
** DIFFERENCES BETWEEN THE INSTALLATION GUIDE AND THE INSTALLATION **

	Due to a lag in our documentation preparation, certain detail aspects
of MTOS-86UP V3.1 installation do not agree with the Installation Guide. Those
aspects are:

	1) Certain symbols which were once defined in ABSDEF.ASM, and are
still referred to by the Installation Guide as residing there, have been moved
to the HWDEP.ASM file, the new residence of all hardware-dependencies. Those
symbols are:
	-X_PIT_CMD, the command port address for the 8253 PIT,
	-X_PIT_DATA, the data port address for the 8253 PIT,
	-PIT_RATE, the number of minor clock cycles required by the PIT to
	 count up to 1 millisecond,
	-X_PIT_MS, the size of a clock tick in milliseconds,
	-X_PIC_BASE, the base vector number of the 8259A PIC's block of inter-
	 rupt vectors,
	-X_PIC_EOI, the end-of-interrupt command used to dismiss the current
	 level of interrupt at the 8259A PIC,
	-X_PIC, the port address of the primary command port on the 8259A PIC.

	2) The file HWDEP.ASM now contains all hardware-dependent Nucleus code.
This includes:
	-X_INIT_PIC, the 8259A PIC initializer,
	-X_PIT_INIT, the initializer for the 8253 PIT,
	-X_ISSUE_EOI, a routine whose responsibility is to issue an end-of-in-
	 terrupt sequence to clear the current level of interrupt from the PIC
	 when required,
	-X_SYSOUT, a routine to perform emergency output to the system console.

	Please note that the functions of the abovementioned symbols and rou-
tines are the same as documented in the Installation Guide; only their loca-
tion in the package has been changed. The X_ISSUE_EOI routine replaces the se-
quence of instructions:

		MOV	AL,LOW X_PIC_EOI
		OUT	LOW X_PIC,AL

in the routines X_XEL and X_SYSTATE in STATES.ASM, and in X_PIT_INT in PIT.ASM.
Of course, these routines are to be customized to port MTOS-86 to other hard-
ware environments.
