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1993-08-01
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[This file was provided by Wim Osterholt (2:512/56.198).]
Last Change: 8/1/93
XT, AT and PS/2 I/O port addresses
Do NOT consider this information as complete and accurate.
If you want to do harware programming check ALWAYS the
appropriate data sheets. Be aware that erroneously programming
can put your hardware or your data at risk.
-------------------------------------------------------------------------------
0000-001F ---- DMA 1 (first Direct Memory Access controller 8237)
0000 r/w DMA channel 0 address byte 0, then byte 1.
0001 r/w DMA channel 0 word count byte 0, then byte 1.
0002 r/w DMA channel 1 address byte 0, then byte 1.
0003 r/w DMA channel 1 word count byte 0, then byte 1.
0004 r/w DMA channel 2 address byte 0, then byte 1.
0005 r/w DMA channel 2 word count byte 0, then byte 1.
0006 r/w DMA channel 3 address byte 0, then byte 1.
0007 r/w DMA channel 3 word count byte 0, then byte 1.
0008 r DMA channel 0-3 status register
bit 7 = 1 channel 3 request
bit 6 = 1 channel 2 request
bit 5 = 1 channel 1 request
bit 4 = 1 channel 0 request
bit 3 = 1 channel terminal count on channel 3
bit 2 = 1 channel terminal count on channel 2
bit 1 = 1 channel terminal count on channel 1
bit 0 = 1 channel terminal count on channel 0
0008 w DMA channel 0-3 command register
bit 7 = 1 DACK sense active high
= 0 DACK sense active low
bit 6 = 1 DREQ sense active high
= 0 DREQ sense active low
bit 5 = 1 extended write selection
= 0 late write selection
bit 4 = 1 rotating priority
= 0 fixed priority
bit 3 = 1 compressed timing
= 0 normal timing
bit 2 = 1 enable controller
= 0 enable memory-to-memory
0009 w DMA write request register
000A r/w DMA channel 0-3 mask register
bit 7-3 = 0 reserved
bit 2 = 0 clear mask bit
= 1 set mask bit
bit 1-0 = 00 channel 0 select
= 01 channel 1 select
= 10 channel 2 select
= 11 channel 3 select
000B w DMA channel 0-3 mode register
bit 7-6 = 00 demand mode
= 01 single mode
= 10 block mode
= 11 cascade mode
bit 5 = 0 address increment select
= 1 address decrement select
bit 3-2 = 00 verify operation
= 01 write to memory
= 10 read from memory
= 11 reserved
bit 1-0 = 00 channel 0 select
= 01 channel 1 select
= 10 channel 2 select
= 11 channel 3 select
000C w DMA clear byte pointer flip-flop
000D r DMA read temporary register
000D w DMA master clear
000E w DMA clear mask register
000F w DMA write mask register
-------------------------------------------------------------------------------
0010-001F ---- DMA controller (8237) on PS/2 model 60 & 80
-------------------------------------------------------------------------------
0018 w PS/2 extended function register
-------------------------------------------------------------------------------
001A PS/2 extended function execute
-------------------------------------------------------------------------------
0020-003F ---- PIC 1 (Programmable Interrupt Controller 8259)
0020 w PIC initialization command word ICW1
bit 7-5 = 0 only used in 80/85 mode
bit 4 = 1 ICW1 is being issued
bit 3 = 0 edge triggered mode
= 1 level triggered mode
bit 2 = 0 successive interrupt vectors use 8 bytes
= 1 successive interrupt vectors use 4 bytes
bit 1 = 0 cascade mode
= 1 single mode, no ICW3 needed
bit 0 = 0 no ICW4 needed
= 1 ICW4 needed
0021 w PIC ICW2,ICW3,ICW4 after ICW1 to 0020
ICW2:
bit 7-3 = address lines A0-A3 of base vector address for PIC
bit 2-0 = reserved
ICW3:
bit 7-0 = 0 slave controller not attached to corresponding
interrupt pin
= 1 slave controller attached to corresponding
interrupt pin
ICW4:
bit 7-5 = 0 reserved
bit 4 = 0 no special fully-nested mode
= 1 special fully-nested mode
bit 3-2 = 0x nonbuffered mode
= 10 buffered mode/slave
= 11 buffered mode/master
bit 1 = 0 normal EOI
= 1 Auto EOI
bit 0 = 0 8085 mode
= 1 8086/8088 mode
0021 r/w PIC master interrupt mask register
OCW1:
bit 7 = 0 enable parallel printer interrupt
bit 6 = 0 enable diskette interrupt
bit 5 = 0 enable fixed disk interrupt
bit 4 = 0 enable serial port 1 interrupt
bit 3 = 0 enable serial port 2 interrupt
bit 2 = 0 enable video interrupt
bit 1 = 0 enable keyboard, mouse, RTC interrupt
bit 0 = 0 enable timer interrupt
OCW2:
bit 7-5 = 000 rotate in auto EOI mode (clear)
= 001 nonspecific EOI
= 010 no operation
= 011 specific EOI
= 100 rotate in auto EOI mode (set)
= 101 rotate on nonspecific EOI command
= 110 set priority command
= 111 rotate on specific EOI command
bit 4 = 0 reserved
bit 3 = 0 reserved
bit 2-0 interrupt request to which the command applies
0020 r PIC interrupt request/in-service registers by OCW3
request register:
bit 7-0 = 0 no active request for the corresponding int. line
= 1 active request for corresponding interrupt line
in-service register:
bit 7-0 = 0 corresponding line not currently being serviced
= 1 corresponding int. line currently being serviced
0020 w PIC OCW3
bit 7 = 0 reserved
bit 6-5 = 0x no operation
= 10 reset special mask
= 11 set special mask
bit 4 = 0 reserved
bit 3 = 1 reserved
bit 2 = 0 no poll command
= 1 poll command
bit 1-0 = 0x no operation
= 10 read int.request register on next read at 0020
= 11 read int.in-service register on next read 0020
-------------------------------------------------------------------------------
0022-002B ---- Intel 82355, part of chipset for 386sx
initialisation in POST will disable these addresses,
only a hard reset will enable them again.
0022 r/w 82335 MCR memory configuration register
0024 82335 RC1 roll compare register
0026 82335 RC2 roll compare register
0028 82335 CC0 compare register
002A 82335 CC1 compare register
values for CC0 and CC1:
00F9,0000 enable range compare CC0 0-512K CC1 disable
00F1,0000 enable range compare CC0 0-1024K CC1 disable
00F1,10F9 enable range compare CC0 0-1M CC1 1M-1M5
00E1,0000 enable range compare CC0 0-2M CC1 disable
00E1,0000 enable range compare CC0 0-2M CC1 disable
00C1,0000 enable range compare CC0 0-4M CC1 disable
00C1,40E1 enable range compare CC0 0-4M CC1 4M-6M
0081,0000 enable range compare CC0 0-8M CC1 disable
-------------------------------------------------------------------------------
0040-005F ---- PIT (Programmable Interrupt Timer 8253, 8254)
XT & AT uses 40-43 PS/2 uses 40, 42,43,44, 47
0040 r/w PIT counter 0, counter divisor (XT, AT, PS/2)
0041 r/w PIT counter 1, RAM refresh counter (XT, AT)
0042 r/w PIT counter 2, cassette & speaker (XT, AT, PS/2)
0043 r/w PIT mode port, control word register for counters 0-2
bit 7-6 = 00 counter 0 select
= 01 counter 1 select (not PS/2)
= 10 counter 2 select
bit 5-4 = 00 counter latch command
= 01 read/write counter bits 0-7 only
= 10 read/write counter bits 8-15 only
= 11 read/write counter bits 0-7 first, then 8-15
bit 3-0 = 000 mode 0 select
= 001 mode 1 select - programmable one shot
= x10 mode 2 select - rate generator
= x11 mode 3 select - square wave generator
= 100 mode 4 select - software triggered strobe
= 101 mode 5 select - hardware triggered strobe
bit 0 = 0 binary counter 16 bits
= 1 BCD counter
0044 r/w PIT counter 3 (PS/2, EISA)
used as fail-safe timer. generates an NMI on time out.
for user generated NMI see at 0462.
