AT&T 3B2/300 Technical Reference Manual page 578

Appendix: VIRTUAL ADDRESS SPACE - - - - - - - - - - - - - - - - - - - - - - -
SECTION 3 USER VIRTUAL ADDRESS SPACE
VIRTUAL SEGMENT SECTION SEGMENT SEGMENT LOADER
ADDRESS SIZE NAME CONTENTS ACCESS
OPTION
Ox COOOOOOO
1 BYTE USER U_BLOCK KRW
Ox C0020000 USER STACK DATA KRW/URW
LEGEND:
KRW KERNEL READ/WRITE
URW USER READ /WRITE
Figure A-5: Virtual Address Space - Section 3
Paging Virtual Address Space
Figure A-6 shows the minimal virtual address map for a 3B2 computer running a paging operating
system.
PAGING VIRTUAL ADDRESS SPACE
ADDRESS DESCRIPTION
Ox 00000000-0x 7FFFFFFF OPERA TING SYSTEM
Ox 80000000-0x 807FFFFF RESERVED
Ox 80800000-0x 9FFFFFFF
Start of the user . text segment. At next 512 KB boundary (after end of text)
.data begins. The .data segment typically grows toward higher addresses as
a process executes.
Ox OAOOOOOOO-Ox BFFFFFFF RESERVED
Ox COOOOOOOO-Ox DFFFFFFF RESERVED
Ox EOOOOOOOO-Ox FFFFFFFF RESERVED
Figure A-6: Paging Virtual Address Map (Minimum Configuration)
A-4 TECHNICAL REFERENCE MANUAL