Browse Prior Art Database

Diagnostic for Forcing Overrun/Underrun Diskette Checks

IP.com Disclosure Number: IPCOM000044233D
Original Publication Date: 1984-Nov-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Waddell, JM: AUTHOR

Abstract

This article describes a program technique to force error conditions representing a data underrun, which is usually the result of a slow read, or a data overrun, usually the result of a slow write operation when the memory cannot supply data fast enough to verify that the error detecting logic is functioning properly. The basic procedure to force these error conditions, shown in detail in the flowchart, causes the data channel to stop data transfer during a read operation. The steps begin with the diagnostic program setting up a read operation from the diskette to the memory. The read-in area is preset to some value, e.g., 5, the data being read in begin a different value, e.g., 7. By monitoring the memory read-in area, the diagnostic can detect when a data transfer starts.

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Diagnostic for Forcing Overrun/Underrun Diskette Checks

This article describes a program technique to force error conditions representing a data underrun, which is usually the result of a slow read, or a data overrun, usually the result of a slow write operation when the memory cannot supply data fast enough to verify that the error detecting logic is functioning properly. The basic procedure to force these error conditions, shown in detail in the flowchart, causes the data channel to stop data transfer during a read operation. The steps begin with the diagnostic program setting up a read operation from the diskette to the memory. The read-in area is preset to some value, e.g., 5, the data being read in begin a different value, e.g., 7. By monitoring the memory read-in area, the diagnostic can detect when a data transfer starts. Once a data transfer has started into the memory area, the diagnostic invokes a machine check condition. The machine check terminates the data transfer operation so the diskette adapter overflows because it has no destination to which to send the data. Under these conditions, the adapter should generate an overrun error indication. Failure to do so indicates a malfunction in the error detection logic.

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