0047 w PIT control word register counter 3 (PS/2, EISA)
bit 7-6 = 00 counter 3 select
= 01 reserved
= 10 reserved
= 11 reserved
bit 5-4 = 00 counter latch command counter 3
= 01 read/write counter bits 0-7 only
= 1x reserved
bit 3-0 = 00
0048 EISA
004A EISA
004B EISA
-------------------------------------------------------------------------------
0060-006F ---- Keyboard controller (8041, 8042) (or PPI (8255) on XT)
XT uses 60-63, AT uses 60-64
AT keyboard controller input port bit definitions
bit 7 = 0 keyboard inhibited
bit 6 = 0 CGA, else MDA
bit 5 = 0 manufacturing jumper installed
bit 4 = 0 system RAM 512K, else 640K
bit 3-0 reserved
AT keyboard controller output port bit definitions
bit 7 = keyboard data output
bit 6 = keyboard clock output
bit 5 = 0 input buffer full
bit 4 = 0 output buffer empty
bit 3 = reserved (see note)
bit 2 = reserved (see note)
bit 1 = gate A20
bit 0 = system reset
Note: bits 2 and 3 are the turbo speed switch or password
lock on Award/AMI/Phoenix BIOSes. These bits make
use of nonstandard keyboard controller BIOS
functionality to manipulate
pin 23 (8041 port 22) as turbo switch for AWARD
pin 35 (8041 port 15) as turbo switch/pw lock for
Phoenix
0060 r/w KB controller data port or keyboard input buffer (ISA, EISA)
should only be read from after status port bit0 = 1
should only be written to if status port bit1 = 0
keyboard commands (data goes also to port 0060):
ED dbl set/reset mode indicators Caps Num Scrl
EE sngl diagnostic echo. returns EE.
EF-F2 sngl NOP (No OPeration). reserved for future use
F3 dbl set typematic rate/delay
F4 sngl enable keyboard
F5 sngl disable keyboard. set default parameters
F6 sngl set default parameters
F7-FD sngl NOP
FE sngl resend last scancode
FF sngl perform internal power-on reset function
0060 r KeyBoard or KB controller data output buffer (via PPI on XT)
0061 w KB controller port B (ISA, EISA) (PS/2 port A is at 0092)
system control port for compatibility with 8255
bit 7 (1= IRQ 0 reset )
bit 6-4 reserved
bit 3 = 1 channel check enable
bit 2 = 1 parity check enable
bit 1 = 1 speaker data enable
bit 0 = 1 timer 2 gate to speaker enable
0061 r KB controller port B control register (ISA, EISA)
system control port for compatibility with 8255
bit 7 parity check occurred
bit 6 channel check occurred
bit 5 mirrors timer 2 output condition
bit 4 toggles with each refresh request
bit 3 channel check status
bit 2 parity check status
bit 1 speaker data status
bit 0 timer 2 gate to speaker status
0061 w PPI Programmable Peripheral Interface 8255 (XT only)
system control port
bit 7 = 1 clear keyboard
bit 6 = 0 hold keyboard clock low
bit 5 = 0 I/O check enable
bit 4 = 0 RAM parity check enable
bit 3 = 0 read low switches
bit 2 reserved, often used as turbo switch
bit 1 = 1 speaker data enable
bit 0 = 1 timer 2 gate to speaker enable
0062 r/w PPI (XT only)
bit 7 = 1 RAM parity check
bit 6 = 1 I/O channel check
bit 5 = 1 timer 2 channel out
bit 4 reserved
bit 3 = 1 system board RAM size type 1
bit 2 = 1 system board RAM size type 2
bit 1 = 1 coprocessor installed
bit 0 = 1 loop in POST
0063 r/w PPI (XT only) command mode register (read dipswitches)
bit 7-6 = 00 1 diskette drive
= 01 2 diskette drives
= 10 3 diskette drives
= 11 4 diskette drives
bit 5-4 = 00 reserved
= 01 40*25 color (mono mode)
= 10 80*25 color (mono mode)
= 11 MDA 80*25
bit 3-2 = 00 256K (using 256K chips)
= 01 512K (using 256K chips)
= 10 576K (using 256K chips)
= 11 640K (using 256K chips)
bit 3-2 = 00 64K (using 64K chips)
= 01 128K (using 64K chips)
= 10 192K (using 64K chips)
= 11 256K (using 64K chips)
bit 1-0 reserved
0064 r KB controller read status (ISA, EISA)
bit 7 = 1 parity error on transmission from keyboard
bit 6 = 1 receive timeout
bit 5 = 1 transmit timeout
bit 4 = 0 keyboard inhibit
bit 3 = 1 data in input register is command
0 data in input register is data
bit 2 = 0 system flag status 0=power up or reset 1=selftest OK
bit 1 = 1 input buffer full (input 60/64 has data for 8042)
bit 0 = 1 output buffer full (output 60 has data for system)
0064 w KB controller input buffer (ISA, EISA)
KB controller commands (data goes to port 0060):
20 read read byte zero of internal RAM, this is the
last KB command send to 8041
21-3F read reads the byte specified in the lower 5 bits of
the command in the 8041's internal RAM
60-7F dbl writes the data byte to the address specified in
the 5 lower bits of the command.
Alternate description KB IO command 60 summary:
bit7 = 0 reserved
bit6 = IBM PC compatibility mode
bit5 = IBM PC mode
bit4 = disable kb
bit3 = inhibit override
bit2 = system flag
bit1 = 0 reserved
bit0 = enableoutput buffer full interrupt
AA sngl initiate self-test. will return 55 to data port
AB sngl initiate interface test. result values:
0 = no error
1 = keyboard clock line stuck low
2 = keyboard clock line stuck high
3 = keyboard data line is stuck low
4 = keyboard data line stuck high
AC read diagnostic dump. the contents of the 8041 RAM,
output port, input port, status word are send.
AD sngl disable keyboard
AE sngl enable keyboard
AF AWARD Enhanced Command: read keyboard version
C0 read read input port
C1 AWARD Enhanced Command: poll input port Low nibble
C2 AWARD Enhanced Command: poll input port High nibble
D0 read read output port
D1 dbl write output port. next byte written to 0060
will be written to the 8041 output port
D2 AWARD Enhanced Command: write keyboard output buffer
D3 AWARD Enhanced Command: write pointing device out.buf.
D4 AWARD Enhanced Command: write to auxiliary device
DD sngl disable address line A20. default in Real Mode
DF sngl enable address line A20
E0 read read test inputs. bit0 = T0 and bit1 = T1
Exxx AWARD Enhanced Command: active output port
F0-FF sngl pulse output port low for 6 microseconds.
bits 0-3 contain the mask for the bits to be
pulsed. a bit is pulsed if it's mask bit is
zero.
0065 r communications port (Olivetti M24)
0068 w HP-Vectra control buffer (HP commands)
0069 r HP-Vectra SVC (keyboard request SerViCe port)
006A w HP-Vectra clear processing, done
006C-006F HP-HIL (Human Interface Link = async. serial inputs 0-7)
-------------------------------------------------------------------------------
0070-007F ---- CMOS RAM/RTC (Real Time Clock MC146818)
0070 w CMOS RAM index register port (ISA, EISA)
bit 7 = 1 NMI disabled
= 0 NMI enabled
bit 6-0 CMOS RAM index (64 bytes, sometimes 128 bytes)
any write to 0070 should be followed by an action to 0071
or the RTC wil be left in an unknown state.
0071 r/w CMOS RAM data port (ISA, EISA)
RTC registers:
00 current second in BCD
01 alarm second in BCD
02 current minute in BCD
03 alarm minute in BCD
04 current hour in BCD
05 alarm hour in BCD
06 day of week in BCD
07 day of month in BCD
08 month in BCD
09 year in BCD (00-99)
0A status register A
bit 7 = 1 update in progress
bit 6-4 divider that identifies the time-based
frequency
bit 3-0 rate selection output frequency and int. rate
0B status register B
bit 7 = 0 run
= 1 halt
bit 6 = 1 enable periodic interrupt
bit 5 = 1 enable alarm interrupt
bit 4 = 1 enable update-ended interrupt
bit 3 = 1 enable square wave interrupt
bit 2 = 1 calendar is in binary format
= 0 calendar is in BCD format
bit 1 = 1 24-hour mode
= 0 12-hour mode
bit 0 = 1 enable daylight savings time. only in USA.
useless in Europe. Some DOS versions clear
this bit when you use the DAT/TIME command.
