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Prometheus CPU User Manual V1.44 Page 27
8.2 Serial Ports
Prometheus contains 4 serial ports. Each port is capable of transmitting at speeds of up to
115.2Kbaud. Ports COM1 and COM2 are built into the ZF Micro CPU chip. They consist of
standard 16550 type UARTs with 16-byte FIFOs. Ports COM3 and COM4 are derived from an
Exar 16C2850 dual UART chip and include 128-byte FIFOs. Ports 3 and 4 may be operated at
speeds up to 1.5Mbaud with installation of high-speed drivers as a custom option.
The serial ports use the following default system resources:
Port Address range IRQ
COM1 I/O 3F8 – 3FF 4
COM2 I/O 2F8 – 2FF 3
COM3 I/O 3E8 – 3EF 4
COM4 I/O 2E8 – 2EF 3
The settings of COM1 and COM2 may be changed in the system BIOS. Select the Advanced
menu, then I/O Device Configuration. Serial Port A is COM1, and Serial Port B is COM2. The
base address and interrupt level may be modified on this page.
The settings of COM3 and COM4 may be changed using a different procedure:
The addresses of these two ports are selected on the Advanced menu of the BIOS. Select
Advanced Chipset Control, then ISA I/O Chip Select Setup. I/O Window – io_cs1 is for COM3 and
I/O window – io_cs2 is for COM4. The only parameter that may be changed is the address. The
other settings must remain in their default values:
Window state: Enabled
Base Address: (user selectable)
Read/Write control: Read/Write
Window data width: 8-bits
Active Level: Active Low
Window size: 08
After making any desired changes, go to the top-level Exit menu and select Exit Saving
Changes.
The interrupt (IRQ) settings for COM3 and COM4 are selected with J10. COM3 may use IRQ4 or
IRQ9. COM4 may use IRQ3 or IRQ15. If both serial ports share the same IRQ, they may share
IRQ4 or IRQ5. See page 16 for serial port IRQ jumper settings.
8.3 Parallel Port
The parallel port (LPT1) is an IEEE-1284 compatible bidirectional port. It includes filtering for
reduced EMI operation. It operates in ECP mode (set up in the BIOS). The parallel port has the
following default configuration:
Port Mode Address range IRQ DMA
LPT1 ECP I/O 378 – 37F 7 3
The parallel port settings may be modified in the BIOS. Select Advanced menu, then I/O Device
Configuration. The above four settings may then be modified.