8642 Common Devices

Exploded View
Front Panel
Status LEDs and Information Panel
I²C Bus


Exploded View (codename "Caverun")


Front Panel


Status LEDs and Information Panel

Status LEDs

Green = proper operation, Yellow = alert condition

LED# Definition
1 Hard disk drive activity
2 DASD error
3 Processor Complex Error
4 Color green (POWER GOOD)
5 Color green (POWER Enabled)
6 Color green (All subsystems good)

Error Codes

General Errors
Corollary Errors (CP,TP,EP,IP,FP,HALT)
PCI Errors (DDDD DD S 0 VVVV IIII)

Liquid Crystal Display

The Liquid Crystal Display (LCD) on the front operator panel contains a 2-line by 16-character LCD (front panel display) driven by the 80C752 microprocessor. The front panel display receives and transmits ASCII characters. The LCD supports the upper-and lower-case ASCII character set.

Errors detected by the computer might be displayed on the LCD and/or on the standard display attached to the computer. This is helpful when a display is not attached to the computer or the attached display is inoperative.

LEDs - System Board and Adapter

LED(s) are located on planar, bridge, processor, and memory card.

Component LED On LED Off
Planar Slot LEDs: B1 (bridge card slot) During / after normal initialization of bridge card -SW problem preventing initialization of card
-Defective LED
-Defective bridge card
M1
(memory card slot)
During initialization of memory card Successful initialization of memory card complete
M2/P1
(w/ memory card installed)
During initialization of memory card Successful initialization of memory card complete
M2/P1
(w/ processor card installed)
During initialization and activity on processor card - No activity on processor
- SW problem preventing initialization of card
- Defective LED
- Defective processor card
P2 thru P6
(with processor card installed)
During initialization and activity on processor card -No activity on processor
- SW problem preventing initialization of card
- Defective LED
- Defective processor card
Micro Channel slots When computer is powered-off When computer is powered-on
Bridge card LED During / after normal initialization of bridge card - SW problem preventing initialization of card
- Defective LED
- Defective bridge card
Memory card LED(s) During initialization of memory card Successful initialization of memory card complete
Processor card LED(s) During initialization and activity on processor card -No activity on processor -SW problem preventing initialization of card
-Defective LED
-Defective processor card


I²C Bus (Inter-Integrated Circuit)

The I²C (Inter-Integrated Circuit) bus is a serial bus that is used in the PC Server 720 to monitor and control several peripheral functions within the machine. The bus is driven through a VLSI module on the system board. A service processor on the system board (based on the Intel 83C552 micro-controller) controls and monitors these functions within the machine through the I²C bus. These include:

  • The front panel LCD
  • The front panel power controls
  • Detecting the setting of the SCSI ID jumper on the hot-swap backplanes
  • Reading the voltage and temperature sensors on the planar (viewable using NetFinity)
  • Controlling the three fans mounted behind the drive bays.

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Louis F. Ohland, Peter H. Wendt, David L. Beem, William R. Walsh, Tatsuo Sunagawa, Tomáš Slavotínek, Jim Shorney, Tim N. Clarke, Kevin Bowling, and many others.

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Last update: 20 Jan 2024 - Changelog | About | Legal & Contact