2.2 The IBM 7171 ASCII Device Attachment Control Unit - Index of

For demonstration purposes, we will describe the entering of one node of anInput Parse Table. Assume that you want to enter at the locationX' DCOO:07 A2' the node "ESC OOTO IBMESC." The sequence of MaintenanceFacility commands to accomplish this is:s DCOO:07 A2 IBs DCOO:07A3 00sw DCOO:07 A4 5482;ESC=X' IB';This the OOTO address IBMESCThis node is equivalent to the first node in Figure 4-4 on page 4-35. Notethat this figure contains a byte for byte representation of 7171 memory andthat the OOTO address is stored in byte reversed notation.Whenever an address or pointer is read in a byte by byte manner, then anybytes that where written as a word are reversed with respect to their intendedorder. For example we could read in the parse table node we wrote out twoways: byte by byte or exactly the way it was written, namely 2 bytes and aword.For byte display, issuing the command:m DCOO:07 Al 4would display:DCOO:07AIIBOO 8254The address is retrieved byte reversed. To retrieve exactly what was writtenwe have to issue the following sequence of commands:m DCOO:07 Al 2mw DCOO:07A3which would output:Examples of Modifying Host Translate TablesDCOO:07 Al IBOODCOO:07 A3 54828. Add the terminal name to the Terminal Names List which begins atX' DCOO:300' .Example 1: Here is an example of changing the host translate tables by copyingareas of ROM into NV-RAM using the Maintenance Facility. The goal is to createa set of translation tables for 3278 emulation that change the EBCDIC upper caseA to an ASCII lower case a, and EBCDIC lower case a to ASCII upper case A.The default 3278 emulation translate tables map the EBCDIC upper case to ASCIIupper case, and the EBCDIC lower case to ASCII lower case.)Here are the steps involved:1. To make this change smoothly, the user will need theHOST_WRITE_3278_EBCDIC_TO_ASCII table copied intoNV -RAM. This table is 256 bytes long. The user will also need a copy of theChapter 4. Customizing IBM 7171 Tables 4-59