PORTIBM PC Portable (uses same BIOS as XT) 0100-0107 - PS/2IBM PS/2, any model POS (Programmable Option Select)
Note:	the default value for PORTIBM PC Portable (uses same BIOS as XT) 0102h is stored in CMOS(Complementary Metal-Oxide-Semiconductor) A type of integrated circuit design known for its low power consumption. 31h

0100  R	  POS register 0	Low adapter ID byte
0101  R	  POS register 1	High adapter ID byte
0102  RW  POS register 2	option select data byte 1 (see #P0492)
0103  RW  POS register 3	option select data byte 2 (see #P0493)
0104  RW  POS register 4	option select data byte 3
0105  RW  POS register 5	option select data byte 4
		 bit 7	channel active (-CHCK)
		 bit 6	channel status
0106  RW  POS register 6	Low subaddress extension
0107  RW  POS register 7	High subaddress extension


Bitfields for PS/2IBM PS/2, any model POS register 2, option select data byte 1:
Bit(s)	Description	(Table P0492)
 7	  0  = unidirectional LPTAbbreviation for Line PrinTer. port
	  1  = bidirectional LPTAbbreviation for Line PrinTer. port
 6-5	PS/2IBM PS/2, any model Model 50 and higher
	 00b = default LPTAbbreviation for Line PrinTer. port at 3BCh
	 01b = ""		   378h
	 10b = ""		   278h
	 11b = reserved
 4	enable parallel port
 3	serial port address
	=0 COM2 (02F8h, IRQ3)
	=1 COM1 (03F8h, IRQ4)
 2	enable serial port
 1	enable diskette controller
 0	(MCA) =0 override bits 1,2,4 and disable devices
 0	card enable (CDEN)
 0	=1 VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. sleep bit, disconnects output drivers from VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers. (usage for VGAVideo Graphics Array(Video Graphics Array) The video adapter introduced with the IBMInternational Busiuness Machines PS/2IBM PS/2, any model series of computers.
	  without monitor)
---ET4000---
 7-4	reserved???
 3	video RAM(Random Access Memory)	See also DRAM, SRAM. wait enable
 2	ET4000: ROM(Read-Only Memory) A memory for program storage which may not be changed by the program as it runs. BIOS(Basic Input/Output System) A set of standardized calls giving low-level access to the hardware.  The BIOS is the lowest software layer above the actual hardware and serves to insulate programs (and operating systems) which use it from the details of accessing the hardware directly. wait enable
 1	ET4000: I/O wait enable
Note:	access to this port is only possible when PORTIBM PC Portable (uses same BIOS as XT) 0094h bit 7 is low.
SeeAlso: #P0493


Bitfields for Chips&Technologies 64200 "Wingine" setup register:
Bit(s)	Description	(Table P0493)
 7	enable access to extended registers (see #P0762)
Note:	on some C&T graphics chips, this register can be made read-only
	  via XR70 (see #P0762)
SeeAlso: #P0492