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              POST - Cold Boot / Power On Self Test Activities

        - power supply starts Clock Generator (8284) with Power
          Good signal on BUS
        - CPU reset line is pulsed resetting CPU
        - DS, ES, and SS are cleared to zero

        Cold and Warm Boot both execute the following sequence
        - CS:IP are set to FFFF:0000 (address of ROM POST code)
        - jump to CS:IP  (execute POST, Power On Self test)
        - interrupts are disabled
        - CPU flags are set, read/write/read test of CPU registers
        - checksum test of ROM BIOS
        - Initialize DMA (verify/init 8237 timer, begin DMA RAM refresh)
        - save reset flag then read/write test the first 32K of memory
        - Initialize the Programmable Interrupt Controller (8259)
          and set 8 major BIOS interrupt vectors (interrupts 10h-17h)
        - determine and set configuration information
        - initialize/test CRT controller & test video memory (unless 1234h
          found in reset word)
        - test 8259 Programmable Interrupt Controller
        - test Programmable Interrupt Timer (8253)
        - reset/enable keyboard, verify scan code (AAh), clear keyboard,
          check for stuck keys, setup interrupt vector lookup table
        - hardware interrupt vectors are set
        - test for expansion box, test additional RAM
        - read/write memory above 32K (unless 1234h found in reset word)
        - addresses C800:0 through F400:0 are scanned in 2Kb blocks in
          search of valid ROM.  If found, a far call to byte 3 of the ROM
          is executed.
        - test ROM cassette BASIC (checksum test)
        - test for installed diskette drives & FDC recalibration & seek
        - test printer and RS-232 ports.  store printer port addresses
          at 400h and RS-232 port addresses at 408h.  store printer
          time-out values at 478h and Serial time-out values at 47Ch.
        - NMI interrupts are enabled
        - perform INT 19 (bootstrap loader), pass control to boot record
          or cassette BASIC if no bootable disk found
        - WARM BOOT procedure is now executed

        - see   DIAGNOSTIC CODES