Compaq MSB900L user manual Digital-Logic Ag, MSB900/L Detailed Technical Manual

DIGITAL-LOGIC AG MSB900/L Detailed Technical Manual V1.0

CMOS Map continued...

Location	Description
15h	Base Memory Size (in kB) - Low Byte
16h	Base Memory Size (in kB) - High Byte
17h	Extended Memory Size (in kB) - Low Byte
18h	Extended Memory Size (in kB) - High Byte
19h	Extended Drive Type - Hard Drive 0
1Ah	Extended Drive Type - Hard Drive 1
1Bh	Custom and Fixed (Hard) Drive Flags
	Bits 7-6	= Reserved
	Bit 5	= Internal Floppy Disk Controller
		0	=	Disabled
		1	=	Enabled
	Bit 4	= Internal IDE Controller
		0	=	Disabled
		1	=	Enabled
	Bit 3	= Hard Drive 0 Custom Flag
		0	=	Disabled
		1	=	Enabled
	Bit 2	= Hard Drive 0 IDE Flag
		0	=	Disabled
		1	=	Enabled
	Bit 1	= Hard Drive 1 Custom Flag
		0	=	Disabled
		1	=	Enabled
	Bit 0	= Hard Drive 1 IDE Flag
		0	=	Disabled
		1	=	Enabled
1Ch	Reserved
1Dh	EMS Memory Size Low Byte
1Eh	EMS Memory Size High Byte
1Fh - 24h	Custom Drive Table 0
	These 6 Bytes (48 bits) contain the following data:
	Cylinders			10bits	range 0-1023
	Landing Zone			10bits	range 0-1023
	Write Precompensation			10bits	range 0-1023
	Heads			8bits	range 0-15
	Sectors/Track			8bits	range 0-254
	Byte 0
1Fh	Bits 7-0	= Lower 8 bits of Cylinders
	Byte 1
20h	Bits 7-2	= Lower 6 bits of Landing Zone
	Bits 1-0	= Upper 2 bits of Cylinders
	Byte 2
21h	Bits 7-4	= Lower 4 bits of Write Precompensation
	Bits 3-0	= Upper 4 bits of Landing Zone

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