0C status register C
bit 7 = interrupt request flag
bit 6 = peridoc interrupt flag
bit 5 = alarm interrupt flag
bit 4 = update interrupt flag
bit 3-0 reserved
0D status register D
bit 7 = 1 Real-Time Clock has power
bit 6-0 reserved
0E diagnostics status byte
bit 7 = 0 RTC lost power
bit 6 = 1 CMOS RAM checksum bad
bit 5 = 1 invalid configuration information at POST
bit 4 = 1 memory size error at POST
bit 3 = 1 fixed disk/adapter failed initialization
bit 2 = 1 CMOS RAM time found invalid
bit 1 = 1 adapters do not match configuration (EISA)
bit 0 = 1 time out reading an adapter ID (EISA)
0F shutdown status byte
00 = normal execution of POST
01 = chip set initialization for real mode reentry
04 = jump to bootstrap code
05 = issue an EOI an JMP to Dword ptr at 40:67
06 = JMP to Dword ptrv at 40:67 without EOI
07 = return to INT15/87 (block move)
08 = return to POST memory test
09 = return to INT15/87 (block move)
0A = JMP to Dword ptr at 40:67 without EOI
0B = return IRETS through 40:67
10 diskette drive type for A: and B:
bit 7-4 drive type of drive 0
bit 3-0 drive type of drive 1
= 0000 no drive
= 0001 360K
= 0010 1M2
= 0011 720K
= 0100 1M44
= 0101-1111 reserved
11 reserved / AMI Extended CMOS setup (AMI Hi-Flex BIOS)
bit 7 = 1 Typematic Rate Programming
bit 6-5 = 00 Typematic Rate Delay 250 mSec
bit 4-0 = 00011 Typematic Rate 21.8 Chars/Sec
12 fixed disk drive type for drive 0 and drive 1
bit 7-4 drive type of drive 0
bit 3-0 drive type of drive 1
if either of the nibbles equals 0F, then bytes
19 an 1A are valid
13 reserved / AMI Extended CMOS setup (AMI Hi-Flex BIOS)
bit 7 = 1 Mouse Support Option
bit 6 = 1 Above 1 MB Memory Test disable
bit 5 = 1 Memory Test Tick Sound disable
bit 4 = 1 Memory Parity Error Check enable
bit 3 = 1 Hit <ESC> Message Display disabled
bit 2 = 1 Hard Disk Type 47 Data Area at address 0:300
bit 1 = 1 Wait For <F1> If Any Error enabled
bit 0 = 1 System Boot Up Num Lock is On
14 equipment byte
bit 7-6 diskette drives installed
= 00 1 drive installed
= 01 2 drives installed
= 10 reserved
= 11 reserved
bit 5-4 primary display
= 00 adapter card with option ROM
= 01 40*25 color
= 10 80*25 color
= 11 monochrome
bit 3-2 reserved
bit 1 = 1 coprocessor installed (non-Weitek)
bit 0 diskette drive avaliable for boot
15 LSB of systemn base memory in Kb
16 MSB of systemn base memory in Kb
17 LSB of total extended memory in Kb
18 MSB of total extended memory in Kb
19 drive C extension byte
1A drive D extension byte
1B-27 reserved
1B/1C word to 82335 RC1 roll compare register at [24]
(Phoenix)
1D/1E word to 82335 RC2 roll compare register at [26]
(Phoenix)
28 HP-Vectra checksum over 29-2D
29-2D reserved
29/2A word to Intel 82335 CC0 compare register at
[28](Phoenix)
2B/2C word send to 82335 CC1 compare register at [2A]
(Phoenix)
2D AMI Extended CMOS setup (AMI Hi-Flex BIOS)
(Phoenix BIOS checks for the values AA or CC)
bit 7 = 1 Weitek Processor Absent
bit 6 = 1 Floppy Drive Seek At Boot disabled
bit 5 = 1 System Boot Up Sequence C:, A:
bit 4 = 1 System Boot Up Speed is high
bit 3 = 1 Cache Memory enabled
bit 2 = 1 Internal Cache Memory <1>
bit 1-0 reserved
2E CMOS MSB checksum over 10-2D
2F CMOS LSB checksum over 10-2D
30 LSB of extended memory found above 1Mb at POST
31 MSB of extended memory found above 1Mb at POST
32 date century in BCD
33 information flags
bit4 = bit4 from CPU register CR0 (Phoenix)
this bit is only known as INTEL RESERVED
34-3F reserved
34 bit4 bit5 (Phoenix BIOS)
3D/3E word to 82335 MCR memory config register at
[22](Phoenix)
3D bit3 base memsize 512/640 (Phoenix)
3E bit7 = 1 relocate enable (Phoenix)
bit1 = 1 shadow video enable (Phoenix)
bit0 = 1 shadow BIOS enable (Phoenix)
User Definable Drive Parameters are also stored in CMOS RAM:
AMI (386sx BIOS 1989) first user definable drive (type 47)
1B L cylinders
1C H cylinders
1D heads
1E L Write Precompensation Cylinder
1F H Write Precompensation Cylinder
20 ??
21 L cylinders parking zone
22 H cylinders parking zone
23 sectors
AMI (386sx BIOS 1989) second user definable drive (type 48)
24 L cylinders
25 H cylinders
26 heads
27 L Write Precompensation Cylinder
28 H Write Precompensation Cylinder
29 ??
2A L cylinders parking zone
2B H cylinders parking zone
2C sectors
Phoenix (386BIOS v1.10.03 1988) 1st user definable drv (type48)
20 L cylinders
21 H cylinders
22 heads
23 L Write Precompensation Cylinder
24 H Write Precompensation Cylinder
25 L cylinders parking zone
26 H cylinders parking zone
27 sectors
Phoenix (386BIOS v1.10.03 1988) 2nd user definable drv (type49)
(when PS/2-style password option is not used)
35 L cylinders
36 H cylinders
37 heads
38 L Write Precompensation Cylinder
39 H Write Precompensation Cylinder
3A L cylinders parking zone
3B H cylinders parking zone
3C sectors
0078 HP-Vectra Hard Reset: NMI enable/disable
bit 7 = 0 disable & clear hard reset from HP-HIL controller
= 1 enable hard reset from HP-HIL controller chip
bit 6-0 reserved
-------------------------------------------------------------------------------
007C-007D ---- HP-Vectra PIC 3 (Programmable Interrupt Controller 8259)
cascaded to first controller.
used for keyboard and input device interface.
