Windows Platform Design Notes
Designing Hardware for the Microsoft Windows Family of Operating Systems
Serial Port Console Redirection Table
This document defines the content of the Serial Port Console Redirection Table. This table is
used to indicate whether a serial port or a non-legacy UART interface is available for use with
Microsoft® Windows® Emergency Management Services (EMS).
The table provides information about the configuration and use of the serial port or non-legacy
UART interface. On a system where the BIOS or system firmware uses the serial port for console
input/output, this table should be used to convey information about the settings, to ensure a
seamless transition between the firmware console output and Windows EMS output.
This table must be located in system memory with other ACPI tables, and it must be referenced in
the ACPI RSDT table.
Version 1.00 — January 11, 2002
SERIAL PORT CONSOLE REDIRECTION TABLE SPECIFICATION LICENSE
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Serial Port Console Redirection Table — 2
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(a) You must implement the table in its entirety (e.g., all fields) and without modification (e.g., byte length, offset, and permissible
values as described in the Specification).
(b) Your license rights to the Specification are conditioned upon you not creating, modify, or distributing your Firmware in a way that
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Serial Port Console Redirection Table — 3
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© 2000 Microsoft Corporation. All rights reserved.
Version 1.00 —
© 2000 - 2002 Microsoft Corporation. All rights reserved.
Serial Port Console Redirection Table — 4
Serial Port Console Redirection Table Format
Field
Byte
Length
Byte
Offset
Description
Header
Signature
4
0
Length
4
4
Revision
Checksum
OEMID
OEM Table ID
1
1
6
8
8
9
10
16
OEM Revision
4
24
Creator ID
4
28
Creator Revision
4
32
Interface Type
1
36
Reserved
Base Address
3
12
37
40
‘SPCR’. Signature for the Serial Port Console
Redirection Table.
Length, in bytes, of the entire Serial Port Console
Redirection Table.
1
Entire table must sum to zero.
OEM ID.
For the Serial Port Console Redirection Table, the
table ID is the manufacturer model ID.
OEM revision of Serial Port Console Redirection
Table for supplied OEM Table ID.
Vendor ID of utility that created the table. For the
DSDT, RSDT, SSDT, and PSDT tables, this is the ID
for the ASL Compiler.
Revision of utility that created the table. For the
DSDT, RSDT, SSDT, and PSDT tables, this is the
revision for the ASL Compiler.
Indicates the type of the register interface:
0 = full 16550 interface
1 = full 16450 interface (must also accept writing to
the 16550 FCR register)
2-255 = reserved
Must be 0.
The base address of the Serial Port register set
described using the Generic Register Address
Structure*.
0 = console redirection disabled
Interrupt Type
1
52
Note:
COM1 (0x3F8) would be:
Integer Form: 0x 01 08 00 00 00000000000003F8
Viewed in Memory: 0x01080000F803000000000000
COM2 (Ox2F8) would be:
Integer Form: 0x 01 08 00 00 00000000000002F8
Viewed in Memory: 0x01080000F802000000000000
Interrupt type(s) used by the UART.
Bit[0] PC-AT-compatible dual-8259 IRQ interrupt
Bit[1] I/O APIC interrupt (Global System Interrupt)
Bit[2] I/O SAPIC interrupt (Global System Interrupt)
(IRQ)
Bit[3:7] reserved (must be 0)
0 = not supported
1 = supported
Platforms with both a dual-8259 and an I/O APIC or
I/O SAPIC must set the IRQ bit (Bit[0]) and the
corresponding Global System Interrupt bit.). E.g. an
system trhat supported 8259 and SAPIC would be 5
Version 1.00 —
© 2000 - 2002 Microsoft Corporation. All rights reserved.
