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EXECUTE INTERNAL DIAGNOSTICS - 14100_222
Minicomputers - 14100_224

Fire Controlman Volume 03-Digital Data Systems
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The ROM-based diagnostics menu provides you access to the following types of tests, again depending on the type of computer and the system configuration: disk  read,  keyboard,  base  memory,  expansion  memory, printer, and power on. Additional   board   mounted   diagnostic light-emitting diode (LED) indicators (fig. 8-24) are normally provided on the computer backplane and I/O logic  circuit  modules.  This  simplifies  the  diagnostic software and aids in fault isolation and identification. The  LEDs  on  the  backplane/motherboard  for  power remain on as long as the microcomputer is on. The LEDs  on  the  I/O  pcb  extinguish  as  each  test  is successfully completed, except the READY LED. It will extinguish after an operating system is read from disk. The features of ROM-based diagnostics of micros differ  based  on  manufacturer  and  system  configuration. They are normally designed to provide at least 90% Figure  8-24.—Examples  of  LED  indicators. resolution on detected faults to a single large scale integration  (LSI)  circuit  or  supporting  integrated circuits. RAM and ROM errors are usually identifiable to  the  specific  IC  chip.  The  ROM-based  diagnostics  are designed to verify and fault isolate enough of the computer’s logic to allow for loading and executing more  comprehensive  diagnostic  programs  stored  on disk (floppy or hard disks). EXECUTE    BOOTSTRAP.    —Micros    are normally  designed  to  boot  or  initially  load  the  disk operating  system  (DOS)  program  from  either  the installed floppy or hard disk assemblies, based on the system  configuration.  The  operating  system  program provides  for  operator  control  of  the  loading  and executing of application programs used within the microcomputer system. There are two ways to boot a micro. Firmware stored in PROM or ROM will automatically reference the configured disk for the operating system program as part of the power on sequence. Turn the micro ON and  it  automatically  looks  for  the  operating  system program on the configured disk. If it finds it, the operating system automatically loads. If it does not find it, you will need to ensure the disks are setup correctly and depress a combination of keys to cause the system to boot. INITIATE  OPERATIONAL  PROGRAMS.  — For microcomputers, once the microcomputer has been booted, how the computer is configured will dictate how to initiate the operational program, the software, to be  used. EXECUTE   AUTO   RESTART   OPERA- TIONS. —There is also a particular combination of keyboard keys (such as Ctrl, Alt, and Del) that will cause the operating system program to reboot and restart. This can be used in the event of a software failure. You can also reboot by turning the computer OFF and then ON. EXECUTE DIAGNOSTICS.  —YOU can load and execute disk based diagnostics using DOS command structures  or  a  diagnostic  monitor  program.  To  execute these, you usually load the programs by a different power-up and boot sequence. The diagnostic monitor program displays a  test selection menu  similar to the internal  diagnostic  menu.  Because  these  diagnostics are   more   comprehensive   than   the   ROM-based diagnostics, you will be given more information on the menu than you are with the ROM driven display. The test selection menu provides for  diagnostic  selection, test status, and error indications.  The selection, test 8-19






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