Mitsubishi Electric Apricot LS Pro, Hardware Technical Reference

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Chapter 4
Chapter 6
Memory and I/O Usage
Appendix A
Appendix C
Pr
eface
Chapter 4Chapter 5
LS PRO HARDWARE TECHNICAL REFERENCE 5/9
RTC RAM/NMI mask
This port at I/O location 0070h controls the NMI mask and the index register for
accessing the RT/CMOS RAM. The bit significance is given below.
7 6 5 4 3 2 1 0
RT/CMOS RAM
NMI mask
Bits 0-6 These bits define the RT/CMOS RAM location to be accessed by the
following read/write operation to 0071h.
Bit 7 With this bit set to 1 Non-maskable interrupts (NMI) are enabled. With
this bit set to 0 NMI is disabled. A system reset sets this bit to 0.
The RT/CMOS RAM has a data port at I/O location 0071h. the following table lists the
contents of the CMOS RAM.
Address Function
Real time clock data
00h seconds
01h alarm seconds
02h minutes
03h alarm minutes
04h hours
05h alarm hours
06h day of week
07h date
08h month
09h year
0Ah status register A
0Bh status register B
0Ch status register C
0Dh status register D
0Eh Diagnostic status
0Fh Shut-down status
Configuration data
10h diskette drive
11h first hard disk drive
12h second hard disk drive
13h reserved
14h equipment installed
15h memory size in K (low byte)
16h memory size in K (high byte)
17h expanded memory size in K (low byte)
18h expanded memory size in K (high byte)
19h-31h reserved
32h-33h configuration CRC
34h-36h reserved
37h date century
38h-3Eh reserved
3Fh checksum