Editing IBM PC AT Troubleshooting Guide (section)

=== 1xx &mdash; System board ===

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''5170 1xx system board codes'''
! Code !! Meaning
|-
| 101 || Interrupt failure (8259A PIC)
|-
| 102 || Timer failure (8254 PIT channel 0)
|-
| 103 || Timer interrupt failure
|-
| 104 || Protected mode failure (80286 internal)
|-
| 105 || Last 8042 (keyboard controller) command not accepted
|-
| 106 || Converting logic test (post-protected-mode return)
|-
| 107 || Hot NMI test
|-
| 108 || Timer bus test
|-
| 109 || DMA test error (8237A)
|-
| 110 || System board parity error
|-
| 111 / 112 / 113 || Adapter card parity / I/O channel check
|-
| 121 || Unexpected hardware interrupt occurred
|-
| 129 || Cache error (later board steppings with cache support; unsupported CPU upgrade)
|-
| 131 || Cassette wrap test failed (legacy code, no cassette port on the AT)
|-
| 161 || CMOS configuration empty &mdash; '''battery failure''' or freshly fitted board
|-
| 162 || CMOS checksum error (adapter ID mismatch) &mdash; run SETUP
|-
| 163 || Time and date not set &mdash; run SETUP and re-enter
|-
| 164 || Memory size error &mdash; CMOS does not match installed RAM
|-
| 166 || Adapter card system board error
|-
| 181 || Bad CMOS configuration
|-
| 199 || User-indicated configuration not correct
|}