007C r/w HP-Vectra PIC 3 see at 0020 PIC 1
007D r/w HP-Vectra PIC 3 see at 0021 PIC 1
-------------------------------------------------------------------------------
0080 w Manufacturing Diagnostics port
-------------------------------------------------------------------------------
0080-008F ---- DMA page registers (74612)
0080 r/w extra page register (temporary storage)
0081 r/w DMA channel 2 address byte 2
0082 r/w DMA channel 3 address byte 2
0083 r/w DMA channel 1 address byte 2
0084 r/w extra page register
0085 r/w extra page register
0086 r/w extra page register
0087 r/w DMA channel 0 address byte 2
0088 r/w extra page register
0089 r/w DMA channel 6 address byte 2
0089 r/w DMA channel 7 address byte 2
0089 r/w DMA channel 5 address byte 2
008C r/w extra page register
008D r/w extra page register
008E r/w extra page register
008F r/w DMA refresh page register
-------------------------------------------------------------------------------
0090-009F ---- PS/2 POS (Programmable Option Select)
0090 Central arbitration control port
0091 Card selection feedback
0092 r/w PS/2 system control port A (port B is at 0061)
bit 7-6 any bit set to 1 turns activity light on
bit 5 reserved
bit 4 = 1 watchdog timout occurred
bit 3 = 0 RTC/CMOS security lock (on password area) unlocked
= 1 CMOS locked (done by POST)
bit 2 reserved
bit 1 = 1 indicates A20 active
bit 0 = 0 system reset or write
1 pulse alternate reset pin (alternate CPU reset)
0094 w system board enable/setup register
bit 7 = 1 enable functions
= 0 setup functions
bit 5 = 1 enables VGA
= 0 setup VGA
0095 reserved
0096 w adapter enable /setup register
bit 3 = 1 setup adapters
= 0 enable registers
0097 reserved
-------------------------------------------------------------------------------
00A0-00AF ---- PIC 2 (Programmable Interrupt Controller 8259)
00A0 r/w NMI mask register (XT)
00A0 r/w PIC 2 same as 0020 for PIC 1
00A1 r/w PIC 2 same as 0021 for PIC 1 except for OCW1:
bit 7 = 0 reserved
bit 6 = 0 enable fixed disk interrupt
bit 5 = 0 enable coprocessor exception interrupt
bit 4 = 0 enable mouse interrupt
bit 3 = 0 reserved
bit 2 = 0 reserved
bit 1 = 0 enable redirect cascade
bit 0 = 0 enable real-time clock interrupt
-------------------------------------------------------------------------------
00C0 ---- TI SN746496 programmable tone/noise generator PCjr
-------------------------------------------------------------------------------
00C0-00DF ---- DMA 2 (second Direct Memory Access controller 8237)
00C0 r/w DMA channel 4 memory address bytes 1 and 0 (low) (ISA, EISA)
00C2 r/w DMA channel 4 transfer count bytes 1 and 0 (low) (ISA, EISA)
00C4 r/w DMA channel 5 memory address bytes 1 and 0 (low) (ISA, EISA)
00C6 r/w DMA channel 5 transfer count bytes 1 and 0 (low) (ISA, EISA)
00C8 r/w DMA channel 6 memory address bytes 1 and 0 (low) (ISA, EISA)
00CA r/w DMA channel 6 transfer count bytes 1 and 0 (low) (ISA, EISA)
00CC r/w DMA channel 7 memory address byte 0 (low), then 1 (ISA, EISA)
00CE r/w DMA channel 7 transfer count byte 0 (low), then 1 (ISA, EISA)
00D0 r DMA channel 4-7 status register (ISA, EISA)
bit 7 = 1 channel 7 request
bit 6 = 1 channel 6 request
bit 5 = 1 channel 5 request
bit 4 = 1 channel 4 request
bit 3 = 1 terminal count on channel 7
bit 2 = 1 terminal count on channel 6
bit 1 = 1 terminal count on channel 5
bit 0 = 1 terminal count on channel 4
00D0 w DMA channel 4-7 command register (ISA, EISA)
bit 7 = 1 DACK sense active high
= 0 DACK sense active low
bit 6 = 1 DREQ sense active high
= 0 DREQ sense active low
bit 5 = 1 extended write selection
= 0 late write selection
bit 4 = 1 rotating priority
= 0 fixed priority
bit 3 = 1 compressed timing
= 0 normal timing
bit 2 = 0 enable controller
bit 1 = 1 enable memory-to-memory transfer
bit 0 .....
00D2 w DMA channel 4-7 write request register (ISA, EISA)
00D4 w DMA channel 4-7 write single mask register (ISA, EISA)
bit 7-3 reserved
bit 2 = 0 clear mask bit
= 1 set mask bit
bit 1-0 = 00 channel 4 select
= 01 channel 5 select
= 10 channel 6 select
= 11 channel 7 select
00D6 w DMA channel 4-7 mode register (ISA, EISA)
bit 7-6 = 00 demand mode
= 01 single mode
= 10 block mode
= 11 cascade mode
bit 5 = 0 address increment select
= 1 address decrement select
bit 4 = 0 autoinitialisation disable
= 1 autoinitialisation enable
bit 3-2 = 00 verify operation
= 01 write to memory
= 10 read from memory
= 11 reserved
bit 1-0 = 00 channel 4 select
= 01 channel 5 select
= 10 channel 6 select
= 11 channel 7 select
00D8 w DMA channel 4-7 clear byte pointer flip-flop (ISA, EISA)
00DA r DMA channel 4-7 read temporary register (ISA, EISA)
00DA w DMA channel 4-7 master clear (ISA, EISA)
00DC w DMA channel 4-7 clear mask register (ISA, EISA)
00DE w DMA channel 4-7 write mask register (ISA, EISA)
00E0 split address register, memory encoding registers PS/2m80 only
-------------------------------------------------------------------------------
00F0-00F5 ---- PCjr Disk Controller
00F0 disk controller
00F2 disk controller control port
00F4 disk controller status register
00F5 disk controller data port
-------------------------------------------------------------------------------
00F0-00FF ---- coprocessor (8087..80387)
00F0 math coprocessor clear busy latch
00F1 math coprocessor reset
00F8-00FF math coprocessor
-------------------------------------------------------------------------------
0100-0107 ---- PS/2 POS (Programmable Option Select)
0100 r POS register 0 Low adapter ID byte
0101 r POS register 1 High adapter ID byte
0102 r/w POS register 2 option select data byte 1
bit 0 is card enable (CDEN)
0103 r/w POS register 3 option select data byte 2
0104 r/w POS register 4 option select data byte 3
0105 r/w POS register 5 option select data byte 4
bit 7 channel active (-CHCK)
bit 6 channel status
0106 r/w POS register 6 Low subaddress extension
0107 r/w POS register 7 High subaddress extension
-------------------------------------------------------------------------------
0140-014F ---- SCSI (alternate Small Computer System Interface) adapter
(1st at 0340-034F)
-------------------------------------------------------------------------------
0140-0157 ---- RTC (alternate Real Time Clock for XT) (1st at 0340-0357)
-------------------------------------------------------------------------------
0170-0177 ---- HDC 2 (2nd Fixed Disk Controller) same as 01Fx (ISA, EISA)
-------------------------------------------------------------------------------
01F0-01F7 ---- HDC 1 (1st Fixed Disk Controller) same as 017x (ISA, EISA)
01F0 r/w data register
01F1 r error register
diagnostic mode errors:
bit 7-3 reserved
bit 2-1 = 001 no error detected
= 010 formatter device error
= 011 sector buffer error
= 100 ECC circuitry error
= 101 controlling microprocessor error
operation mode:
bit 7 = 1 bad block detected
= 0 block OK
bit 6 = 1 uncorrectable ECC error
= 0 no error
bit 5 reserved
bit 4 = 1 ID found
= 0 ID not found
bit 3 reserved
bit 2 = 1 command completed
= 0 command aborted
bit 1 = 1 track 000 not found
= 0 track 000 found
bit 0 = 1 DAM not found
= 0 DAM found (CP-3022 always 0)
01F1 w WPC/4 (Write Precompensation Cylinder divided by 4)
01F2 r/w sector count
01F3 r/w sector number
01F4 r/w cylinder low
01F5 r/w cylinder high
01F6 r/w drive/head
bit 7 = 1
bit 6 = 0
bit 5 = 1
bit 4 = 0 drive 0 select
= 1 drive 1 select
bit 3-0 head select bits
01F7 r status register
bit 7 = 1 controller is executing a command
bit 6 = 1 drive is ready
bit 5 = 1 write fault
bit 4 = 1 seek complete
bit 3 = 1 sector buffer requires servicing
bit 2 = 1 disk data read successfully corrected
bit 1 = 1 index - set to 1 each disk revolution
bit 0 = 1 previous command ended in an error
01F7 w command register
commands:
98 E5 check power mode (IDE)
90 execute drive diagnostics
50 format track
EC identify drive (IDE)
97 E3 idle (IDE)
95 E1 idle immediatete (IDE)
91 initialize drive parameters
1x recalibrate
E4 read buffer (IDE)
C8 read DMA with retry (IDE)
C9 read DMA without retry (IDE)
C4 read multiplec (IDE)
20 read sectors with retry
21 read sectors without retry
22 read long with retry
