Page 6
Manual 41417-159-2
EMC-FDM Manual
OB1 is defined as follows:
Parallel Port
I/O Enable
Parallel Port
Enable
Printer Port
Select
COM Port
Interrupt
COM Port
Base
Address
Card Enable
(bit 7)
(bit 6)
(bit 5)
(bits 4, 3)
(bits 2, 1)
(bit 0)
1 = Enable
ouput
1 = Enable
1 = 378 IRQ7
00 = Disabled
00 = Disabled
1 = Enable
card
0 = Enable
input
0 = Disable
0 = 278 IRQ5
01 = IRQ3
01 = 2F8h
0 = Disable
card, IRQs
10 = IRQ4
10 = 3E8h
11 = IRQ9(2)
11 = 2E8h
Table 2: OB1 Register.
Parallel port In/Out - Normally set to 1 to enable output to the parallel port. Set to 0 to input
data from a parallel device such as a scanner. Note that the DIR bit, which is bit 5 of register
27Ah or 37Ah, must be set to 1 via application software before the parallel port accepts input.
Bit 7 has no effect when bit 6 = 0.
Parallel port enable - If 0, disables the parallel port registers and interrupt. A value of 1
enables the port.
Printer port select - If set to 1, selects a base address for the parallel port of 378h (LPT1:) and
interrupt IRQ7. If clear, selects 278h and IRQ5.
COM port interrupt select - Encoded as follows:
00 Disabled. COM port uses no interrupt but can be written to.
01 Use IRQ3 (this is normally COM2)
10 Use IRQ4 (this is normally COM1)
11 Use IRQ9
COM port base address and enable - Encoded as follows:
00 Disabled. COM port will not respond.
01 Base address 2F8. This is normally COM2.
10 Base address 3E8. This is normally COM3.
11 Base address 2E8. This is normally COM4.
Card enable - CDEN must be set to 1 to enable the EMC-FDM. Note that setting CDEN to 0
disables all access to the registers, as well as disabling all interrupts.
