Mitsubishi Electric Apricot LS Pro, Техническое описание оборудования

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Chapter 1
Chapter 2
Chapter 6
Contents
Chapter 3
Chapter 5
System Board
Chapter 3
LS PRO HARDWARE TECHNICAL REFERENCE 3/11
Real time clock (RTC) RAM
The real time clock and its associated battery backed RAM is an MC146818. The RTC
RAM is accessed via I/O ports 0070h and 0071h. The first fourteen bytes are used to
store real time clock information, the remainder are used for system configuration
data.
The RTC is normally powered from the 5V supply. However when the
computer is not switched on power is supplied by a rechargeable battery on
the system board. This maintains the correct time and configuration information.
If the battery becomes discharged the time and date will need to be reset and
the system will need to be reconfigured using the SETUP utility.
Contents of The contents of the RTC RAM are listed below.
RTC RAM
Address Function Address Function
Real time clock data 16 Base memory (high byte)
00h seconds 17
Expected expanded memory
(low byte)
01h alarm seconds 18
Expected expanded memory
(high byte)
02h minutes 19 Drive type for hard drive 0
03h alarm minutes 1A-1E Reserved
04h hours 1F shadow BIOS
05h alarm hours 20-27 Reserved
06h day of week 28 Apricot sound volume
07h date 29 Apricot options
08h month 2A Apricot boot type
09h year 2B
Apricot cache disable
(see also byte 34h)
0Ah status register A 2C-2D Reserved
0Bh status register B 2E High byte checksum for 10-2D
0Ch status register C 2F Low byte checksum for 10-2D
0Dh status register D 30
Actual expanded memory
(low byte)
0E Diagnostic Status 31
Actual expanded memory
(high byte)
0F Shutdown code 32 Century in BCD
Configuration data 33
Memory exceeds 512K/387
presence
10 Diskette drive type 34
486SLC cache control
(see also Apricot byte 2Bh)
11 Reserved 35 Apricot access rights
12 Fixed disk drive type 36 Floppy/Token-Ring autodetect
13 Power on password 37 Hard disk autodetect
14 Equipment byte 38-3E Power on password
15 Base memory (low byte) 3F Byte checksum of bytes 38-3E