Browse Prior Art Database

Data Transfer Between Asynchronous Devices Without External Buffering

IP.com Disclosure Number: IPCOM000085924D
Original Publication Date: 1976-Jun-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 13K

Publishing Venue

IBM

Related People

Brock, RL: AUTHOR

Abstract

The method relates to the data rate matching of a source to a sink and, more particularly, to matching the data rate of characters copied from a disk system rotating at a constant speed for recording on a lower data rate system, such as magnetic tape. Broadly, matching of data rates is accomplished by "slowing down" a high-speed source through the introduction of a delay between the source and the sink.

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Data Transfer Between Asynchronous Devices Without External Buffering

The method relates to the data rate matching of a source to a sink and, more particularly, to matching the data rate of characters copied from a disk system rotating at a constant speed for recording on a lower data rate system, such as magnetic tape. Broadly, matching of data rates is accomplished by "slowing down" a high-speed source through the introduction of a delay between the source and the sink.

Alternatively, it is sometimes possible to physically vary the rate of the generation of source information. In this latter sense, H. Blasbalg in USP 3,534,264 and Sullivan, USP 3,536,840, show the adjustment of data rate from a source to a sink (receiver) over a noisy channel as an inverse function of signal error and distortion as measured at the sink, the adjustment being controlled by a signal transmitted over a narrow band feedback path from the sink to the receiver. Reference may also be made to R. A. Lieberman et al, IBM Technical Disclosure Bulletin, Vol. 6, No. 10, March 1964, pp. 112-113, which shows source rate variation for different lengths of time.

In contrast to changing the source rate directly; the prior art also has taught the use of external buffers between the source and the channel/sink. However, external buffering imposes substantial additional hardware and control costs. It is desired to transfer data without external buffer from, for example, a disk-based storage system in which it is also desired to keep the disk rotating at a constant rate, and both read data out at a maximum and less than a ma...