Zenith Z-100 Series, Technical Manual

Page: 449 / 493

Page 10.23
Z-DOS INITIALIZATION SEQUENCE
On return from DOS INIT, IO.SYS turns on the keyboard,
and then uses the appropriate function calls to load and exe-
cute the file COMMAND.COM. Once COMMAND.COM is
loaded, control is passed to it, at which point it initializes itself,
prints its header, checks for AUTOEXEC.BAT, gets the date
and time from the user, and prints the system prompt. Then
the operating system is fully in control, and the user is ready
to begin executing programs. (See Pictorial 10-6.)
TOP OF MEMORY (SYSTEM ROM)
— TOP OF RAM
COMMAND. COM TRANS IENT ( MAY BE
OVERLAYED BY USER PROGRAMS)
-USER PROGRAM TPA AREA
-COMMAND. COM RES IDENT PORTION
-Z-DOS TABLES AND BUFFERS
-Z-DOS. SYS
-IO. SYS WORK SPACE (SIZE VARIES)
-FILE IO, SYS
-40:0 (SAVE AS 0:400) (1K)
0;0
Pictorial 10-6
Initialization Complete