4 BIOS overview
order in which the POST tests are performed
11 |
| Going to check pressing of <INS> , <END> key during |
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12 |
| To init CMOS if "Init CMOS in every boot" is set or <END> key is pressed. Going to disable DMA |
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| and Interrupt controllers. |
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13 |
| Video display is disabled and |
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14 |
| 8254 timer test about to start. |
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19 |
| About to start memory refresh test. |
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1A | Memory Refresh line is toggling. Going to check 15us ON/OFF time. |
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23 |
| To read 8042 input port and disable Megakey GreenPC feature. Make BIOS code segment |
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| writeable. |
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24 |
| To do any setup before Int vector init. |
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25 |
| Interrupt vector initialization about to begin. To clear password if necessary. |
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27 |
| Any initialization before setting video mode to be done. |
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28 |
| Going for monochrome mode and color mode setting. |
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2A | Different BUSes init (system, static, output devices) to start if present. (Please see Appendix for |
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| details of different BUSes). |
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2B | To give control for any setup required before optional video ROM check. |
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2C | To look for optional video ROM and give control. |
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2D | To give control to do any processing after video ROM returns control. |
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2E | If EGA/VGA not found then do display memory R/W test. |
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2F | EGA/VGA not found. Display memory R/W test about to begin. |
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30 |
| Display memory R/W test passed. About to look for the retrace checking. |
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31 |
| Display memory R/W test or retrace checking failed. To do alternate Display memory R/W test. |
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32 |
| Alternate Display memory R/W test passed. To look for the alternate display retrace checking. |
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34 |
| Video display checking over. Display mode to be set next. |
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37 |
| Display mode set. Going to display the power on message. |
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38 |
| Different BUSes init (input, IPL, general devices) to start if present. (Please see Appendix for details |
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| of different BUSes). |
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39 |
| Display different BUSes initialization error messages. (Please see Appendix for details of different |
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| BUSes). |
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3A | New cursor position read and saved. To display the Hit <DEL> message. |
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40 |
| To prepare the descriptor tables. |
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42 |
| To enter in virtual mode for memory test. |
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40