Int 17/AX=0200h/BX=5050h

Enhanced Parallel Port (EPP) BIOS - INSTALLATION CHECK

AX = 0200h
BX = 5050h ('PP')
CH = 45h   ('E')
DX = printer port number (00h-02h)

Return:
AH = status
00h if installed and port is an enhanced parallel port
CX:AL = installed BIOS type
5050h:45h ('PPE') if EPP v3.0+ BIOS installed
4550h:50h ('EPP') if EPP v1.0 BIOS installed
---EPP 1.0, 3.0---
DX:BX -> far entry point to Advanced BIOS (see #00632)
---EPP Revision 7---
DX = EPP I/O base address
ES:BX -> far entry point to EPP BIOS (see #00632,#00633)
03h if installed but specified port not supported
CF set

Program: The Enhanced Parallel Port BIOS provides support for parallel port peripherals using the enhanced modes of the IEEE 1284.

See Also: AH=E0h - MEM 0040h:0008h - MEM 0040h:00DCh



(Table 00632)
Call EPP BIOS entry point with:.
DL = port number (v1.0,v3.0).
DX = (Revision 7) EPP port I/O base address.
AH = function
00h Query Configuration
Return:
AH = 00h if successful
AL = IRQ number used by port or FFh if no IRQ
BH = EPP BIOS revision (major in high nybble,
minor in low nybble)
BL = I/O capabilities (see #00635)
ES:DI -> ASCIZ driver information/version text
---v1.0,v3.0---
CX = I/O port base address for parallel port
---Revision 7---
CL = EPP chipset code (see #00636)
CH = hardware manufacturer's product code
01h Set Mode
AL = mode bits (see #00637)
Return:
AX,BX destroyed
02h Get Mode
Return:
AL = mode bits (see also #00637)
bit 7:
EPP port interrupts enabled
AH = 00h
CF clear
BX destroyed
03h Interrupt Control
AL = subfunction
00h enable parallel port interrupts
01h disable parallel port interrupts
Return:
AH = status (00h,05h,06h) (see also #00634)
04h EPP Reset
Return:
AH = 00h if successful
AL destroyed
05h perform Address-Write/Device-Select I/O cycle
AL = device address
Return:
AH = status
AL destroyed
06h perform Address-Read I/O cycle
Return:
AL = returned address/device data
AH = status
07h write byte
AL = data byte to write
Return:
AH = status
08h output block of data
DS:SI -> block of data to be sent to parallel port
CX = number of bytes to output
Return:
AH = status (see #00634)
CX = number of unsent bytes
09h read byte of data
Return:
AH = status (see #00634)
AL = byte read from parallel port
0Ah read block of data
ES:DI -> buffer for received data
CX = number of bytes to read from paralle port
Return:
AH = status (see #00634)
ES:DI buffer filled if successful
CX = number of bytes not transferred
0Bh Address/Byte-Read
AL = device address
Return:
AH = status (see #00634)
AL = byte read if successful
0Ch Address/Byte-Write
AL = device address
DH = data byte (v1.0,v3.0)
CL = data byte (Revision 7)
Return:
AH = status (see #00634)
0Dh Address/Block-Read
AL = device address
ES:DI -> buffer for received data
CX = number of bytes to read
Return:
AH = status (see #00634)
CX = number of bytes NOT transferred
0Eh Address/Block-Write
AL = device address
ES:DI -> data to be sent (v1.0,v3.0)
DS:SI -> data to be send (Revision 7)
CX = number of bytes to write
Return:
AH = status (see #00634)
CX = number of bytes NOT transferred
0Fh Lock Port
AL = multiplexor port number
bits 7-4:
Daisy chain port number (1-8)
bits 3-0:
Mux device port number (1-8, 0 if no mux)
Return:
AH = status (00h,03h,05h) (see #00634)
10h Unlock Port
AL = multiplexor port number
bits 7-4:
Daisy chain port number (1-8)
bits 3-0:
Mux device port number (1-8, 0 if no mux)
Return:
AH = status (00h,03h,05h) (see #00634)
11h Device Interrupt
BL = multiplexor port number
00h if no multiplexor, else mux device port (01h-08h)
AL = subfunction
00h disable device interrupts
01h enable device interrupt
ES:DI -> interrupt event handler
Return:
AH = status (00h,03h,05h,06h) (see #00634)

