Does anyone know where I can find a list of what the digital display codes mean. Have a NAM showing 7C and stopped working. Doesn't go thru proper startup sequence and F9xx doesn't work.
There are 5 green LED,s on the lower left corner of the backplane. Each one is connected to a different output to provide a visual indication for each power supply voltage.
From top to bottom they are:
LED 3 3.3 volts
LED 5 -5.0 volts
LED 1 5.0 volts
LED 4 -12.0 volts
LED 2 12.0 volts
Port 80 Codes
the diagonostic port is an I/O port used for diagnostic assistance. The BIOS can write codes to this port which are displayed in hexadecimal notation. These codes can be used to identify errors that cause the system to halt. This includes beep codes, which also create an audible sound from the speaker.
Note that many of the codes appearing briefly on the display do not halt the system. They are, to report flow control, and will not be documented here. The codes which cause the system to halt and beep are as follows:
Code Beep Description
19 2-3-2 Screen memory test
1A 2-3-2 Screen retrace test
27 3-2-4 CMOS mem compare
28 3-3-1 Mem size mismatch
7A Bad sector on hard drive
7F Disk in Floppy Drive
82 1-1-3 CMOS write&read-back failure
83 1-1-4 BIOS ROM checksum failure
84 1-2-1 Programmable Interval Timer test failure
85 1-2-2 DMA initialization failure
86 1-2-3 DMA page register write & read-back failure
87 1-2-4 DRAM refresh verification failure
88 1-3-1 First 64K RAM test failure
89 1-3-2 First 64K RAM parity check failure
90 2-1-1 Slave DMA register test failure
91 2-1-2 Slave DMA register test failure
92 2-1-3 Master interrupt mask register test failure
93 2-1-4 Slave interrupt mask register test failure
95 2-2-2 Keyboard controller test failure
9C Trying to boot a NAM that is less than 4.0 on a 4.0 or greater Norstar.
A0 3-1-1 Timer tick interrupt, test failure
A1 3-1-2 Timer Ch.2 test failure
A3 3-1-4 Time of Day clock test failure
Other miscellaneous codes
Code Description
01 Power Management level 1
02 Power Management level 2
03 Power Management level 3
9C Video Error
Another use for the port 80 display will be to blink, out the Setup and POST (Power On Self Test) error codes when a monitor is not connected. These error codes are generated by BIOS and are normally seen on the monitor screen (162 setup error, etc.).
If the system displays Setup and POST errors on the screen, it also begins blinking out the two byte codes to the port 80 display over and over. For example, if there is a 0162 (setup error) and a 0604 (diskette error) would be seen on the port 80 display. Change CPU switch 5 to display codes.
Port 80 Meaning
EE Error header
01
62 162 error
setup error
FE Error header
06
04 604 error
diskette error
Repeat list of codes
EE Error header
17
80 1780 error
hard drive error
Each number is displayed for 1-2 seconds and is repeated until you hit a key. In the keyboardless environment, you then either set the auto-config switch (Dip switch 5) and re-boot, or use a reference diskette to fix the problems.
If the auto-cfg switch is already set, then the error log will not be displayed because BIOS will immediately try to reconfigure and re-boot.
Generic POST error codes will not be listed in thsi document, but are available from several sources, including the IBM web-site: "
Once POST completes the user can use PORT 80 to display other Messages. Such as system status. User codes should be written in a way that avoids confusion with POST error codes.
Note: 00 is the mormal operating display after POST is completed.
I almost remember 7c being a monitor package error.Does the nam continue to go to floppy drive if so try putting keyboard monitor and mouse then re boot
Company has convinced them to upgrade to CP 100/150.
NAM was working fine for 4yrs...never had a svc call...just stopped working. I did a reboot and normally it gives you a series of tones while going thru the startup sequence but in this case it didn't. Within 30s or less it stopped trying to reboot and gave error code 7C. since the NAM has been MD'd by Nortel, probably cheaper to replace w/ CP.
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