Serial Port Console Redirection Table — 5
Field
Byte
Length
1
Byte
Offset
53
Global System
Interrupt
4
54
Baud Rate
1
58
Parity
1
59
Stop Bits
1
60
Flow Control
1
61
Terminal Type
1
62
Reserved
PCI Device ID
PCI Vendor ID
PCI Bus Number
1
2
2
1
63
64
66
68
PCI Device Number
1
69
PCI Function
Number
PCI Flags
1
70
4
71
PCI Segment
1
75
Reserved
4
76
IRQ
Description
The PC-AT-compatible IRQ used by the UART.
2-7, 9-12, 14-15 = valid IRQs respectively
0-1, 8, 13, 16-255 = reserved
Valid only if Bit[0] of the Interrupt Type field is set.
The I/O APIC or I/O SAPIC Global System Interrupt
used by the UART.
Valid only if Bit[1] or Bit[2] of the Interrupt Type field is
set.
The baud rate the BIOS used for redirection.
3 = 9600
4 = 19200
6 = 57600
7 = 115200
0-2, 5, 8 - 255 = reserved
0 = No Parity
1-255 = reserved
1 = 1 Stop bit
0,2-255 = reserved
Bit[0] = DCD required for transmit
Bit[1] = RTS/CTS hardware flow control
Bit[2] = XON/XOFF software control
Bit[3:7] = reserved, must be zero
The terminal protocol the BIOS was using for console
redirection:
0 = VT100
1 = VT100+
2 = VT-UTF8
3 = ANSI
4-255 = reserved
Must be 0
Must be 0xFFFF if it is not a PCI device
Must be 0xFFFF if it is not a PCI device
PCI Bus Number if table describes a PCI device
Must be 0x00 if it is not a PCI device
PCI Slot Number if table describes a PCI device
Must be 0x00 if it is not a PCI device
PCI Function Number if table describes a PCI device
Must be 0x00 if it is not a PCI device
PCI Compatibility flags bitmask. Should be zero by
default.
Bit[0] = Operating System should NOT suppress PNP
device enumeration or disable power management for
this device. Must be 0 if it is not a PCI device
Bits 1-31 = RESERVED, must be zero.
PCI segment number.
For systems with fewer than 255 PCI buses, this
number must be 0.
Must be 0
* The Generic Register Address Structure can be found on the Microsoft web site at
http://www.microsoft.com/hwdev/onnow/download/LFreeACPI.doc
Version 1.00 —
© 2000 - 2002 Microsoft Corporation. All rights reserved.
Serial Port Console Redirection Table — 6
Revision History
Date
2/15/00
3/1/00
Rev
.10
.50
Description
Created
‘SPCR’. Signature
Data added
3/20/00
3/22/00
.55
.56
3/23/00
4/24/00
.56a
.6
Data revised to include port and irq
Clarified port identification
Added ability to disable redirection
Added pointer to the Generic Register Address
Structure
Formatting, disclaimer, copy editing
Posted on web for WinHEC
4/24/00
.6
Public review draft published
5/25/00
.61
Correction to BASE_ADDRESS description
5/25/00
.61
Public review draft published
5/31/00
.7
5/31/00
.71
Correction to BASE_ADDRESS description examples
Added 16540 interface
Changed the info on the GRAS from a note to a “*”
5/31/00
.71
Public review draft published
6/1/00
.72
7/12/00
.75
7/26/00
.76
8/10/00
.77
9/22/00
.78
Changed GRAS COM port examples to be littleendian
Added text to the end of the line
Fixed IRQ Description
Fixed various format issues
Added PCI bus information
Update to PCI field name “Device Number”
Changed intro language to include non-legacy UART
Changed interrupt information, adding APIC and
SAPIC
Added flow control
Added PCI Segment
10/25/00
.80
10/1/01
1/11/02
.95
1.00
Fixed PCI Flags section
Added Terminal Types
Added 16450 FCR info
removed language codes
adding updated licensing
spec to 1.00
Version 1.00 —
© 2000 - 2002 Microsoft Corporation. All rights reserved.