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Variation of the System Network Architecture IPL Sequence for Use With Devices Not SDLC Attached

IP.com Disclosure Number: IPCOM000046775D
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Day, MN: AUTHOR

Abstract

This article describes an interface used to load program code from a host system to a locally attached device when the device is not SDLC (Synchronous Data Link Control) attached. The general IPL (Initial Program Load) sequence specified by SNA (Systems Network Architecture) was used as a guide in determining the steps in the sequence. Since in this particular case the load sequence is used to load a program into a locally attached feature device, the term Feature Program Load (FPL) is used to differentiate the program load from the system IPL. The FPL sequence consists of four basic commands to the loader, residing in the locally attached device. The FPL-INITIAL command is a three-byte command used to start the program load process. The first byte is the command code, followed by two data bytes.

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Variation of the System Network Architecture IPL Sequence for Use With Devices Not SDLC Attached

This article describes an interface used to load program code from a host system to a locally attached device when the device is not SDLC (Synchronous Data Link Control) attached. The general IPL (Initial Program Load) sequence specified by SNA (Systems Network Architecture) was used as a guide in determining the steps in the sequence. Since in this particular case the load sequence is used to load a program into a locally attached feature device, the term Feature Program Load (FPL) is used to differentiate the program load from the system IPL. The FPL sequence consists of four basic commands to the loader, residing in the locally attached device. The FPL-INITIAL command is a three-byte command used to start the program load process. The first byte is the command code, followed by two data bytes. The two data bytes inform the device to be loaded as to how many bytes of program load are to be transferred in this step. An indicator in the first data byte is also used to instruct the loader to use a default load address or, alternately, to use the contents of a host alterable register as the load address. Once an acknowledgment is received from the device, the established number of bytes of program code is sent to the device. The FPL-TEXT command is a three-byte command used to continue loading program sections to the locally attached device. The program load is broken into multiple sections to keep performance of other devices on the link from dropping due to the potentially large data transmission of a program load. Like the INITIAL command, the first data byte contains an indicator informing the loader to use its current load address or to accept a new load address from a Host alterable register. This feature allows the Host program to load segments into different parts of the attached device's program storage, instead of requiring a straight, time c...