IBM 560E User Manual
RT/CMOS RAM
The RT/CMOS RAM (real-time clock/complementary metal-oxide
semiconductor RAM) module contains the real-time clock and 128
bytes of CMOS RAM. The clock circuitry uses 14 bytes of this
memory; the remainder is allocated to configuration and
system-status information. A battery is built into the module to keep
the RT/CMOS RAM active when the power supply is not turned on.
semiconductor RAM) module contains the real-time clock and 128
bytes of CMOS RAM. The clock circuitry uses 14 bytes of this
memory; the remainder is allocated to configuration and
system-status information. A battery is built into the module to keep
the RT/CMOS RAM active when the power supply is not turned on.
Figure 2-12 lists the RT/CMOS RAM bytes and their addresses.
Figure
2-12. RT/CMOS RAM Address Map
Address (Hex)
RT/CMOS RAM Bytes
000–00D
Real-time clock
00E
Diagnostic status
00F
Shutdown status
010
Diskette drive type
011
Hard disk 2 and 3 drive type
012
Hard disk 0 and 1 drive type
013
Reserved
014
Equipment
015, 016
Low and high base memory
017, 018
Low and high expansion memory
019
Hard disk 0 extended byte
01A
Hard disk 1 extended byte
01B
Hard disk 2 extended byte
01C
Hard disk 3 extended byte
01D–02D
Reserved
02E, 02F
Checksum
030, 031
Low and high usable memory above 1MB
032
Date-century
033–07F
Reserved
2-16
ThinkPad 560/560E System Board