23 read long without retry
40 read verify sectors with retry
41 read verify sectors without retry
7x seek
EF set features (IDE)
C6 set multiple mode (IDE)
99 E6 set sleep mode (IDE)
96 E2 standby (IDE)
94 E0 standby immediate (IDE)
E8 write buffer (IDE)
CA write DMA with retry (IDE)
CB write DMA with retry (IDE)
C5 write multiple (IDE)
E9 write same (IDE)
30 write sectors with retry
31 write sectors without retry
32 write long with retry
33 write long without retry
3C write verify (IDE)
9A vendor unique (IDE)
C0-C3 vendor unique (IDE)
8x vendor unique (IDE)
F0-F4 EATA standard (IDE)
F5-FF vendor unique (IDE)
-------------------------------------------------------------------------------
0200-020F ---- Game port reserved I/O address space
0200-0207 ---- Game port, eight identical addresses on some boards
0201 r read joystick position and status
bit 7 status B joystick button 2 / D paddle button
bit 6 status B joystick button 1 / C paddle button
bit 5 status A joystick button 2 / B paddle button
bit 4 status A joystick button 1 / A paddle button
bit 3 B joystick Y coordinate / D paddle coordinate
bit 2 B joystick X coordinate / C paddle coordinate
bit 1 A joystick Y coordinate / B paddle coordinate
bit 0 A joystick X coordinate / A paddle coordinate
w fire joysticks four one-shots
-------------------------------------------------------------------------------
0210-0217 ---- Expansion unit (XT)
0210 w latch expansion bus data
r verify expansion bus data
0211 w clear wait, test latch
r High byte data address
0212 r Low byte data address
0213 w 0=enable, 1=disable expansion unit
0214 w latch data (receiver card port)
r read data (receiver card port)
0215 r High byte of address, then Low byte (receiver card port)
-------------------------------------------------------------------------------
0240-0257 ---- RTC (alternate Real Time Clock for XT) (1st at 0340-0357)
(used by TIMER.COM v1.2 which is the 'standard' timer program)
-------------------------------------------------------------------------------
0258-025F ---- Intel Above Board
-------------------------------------------------------------------------------
0278-027E ---- parallel printer port, same as 0378 and 03BC
0278 w data port
0279 r/w status port
027A r/w control port
-------------------------------------------------------------------------------
02A2-02A3 ---- MSM58321RS clock
-------------------------------------------------------------------------------
02B0-02DF ---- alternate EGA, primary EGA at 03C0
-------------------------------------------------------------------------------
02C0-02Cx ---- AST-clock
-------------------------------------------------------------------------------
02E0-02EF ---- GPIB (General Purpose Interface Bus, IEEE 488 interface)
(GAB 0 on XT)
02E1 GPIB (adapter 0)
02E2
02E3
-------------------------------------------------------------------------------
02E0-02EF ---- data aquisition (AT)
02E2 data aquisition (adapter 0)
02E3 data aquisition (adapter 0)
-------------------------------------------------------------------------------
02E8-02EF ---- serial port, same as 02F8
-------------------------------------------------------------------------------
02F8-02FF ---- serial port, same as 0378 and 03F8
02F8 w transmitter holding register
02F8 r receiver buffer register
r/w divisor latch, low byte when DLAB=1
02F9 r/w divisor latch, high byte when DLAB=1
r/w interrupt enable register when DLAB=0
02FA r interrupt identification register
02FB r/w line control register
02FC r/w modem control register
02FD r line status register
02FF r/w scratch register
-------------------------------------------------------------------------------
0300-031F ---- prototype cards
Periscope hardware debugger
-------------------------------------------------------------------------------
0300-030F ---- Philips CR-ROM player CM50
0310-031F ---- Philips CR-ROM player CM50
-------------------------------------------------------------------------------
0320-0323 ---- XT HDC 1 (Hard Disk Controller)
0320 r/w data register
0321 w reset controller
r read controller hardware status
bit 7-6 = 0
bit 5 logical unit number
bit 4-2 = 0
bit 1 = 0 no error
bit 0 = 0
0322 r read DIPswitch setting on XT controller card
w generate controller-select pulse
0323 w write pattern to DMA and INT mask register
0324-0327 ---- XT HDC 2 (Hard Disk Controller)
0328-032B ---- XT HDC 3 (Hard Disk Controller)
032C-032F ---- XT HDC 4 (Hard Disk Controller)
-------------------------------------------------------------------------------
0330-0331 ---- MIDI interface
-------------------------------------------------------------------------------
0338 ---- AdLib soundblaster card
-------------------------------------------------------------------------------
0330-033F ---- Philips CR-ROM player CM50
0340-034F ---- Philips CR-ROM player CM50
-------------------------------------------------------------------------------
0340-034F ---- SCSI (1st Small Computer System Interface) adapter
(alternate at 0140-014F)
-------------------------------------------------------------------------------
0340-0357 ---- RTC (1st Real Time Clock for XT), (alternate at 0240-0257)
(used by TIMER.COM v1.2 which is the 'standard' timer program)
0340 r/w 0.01 seconds 0-99
0341 r/w 0.1 seconds 0-99
0342 r/w seconds 0-59
0343 r/w minutes 0-59
0343 r/w hours 0-23
0345 r/w day of week 1-7
0346 r/w day of month 1-31
0347 r/w month 1-12
0348
0349 r/w year 0-99
034A
034B
034C
034D
034E
034F
0350 r status?
0351
0352
0353
0354 r status?
0355
0356
0357
-------------------------------------------------------------------------------
0348-0357 ---- DCA 3278
-------------------------------------------------------------------------------
0360-036F ---- PC network (AT)
0360-0367 ---- PC network (XT only)
-------------------------------------------------------------------------------
0370-0377 ---- FDC 2 (2nd Floppy Disk Controller 8272) same as 03F0
0372 w diskette controller DOR (Digital Output Register)
0374 r diskette controller status register
0375 r/w diskette controller data register
0376 r/w FIXED disk controller data register
0377 r diskette controller DIR (Digital Input Register)
0377 w select register for diskette data transfer rate
-------------------------------------------------------------------------------
0378-037A ---- parallel printer port, same as 0278 and 03BC
0378 w data port
0379 r/w status port
037A r/w control port
-------------------------------------------------------------------------------
0380-038F ---- 2nd Binary Synchronous Data Link Control adapter (see 03A0)
0380 r/w on board 8255 port A, internal/external sense
0381 r/w on board 8255 port B, external modem interface
0382 r/w on board 8255 port C, internal control and gating
0383 r/w on board 8255 mode register
0384 r/w on board 8253 channel square wave generator
0385 r/w on board 8253 channel 1 inactivity time-out
0386 r/w on board 8253 channel 2 inactivity time-out
0387 r/w on board 8253 mode register
0388 r/w on board 8273 read: status write: command
0389 r/w on board 8273 read: response write: parameter
038A r/w on board 8273 transmit interrupt status
038B r/w on board 8273 receiver interrupt status
038C r/w on board 8273 data
-------------------------------------------------------------------------------
0390-039F ---- Cluster adapter (AT)
0390-0393 (adapter 0) (XT)
-------------------------------------------------------------------------------
03A0-03AF ---- 1st SDLC (Binary Synchronous Data Link Control adapter)
0380 r/w on board 8255 port A, internal/external sense
0381 r/w on board 8255 port B, external modem interface
0382 r/w on board 8255 port C, internal control and gating
0383 r/w on board 8255 mode register
0384 r/w on board 8253 counter 0 unused
0385 r/w on board 8253 channel 1 inactivity time-out
0386 r/w on board 8253 channel 2 inactivity time-out
0387 r/w on board 8253 mode register
0388 r/w on board 8251 data
0389 r/w on board 8251 command/mode/status register
-------------------------------------------------------------------------------