Note: AMI BIOS v1.00.12.AX1T ignores the multiplexor port number; it also always sets INT 0F to the address specified in ES:DI 12h Real-Time Mode AL = subfunction 00h check whether any real-time devices present 01h add (advertise) real-time device 02h remove real-time device

Return:
AH = status (00h,05h,06h,07h) (see #00634)
AL = real-time devices present? (00h no, 01h yes)

Note: Unlike all other functions, this one does not use DL/DX

Return:
AH = status (see #00634)
CF clear if successful
CF set on error
BX destroyed

See Also: #00633



(Table 00633)
Call EPP BIOS (Revision 7) entry point multiplexor functions with:.
DX = EPP port base I/O address.
AH = function
40h Query Mux
Return:
AH = status (see #00634)
AL = currently-selected port
CH = status flags
bit 0:
Channel locked
bit 1:
Interrupt pending
BH destroyed

Note: The PhoenixBIOS v4.0 documentation lists BL as the currently-selected port and AL as the status flags 41h Query Device Port AL = EPP multiplex device port (1-8)

Return:
AH = status (see #00634)
CH = status flags (see #00638)
BX = EPP product/device ID (0000h if undefined)

Note: The PhoenixBIOS v4.0 documentation lists AL as the status flags and CX as the device ID 42h Set Product ID AL = EPP multiplex device port (1-8) CX = EPP product ID

Return:
AH = status (see #00634)
BX destroyed
50h Query Daisy Chain
AL = EPP multiplexor device port (1-8)
Return:
AH = status (see #00634)
CH = status flags
bit 0:
Channel locked
bit 1:
Interrupt pending
BL = currently-selected device
BH = EPP daisy chain revision (high nybble = major)
CL = daisy-chain depth (00h if no daisy chain)
ES:DI -> ASCIZ driver vendor identification string

Note: The PhoenixBIOS v4.0 documentation lists AH=51h as "Query Daisy Chain" and BL as the multiplexor port; it also lists AL as status flags on return 51h Rescan Daisy Chain (dynamically reassign port numbers) AL = EPP multiplexor device port (1-8)

Return:
AH = status (see #00634)
BX destroyed

Note: The PhoenixBIOS v4.0 documentation lists AH=50h as "Rescan Daisy Chain" and BL as the multiplexor port

Notes: These functions are only valid if a port multiplexor or daisy chain is present. PhoenixBIOS 4.0 documents function 50h as "Rescan" and 51h as "Query Daisy Chain"

See Also: #00632 - INT 2D/AL=DCh



(Table 00634)
Values for EPP BIOS function status:
00h    successful
02h    unsupported command/feature
03h    unsupported parallel port
05h    unsupported in current mode
06h    invalid subfunction
07h    already ???
20h    multiplexor not present (AMI)
40h    multiplexor not present
41h    multiplexor currently locked
80h    I/O timeout
FFh    invalid/unsupported function

See Also: #00632 - #00633

Bitfields for EPP (v3.0, Revision 7) I/O capabilities: Bit(s) Description (Table 00635) 0 multiplexor present 1 PS/2 bi-directional capable 2 daisy chain present 3 ECP capable 4 EPP software emulation supported 5 EPP capable 6 fast Centronics supported 7 standard EPP I/O map

See Also: #00632

(Table 00636) Values for EPP (Revision 7) chipset code: 00h Intel SL 01h FarPoint Communications 02h SMC 03h Chips&Technologies 04h Western Digital 05h National Semiconductor

See Also: #00632

Bitfields for EPP BIOS mode bits: Bit(s) Description (Table 00637) 0 set compatibility mode 1 set bi-directional mode 2 set EPP mode ---Revision 7,v3.0--- 3 set ECP mode 4 set EPP software emulation 5 set fast Centronics mode 6-7 reserved (0)

See Also: #00632 - #M0053

Bitfields for EPP BIOS multiplex status flags: Bit(s) Description (Table 00638) 0 port is selected 1 port is locked 2 interrupts are enabled 3 interrupt pending

See Also: #00633

Category: Vendor-specific BIOS Extensions - Int 17h - E

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