizes four communication flags CF1 - CF4, enabling the system to operate in a communications mode. Rather than using four separate codes for CF1 CF4, a single code is used and a counter distinguishes the communication flags.

In the communications mode, record flag R and operational flag F, also used in the noncommunications mode, are used in conjunction with CF1 - CP4 to divide the DSRM into transmit and receive sections, and to subdivide these sections into subsections of: (a) data codes to be transmitted, (b) data codes which have been transmitted, (c) data codes which have been transmitted and checked, (d) data codes which have been received, (e) data codes which have been received and printed, and (f) data codes which have been received, printed, and checked.

A cleared DSRM in the communications mode is shown in Fig. 1, with the DSRM containing R, CF1, CF2, CF3, CF4, F, and dummy codes D. Data codes to be transmitted may be read from the serial storage media and each code is written into the DSRM, immediately to the left of the first D to the right of F, as shown in Fig. 2. Thus, information to be transmitted is found in the DSRM between F and the first D to the right of F.

F is used as the transmit flag and is moved to the riqht around each character as it is transmitted. Fig. 3 shows the DSRM after the data codes have been transmitted. The substitution of the DSRM containing transmitted data codes is between CF4 and F.

If the transmission was without error, CF4 is shifted adjacent to F, as shown in Fig. 4, so that the subsection of the DSRU between CF3 and CF4 contains data codes that have been transmitted and checked. If an error did occur during the transmission, CF4 is not shifted and F is shifted back to the beginning of the data codes, as shown in Fig. 2, so that the data may be retransmitted.

CP3 separates the transmit and receive sections of the DSRM. In Fig. 5, each data code received is written into the DSRM immediately to the left of CF3. Therefore, the subsection of the receive section that contains received data codes is found between CF2 and CF3.

CF2 serves as the print flag and is shifted to the right around each data code as it is printed. In Fig. 6, the received and printed data codes are found between CF1 and CF2.

If no errors occurred during receiving, CF1 is shifted to the right adjacent CP2 so that the subsection of the receive section of the DSRM between R and CF1...