03B0-03BF ---- MDA (Monochrome Display Adapter based on 6845)
03B0 same as 03B4
03B1 same as 03B5
03B2 same as 03B4
03B3 same as 03B5
03B4 w MDA CRT index register (EGA/VGA)
selects which register (0-11h) is to be accessed through 3B5
03B5 r/w MDA CRT data register (EGA/VGA)
selected by port 3B4. registers C-F may be read
00 horizontal total
01 horizontal displayed
02 horizontal sync position
03 horizontal sync pulse width
04 vertical total
05 vertical displayed
06 vertical sync position
07 vertical sunc pulse width
08 interlace mode
09 maximum scan lines
0A cursor start
0B cursor end
0C start address high
0D start address low
0E cursor location high
0F cursor location low
10 light pen high
11 light pen low
03B6 same as 03B4
03B7 same as 03B5
03B8 r/w MDA mode control register
bit 7 not used
bit 6 not used
bit 5 enable blink
bit 4 not used
bit 3 video enable
bit 2 not used
bit 1 not used
bit 0 high resolution mode
03B9 reserved for color select register on color adapter
03BA r CRT status register EGA/VGA: input status 1 register
bit 7-4 reserved
bit 3 black/white video
bit 2-1 reserved
bit 0 horizontal drive
03BA w EGA/VGA feature control register
03BB reserved for light pen strobe reset
-------------------------------------------------------------------------------
03BC-03BF ---- parallel printer port, same as 0278 and 0378
03BC w data port
03BD r/w status port
bit 7 = 0 busy
bit 6 = 0 acknowledge
bit 5 = 1 out of paper
bit 4 = 1 printer is selected
bit 3 = 0 error
bit 2 = 0 IRQ has occurred
bit 1-0 reserved
03BE r/w control port
bit 7-5 reserved
bit 4 = 1 enable IRQ
bit 3 = 1 select printer
bit 2 = 0 initialize printer
bit 1 = 1 automatic line feed
bit 0 = 1 strobe
-------------------------------------------------------------------------------
03BF r/w Hercules configuration switch register
bit 7-2
bit 1 = 0 disables upper 32K of graphics mode buffer
1 enables upper 32K of graphics mode buffer
bit 0 = 0 prevents graphics mode
1 allows graphics mode
-------------------------------------------------------------------------------
03C0-03CF ---- EGA (1st Enhanced Graphics Adapter) alternate at 02C0
03C0 (r)/w EGA VGA ATC index/data register
03C1 r VGA other attribute register
03C2 r EGA VGA input status 0 register
w VGA miscellaneous output register
03C3 r/w VGA video subsystem enable
03C4 w EGA TS index register
r/w VGA sequencer index register
03C5 w EGA TS data register
r/w VGA other sequencer register
03C6 r/w VGA PEL mask register
03C7 r/w VGA PEL address read mode
r VGA DAC state register
03C8 r/w VGA PEL address write mode
03C9 r/w VGA PEL data register
03CA w EGA graphics 2 position register
r VGA feature control register
03CC w EGA graphics 1 position register
r VGA miscellaneous output register
03CE w EGA GDC index register
r/w VGA graphics address register
03CF w EGA GDC data register
r/w VGA other graphics register
-------------------------------------------------------------------------------
03D0-03DF ---- CGA (Color Graphics Adapter)
03D0 same as 03D4
03D1 same as 03D5
03D2 same as 03D4
03D3 same as 03D5
03D4 w CRT (6845) index register (EGA/VGA)
selects which register (0-11h) is to be accessed through 3B5
03D5 w CRT (6845) data register (EGA/VGA)
selected by port 3B4. registers C-F may be read
(for registers see at 3B5)
03D6 same as 03D4
03D7 same as 03D5
03D8 r/w CGA mode control register (except PCjr)
bit 7-6 not used
bit 5 = 1 blink enabled
bit 4 = 1 640*200 graphics mode
bit 3 = 1 video enabled
bit 2 = 1 monochrome signal
bit 1 = 0 text mode
= 1 320*200 graphics mode
bit 0 = 0 40*25 text mode
= 1 80*25 text mode
03D9 r/w CGA palette register
bit 7-6 not used
bit 5 = 0 active color set: red, green brown
= 1 active color set: cyan, magenta, white
bit 4 intense colors in graphics, background colors text
bit 3 intense border in 40*25, intense background
320*200
intense foreground in 640*200
bit 2 red border in 40*25, red background in 320*200,
red foreground in 640*200
bit 1 green border in 40*25, green background in
320*200,
green foreground in 640*200
bit 0 blue border in 40*25, blue background in 320*200,
blue foreground in 640*200
03DA r CGA status register EGA/VGA: input status 1 register
bit 7-4 not used
bit 3 = 1 in vertical retrace
bit 2 = 1 light pen switch is off
bit 1 = 1 positive edge from light pen has set trigger
bit 0 = 0 do not use memory
= 1 memory access without interfering with display
03DA w EGA/VGA feature control register
03DB w clear light pen latch
03DC r/w preset licht pen latch
03DF CRT/CPU page register PCjr only
-------------------------------------------------------------------------------
03E8-03EF ---- serial port, same as 03F8
-------------------------------------------------------------------------------
03F0-03F7 ---- FDC 1 (1st Floppy Disk Controller 8272) same as 0370
03F0 diskette controller status A (PS/2)
bit 7 interrupt pending
bit 6 second drive installed
bit 5 step
bit 4 track 0
bit 3 head 1 select
bit 2 index
bit 1 write protect
bit 0 direction
03F1 r diskette controller status B (PS/2)
bit 7-6 reserved
bit 5 drive select
bit 4 write data
bit 3 read data
bit 2 write enable
bit 1 motor enable 1
bit 0 motor enable 0
floppy drive select (0=A 1=B .. )
03F2 w diskette controller DOR (Digital Output Register)
bit 7-6 reserved PS/2
bit 7 = 1 drive 3 motor enable
bit 6 = 1 drive 2 motor enable
bit 5 = 1 drive 1 motor enable
bit 4 = 1 drive 0 motor enable
bit 3 = 1 diskette DMA enable (reserved PS/2)
bit 2 = 1 FDC enable (controller reset)
= 0 hold FDC at reset
bit 1-0 drive select (0=A 1=B ..)
03F4 r diskette controller status register
bit 7 = 1 data register is ready
bit 6 = 1 transfer is from controller to system
0 transfer is from system to controller
bit 5 = 1 non-DMA mode
bit 4 = 1 diskette controller busy
bit 3 = 1 drive 3 busy (reserved on PS/2)
bit 2 = 1 drive 2 busy (reserved on PS/2)
bit 1 = 1 drive 1 busy
bit 0 = 1 drive 0 busy
03F5 r diskette command status register 0
bit 7-6 last command status
= 00 command terminated successfully
= 01 command terminated abnormally
= 10 invalid command
= 11 terminated abnormally by change in ready signal
bit 5 = 1 seek completed
bit 4 = 1 equipment check occurred after error
bit 3 = 1 not ready
bit 2 = 1 head number at interrupt
bit 1-0 = 1 unit select (0=A 1=B .. )
(on PS/2 01=A 10=B)
status register 1
bit 7 end of cylinder; sector# greater then sectors/track
bit 6 = 0
bit 5 = 1 CRC error in ID or data field
bit 4 = 1 overrun
bit 3 = 0
bit 2 = 1 sector ID not found
bit 1 = 1 write protect detected during write
bit 0 = 1 ID address mark not found
status register 2
bit 7 = 0
bit 6 = 1 deleted Data Eddress Mark detected
bit 5 = 1 CRC error in data
bit 4 = 1 wrong cylinder detected
bit 3 = 1 scan command equal condition satisfied
bit 2 = 1 scan command failed, sector not found
bit 1 = 1 bad cylinder, ID not found
bit 0 = 1 missing Data Address Mark
status register 3
bit 7 fault status signal
bit 6 write protect status
bit 5 ready status
bit 4 track zero status
bit 3 two sided status signal
bit 2 side select (head select)
bit 1-0 unit select (0=A 1=B .. )
03F6 r/w FIXED disk controller data register
bit 7-4 reserved
bit 3 = 0 reduce write current
1 head select 3 enable
bit 2 = 1 disk reset enable
0 disk reset disable
bit 1 = 0 disk initialization enable
1 disk initialization disable
bit 0 reserved
03F7 r diskette controller DIR (Digital Input Register)
bit 7 = 1 diskette change
bit 6 FIXED DISK write gate
bit 5 FIXED DISK head select 3 / reduced write current
bit 4 FIXED DISK head select 2
bit 3 FIXED DISK head select 1
bit 2 FIXED DISK head select 0
bit 1 FIXED DISK drive 1 select
bit 0 FIXED DISK drive 0 select conflicts with:
bit 0 diskette high density select
03F7 w select register for diskette data transfer rate
bit 7-2 reserved
bit 1-0 = 00 500 Kb/S mode
= 01 300 Kb/S mode
= 10 250 Kb/S mode
= 11 reserved
-------------------------------------------------------------------------------
03F8-03FF ---- serial port (8250, 8251, 16450, 16550), same as 02F8 and 0378
03F8 w serial port, transmitter holding register, which contains the
character to be sent. Bit 0 is sent first.
