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Algorithm to Evaluate the Emulation of IBM 3340/70 on IBM 3344

IP.com Disclosure Number: IPCOM000088964D
Original Publication Date: 1977-Aug-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 72K

Publishing Venue

IBM

Related People

Lee, PC: AUTHOR [+2]

Abstract

This article describes an algorithm for calculating the random intra-data set seek time for a data set of N logical cylinders on a 3344 device, in order to evaluate the emulation of IBM 3340-70's on IBM 3344 devices.

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Algorithm to Evaluate the Emulation of IBM 3340/70 on IBM 3344

This article describes an algorithm for calculating the random intra-data set seek time for a data set of N logical cylinders on a 3344 device, in order to evaluate the emulation of IBM 3340-70's on IBM 3344 devices.

One IBM 3344 has the capacity of four IBM 3340-70's, and each IBM 3344 physical cylinder can be subdivided into five IBM 3340-70 logical cylinders, as is illustrated in the drawings.

The following algorithm, in APL notation, gives the emulated seek time (ESK) for N logical cylinders on an IBM 3344 device ESK[n] = (((0 Not Equal 5 N)x(5-5 Absolute N) Divide 5) x T5K[L(N-1) = 5]) + (((0 = 5 AN) + ((O Not Equal 5 Absolute N) x(5 N) Divide 5)) x TSK(1 + (N - 1) Divide = 5]) where N = the number of logical cylinders 1,2,3,4...; and when N = 0,ESK[0] = TSK[0] = 0, as no physical seek is required; and 5 Absolute N = N module 5; e.g., 5 6 = 1 which is the remainder after computing the integer portion of the quotient N Divide 5; and L(N - 1) Divide 5 = the floor, or integer portion, of (N-1) divide 5; and TSK[x] = travel seek time for x physical records.

The above expression is the individual seek time for N logical cylinders. The random seek time RSK[M] within a data set comprising M logical cylinders is computed by the following expression:

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where N = 1,2,3,...,(M-1).

By way of example, for a data set comprising seven logical cylinders, the random intra-data set seek time RSK[7] i...