bit 7-0 data bits when DLAB=0 (Divisor Latch Access Bit)
r receiver buffer register, which contains the received character
Bit 0 is received first
bit 7-0 data bits when DLAB=0 (Divisor Latch Access Bit)
r/w divisor latch low byte when DLAB=1
03F9 r/w divisor latch high byte when DLAB=1
r/w interrupt enable register when DLAB=0
bits 7-4 reserved
bit 3 = 1 modem-status interrupt enable
bit 2 = 1 receiver-line-status interrupt enable
bit 1 = 1 transmitter-holding-register empty interrupt enable
bit 0 = 1 received-data-avail.int. enable (and 16550 timeout)
- 16550 will interrupt if data axists in the FIFO and isn't read
within the time it takes to receive four bytes or if no data is
received within the time it takes to receive four bytes
03FA r interrupt identification register. Information about a pending
interrupt is stored here. When the ID register is addressed,
the highest priority interrupt is held, and no other interrupts
are acknowledged until the CPU services that interrupt.
bit 7-6 = 00 reserved on 8250, 8251, 16450
= 11 if FIFO queues are enabled (16550 only)
bit 5-4 = 0 reserved
bit 3 = 0 reserved 8250, 16450
= 1 16550 timeout int. pending
bit 2-1 identify pending interrupt with the highest priority
= 11 receiver line status interrupt. priority=highest
= 10 received data available register interrupt. pr.=second
= 01 transmitter holding register empty interrupt. pr.=third
= 00 modem status interrupt. priority=fourth
bit 0 = 0 interrupt pending. contents of register can be used
as a pointer to the appropriate int.service routine
1 no interrupt pending
- interrupt pending flag uses reverse logic, 0=pending, 1=none
- interrupt will occur if any of the line status bits are set
- THRE bit is set when THRE register is emptied into the TSR
03FA w 16650 FCR (FIFO Control Register)
bit 7-6 = 00 1 byte
= 01 4 bytes
= 10 8 bytes
= 11 14 bytes
bit 5-4 = 00 reserved
bit 3 = 1 change RXRDY TXRDY pins from mode 0 to mode 1
bit 2 = 1 clear XMIT FIFO
bit 1 = 1 clear RCVR FIFO
bit 0 = 1 enable clear XMIT and RCVR FIFO queues
- bit 0 must be set in ordewr to write to other FCR bits
- bit 1 when set the RCVR FIFO is cleared and this bit is reset
the receiver shift register is not cleared
- bit 2 when set the XMIT FIFO is cleared and this bit is reset
the transmit shift register is not cleared
03FB r/w line control register
bit 7 = 1 divisor latch access bit (DLAB)
0 receiver buffer, transmitter holding, or interrupt
enable register access
bit 6 = 1 set break enable. serial ouput is forced to spacing
state and remains there.
bit 5 = stick parity
bit 4 = 1 even parity select
bit 3 = parity enable
1 even number of ones are sent and checked in the
data word bits and parity bit
0 odd number of ones are sent and checked
bit 2 = 0 one stop bit
1 zero stop bit
bit 1-0 00 word length is 5 bits
01 word length is 6 bits
10 word length is 7 bits
11 word length is 8 bits
03FC r/w modem control register
bit 7-5 = 0 reserved
bit 4 = 1 loopback mode for diagnostic testing of serial port
output of transmitter shift register is looped back
to receiver shift register input. In this mode
transmitted data is received immediately so that
the CPU can verify the transmit data/receive data
serial port paths.
bit 3 = 1 auxiliary user-designated output 2
bit 2 = 1 auxiliary user-designated output 1
bit 1 = 1 force request-to-send active
bit 0 = 1 force data-terminal-ready active
03FD r line status register
bit 7 = 0 reserved
bit 6 = 1 transmitter shift and holding registers empty
bit 5 = 1 transmitter holding register empty. Controller is
ready toaccept a new character to send.
bit 4 = 1 break interrupt. the received data input is held in
in the zero bit state longer than the time of start
bit + data bits + parity bit + stop bits.
bit 3 = 1 framing error. the stop bit that follows the last
parity or data bit is a zero bit.
bit 2 = 1 parity error. Character has wrong parity
bit 1 = 1 overrun error. a character was sent to the receiver
buffer before the previous character in the buffer
could be read. This destroys the previous
character.
bit 0 = 1 data ready. a complete incoming character has been
received and sent to the receiver buffer register.
03FE r modem status register
bit 7 = 1 data carrier detect
bit 6 = 1 ring indicator
bit 5 = 1 data set ready
bit 4 = 1 clear to send
bit 3 = 1 delta data carrier detect
bit 2 = 1 trailing edge ring indicator
bit 1 = 1 delta data set ready
bit 0 = 1 delta clear to send
- bits 0-3 are reset when the CPU reads the MSR
- bit 4 is the Modem Control Register RTS during loopback test
- bit 5 is the Modem Control Register DTR during loopback test
- bit 6 is the Modem Control Register OUT1 during loopback test
- bit 7 is the Modem Control Register OUT2 during loopback test
03FF r/w scratch register
-------------------------------------------------------------------------------
Adresses above 03FF apply to EISA machines only !
1000-1FFF slot 1 EISA
2000-2FFF slot 2 EISA
3000-3FFF slot 3 EISA
4000-4FFF slot 4 EISA
5000-5FFF slot 5 EISA
6000-6FFF slot 6 EISA
7000-7FFF slot 7 EISA
-------------------------------------------------------------------------------
0401-04D6 ---- used by EISA systems only
0401 r/w DMA channel 0 word count byte 2 (high)
0403 r/w DMA channel 1 word count byte 2 (high)
0405 r/w DMA channel 2 word count byte 2 (high)
0407 r/w DMA channel 3 word count byte 2 (high)
040A w extended DMA chaining mode register, channels 0-3
bit 7-5 reserved
bit 4 = 0 generates IRQ13
= 1 generates terminal count
bit 3 = 0 do not start chaining
= 1 programming complete
bit 2 = 0 disable buffer chaining mode (default)
= 1 enable buffer chaining mode
bit 1-0 DMA channel select
040A r channel interrupt (IRQ13) status register
bit 7-5 interrupt on channels 7-5
bit 4 reserved
bit 3-0 interrupt on channels 3-0
040B w DMA extended mode register for channels 3-0.
bit settings same as 04D6
bit 7 = 0 enable stop register
bit 6 = 0 terminal count is an output for this channel
(default)
bit 5-4 DMA cycle timing
= 00 ISA-compatible (default)
= 01 type A timing mode
= 10 type B timing mode
= 11 burst DMA mode
bit 3-2 Address mode
= 00 8-bit I/O, count by bytes (default)
= 01 16-bit I/O, count by words, address shifted
= 10 32-bit I/O, count by bytes
= 11 16-bit I/O, count by bytes
bit 1-0 DMA channel select
-------------------------------------------------------------------------------
0461 r/w Extended NMI status/control register
bit 7 = 1 NMI pending from fail-safe timer (read only)
bit 6 = 1 NMI pending from bus timeout NMI status (read
only)
bit 5 = 1 NMI pending (read only)
bit 4 reserved
bit 3 = 1 bus timeout NMI enable (read/write)
bit 2 = 1 fail-safe NMI enable (read/write)
bit 1 = 1 NMI I/O port enable (read/write)
bit 0 RSTDRV. bus reset (read/write)
= 0 normal bus reset operation
= 1 reset bus asserted
0462 w Software NMI register. writing to this register causes an NMI
if NMI's are enabled
bit 7 = 1 generates an NMI
0464 r bus master status latch register (slots 1-8). identifies the
last bus master that had control of the bus
bit 7 = 0 slot 8 had control last
bit 6 = 0 slot 7 had control last
bit 5 = 0 slot 6 had control last
bit 4 = 0 slot 5 had control last
bit 3 = 0 slot 4 had control last
bit 2 = 0 slot 3 had control last
bit 1 = 0 slot 2 had control last
bit 0 = 0 slot 1 had control last
0465 r bus master status latch register (slots 9-16)
bit 7 = 0 slot 16 had control last
bit 6 = 0 slot 15 had control last
bit 5 = 0 slot 14 had control last
bit 4 = 0 slot 13 had control last
bit 3 = 0 slot 12 had control last
bit 2 = 0 slot 11 had control last
bit 1 = 0 slot 10 had control last
bit 0 = 0 slot 9 had control last
-------------------------------------------------------------------------------
0481 r/w DMA channel 2 address byte 3 (high)
0482 r/w DMA channel 3 address byte 3 (high)
0483 r/w DMA channel 1 address byte 3 (high)
0487 r/w DMA channel 0 address byte 3 (high)
0489 r/w DMA channel 6 address byte 3 (high)
048A r/w DMA channel 7 address byte 3 (high)
048B r/w DMA channel 5 address byte 3 (high)
04C6 r/w DMA channel 5 word count byte 2 (high)
04CA r/w DMA channel 6 word count byte 2 (high)
04CE r/w DMA channel 7 word count byte 2 (high)
-------------------------------------------------------------------------------
04D0 w IRQ 0-7 interrupt edge/level registers
bit 7 = 1 IRQ 7 is level sensitive
bit 6 = 1 IRQ 6 is level sensitive
bit 5 = 1 IRQ 5 is level sensitive
bit 4 = 1 IRQ 4 is level sensitive
bit 3 = 1 IRQ 3 is level sensitive
bit 2-0 reserved
04D1 w IRQ 8-15 interrupt edge/level registers
bit 7 = 1 IRQ 15 is level sensitive
bit 6 = 1 IRQ 14 is level sensitive
bit 5 = 1 reserved
bit 4 = 1 IRQ 12 is level sensitive
bit 3 = 1 IRQ 11 is level sensitive
bit 2 = 1 IRQ 10 is level sensitive
bit 1 = 1 IRQ 9 is level sensitive
bit 0 reserved
04D4 w extended DMA chaining mode register, channels 4-7
bit 7-5 = 0 reserved
bit 4 = 0 generates IRQ 13
= 1 generates terminal count
bit 3 = 0 do not start chaining
= 1 programming complete
bit 2 = 0 disable buffer chaining mode (default)
= 1 enable buffer chaining mode
bit 1-0 DMA channel select
04D6 w DMA extended mode register for channels 4-7
bit settings same as 04B
bit 7 = 0 enable stop register
bit 6 = 0 terminal count is an output for this channel
(default)
bit 5-4 DMA cycle timing
= 00 ISA-compatible (default)
= 01 type A timing mode
= 10 type B timing mode
= 11 burst DMA mode
bit 3-2 Address mode
= 00 8-bit I/O, count by bytes (default)
= 01 16-bit I/O, count by words, address shifted
= 10 32-bit I/O, count by bytes
= 11 16-bit I/O, count by bytes
bit 1-0 DMA channel select
-------------------------------------------------------------------------------
0620-0627 ---- PC network (adapter 1)
0628-062F ---- PC network (adapter 2)
-------------------------------------------------------------------------------
06E2-06E3 ---- data aquisition (adapter 1)
-------------------------------------------------------------------------------
0790-0793 ---- cluster (adapter 1)
-------------------------------------------------------------------------------
0800-08FF ---- I/O port access registers for extended CMOS RAM or SRAM
(256 bytes at a time)
Sometimes plain text can be seen here.
-------------------------------------------------------------------------------
0A20-0A23 ---- Token Ring (adapter 1)
0A24-0A27 ---- Token Ring (adapter 2)
-------------------------------------------------------------------------------
0AE2-0AE3 ---- cluster (adapter 2)
0B90-0B93 ---- cluster (adapter 2)
-------------------------------------------------------------------------------
0C00 r/w page register to write to SRAM or I/O
-------------------------------------------------------------------------------
0C80-0C83 ---- system board ID registers
-------------------------------------------------------------------------------
1390-1393 ---- cluster (adapter 3)
-------------------------------------------------------------------------------
2100-210F ---- IBM XGA (eXtended Graphics Adapter 8514/A)
2110-211F ---- IBM XGA (eXtended Graphics Adapter 8514/A)
2120-212F ---- IBM XGA (eXtended Graphics Adapter 8514/A)
2130-213F ---- IBM XGA (eXtended Graphics Adapter 8514/A)
2140-214F ---- IBM XGA (eXtended Graphics Adapter 8514/A)
2150-215F ---- IBM XGA (eXtended Graphics Adapter 8514/A)
2160-216F ---- IBM XGA (eXtended Graphics Adapter 8514/A)
2150-217F ---- IBM XGA (eXtended Graphics Adapter 8514/A)
-------------------------------------------------------------------------------
2390-2393 ---- cluster (adapter 4)
-------------------------------------------------------------------------------
3220-3227 ---- serial port 3, description same as 03F8
3228-322F ---- serial port 4, description same as 03F8
-------------------------------------------------------------------------------
3540-354F ---- IBM SCSI (Small Computer System Interface) adapter
3550-355F ---- IBM SCSI (Small Computer System Interface) adapter
3560-356F ---- IBM SCSI (Small Computer System Interface) adapter
3570-357F ---- IBM SCSI (Small Computer System Interface) adapter
-------------------------------------------------------------------------------
4220-4227 ---- serial port, description same as 03F8
4228-422F ---- serial port, description same as 03F8
-------------------------------------------------------------------------------
42E0-42EF ---- GPIB (General Purpose Interface Bus, IEEE 488 interface)
42E1 r/w GPIB (adapter 2)
-------------------------------------------------------------------------------
5220-5227 ---- serial port, description same as 03F8
5228-522F ---- serial port, description same as 03F8
-------------------------------------------------------------------------------
62E0-62EF ---- GPIB (General Purpose Interface Bus, IEEE 488 interface)
62E1 r/w GPIB (adapter 3)
-------------------------------------------------------------------------------
82E0-82EF ---- GPIB (General Purpose Interface Bus, IEEE 488 interface)
82E1 r/w GPIB (adapter 4)
-------------------------------------------------------------------------------
82F8-82FF ---- serial port, description same as 03F8
83F8-83FF ---- serial port, description same as 03F8
-------------------------------------------------------------------------------
A220 ???? soundblaster support in AMI Hi-Flex BIOS ????
-------------------------------------------------------------------------------
A2E0-A2EF ---- GPIB (General Purpose Interface Bus, IEEE 488 interface)
A2E1 r/w GPIB (adapter 5)
-------------------------------------------------------------------------------
AFFF r/w plane 0-3 system latch (video register)
-------------------------------------------------------------------------------
B220-B227 ---- serial port, description same as 03F8
B228-B22F ---- serial port, description same as 03F8
-------------------------------------------------------------------------------
C220-C227 ---- serial port, description same as 03F8
C228-C22F ---- serial port, description same as 03F8
-------------------------------------------------------------------------------
D220-D227 ---- serial port, description same as 03F8
D228-D22F ---- serial port, description same as 03F8
-------------------------------------------------------------------------------
C2E0-C2EF ---- GPIB (General Purpose Interface Bus, IEEE 488 interface)
C2E1 r/w GPIB (adapter 6)
-------------------------------------------------------------------------------
E2E0-E2EF ---- GPIB (General Purpose Interface Bus, IEEE 488 interface)
E2E1 r/w GPIB (adapter 7)
-------------------------------------------------------------------------------
