Review: Intelligent Multiport Serial Boards

Comtrol, Cyclades, DigiBoard, and Stallion boards are tested in Linux Journal's hardware review. If you need more serial ports than you currently have, read on.
Cyclades Cyclom-8Y

The Cyclom-8Y series of boards features two 12.5 MHz Cirrus Logic CD-1400 RISC UARTs. The CD-1400 UARTs handle flow control and special character recognition and also have 12 byte transmit and receive FIFOs, as well as a holding and shift register for each port. The Cyclom-8Y boards support full RS232C modem control and hardware flow control signals (except for the Cyclom-8Ys, which have no RTS signal) and will support speeds up to 115.2 Kbps. Each Cyclom-8Y board needs one interrupt (IRQ) selectable from 5, 9, 10, 11, 12, and 15, and an 8K block of dual-ported RAM selectable from 0xA0000-0xEE000. Both IRQ and I/O address are set with a DIP switch on the board. Four boards can be used simultaneously, each requiring its own IRQ and I/O address.

The driver for the Cyclom boards is included in kernel sources starting with version 1.1.74 and newer. The Cyclom-8Y boards are supported by Cyclades, which was the first company to offer a vendor-supported driver for an intelligent multiport board under Linux. There are four 8-port models in the Cyclom-8Y line: the Cyclom-8Ys with on-board RJ12 connectors (no RTS signal), at US $459.00; Cyclom-8Yo with an octopus cable with DB25 connectors, priced at US $511.00; and the Cyclom-8Yb and Cyclom-8Yb+ with DB25 connectors in an external box (the Cyclom-8Yb+ also has surge protection), at US $599.00 and US $699.00, respectively.

DigiBoard PC/8e

The DigiBoard PC/8e board is driven by an 12.5 MHz Intel 80186 CPU to handle I/O processing. It also uses 64K on-board RAM for data buffering. Seven PC/8e boards can be used in one system, each requiring one four-byte I/O address selectable from 0x100, 0x110, 0x120, 0x200, 0x220, 0x300, and 0x320 with a DIP switch. The nice thing about this board is that the DIP switch is located on the back of the card, so you can see and change the I/O address without opening your computer. An 8K block of dual-ported RAM is also required, but this can be shared among all boards. This address is selectable from 0xC0000-0xEFFFF by the PC/8e driver. No IRQ is required.

PC/8e boards support RS232C full modem and hardware flow control signals at speeds up to 115.2 Kbps. The driver for this board is supported by Troy De Jongh (an employee of DigiBoard), not by DigiBoard. The PC/8e host adaptor is US $795.00 plus US $90.00 for a DB25 connector octopus cable, US $110.00 for a DB25 connector box, or US $110.00 for an RJ45 connector box.

Stallion EasyIO/8, and EasyConnection 8/32

Stallion boards employ the same CD-1400 RISC UARTs as the Cyclades boards, with the same features. There are two models of the Stallion 8-port boards: the EasyIO/8, and the EasyConnection 8/32 modular board. Both boards need an 8 byte I/O address, selectable from 0x200-0x3FF with a DIP switch, and an IRQ selectable from 3, 4, 5, 7, 10, 11, 12 and 15, with the driver. The IRQ can be shared by all boards on an EISA bus machine. The EasyConnection 8/32 board needs an additional 32-byte secondary I/O address, selectable from 0x200-0x3FF via the driver, also sharable among all EasyConnection 8/32 boards. Any combination of four EasyIO/8 and EasyConnection 8/32 boards are supported by the driver.

EasyIO/8 boards offer 8 RS232C serial ports at speeds up to 115.2 Kbps, with full modem and hardware flow control. EasyConnection 8/32 boards offer 8-32 ports supporting RS232D full modem and hardware flow control signals at speeds up to 115.2 Kbps and, optionally, RS422A signals, also at 115.2 Kbps. The EasyConnection 8/32 is offered with 8 or 16 port modules, which can be used in any combination together to form a 32 port module. Each module has its own CD-1400 chips to support the ports on that module. The modules are nicely made and also have wall mount brackets on the back. The driver for this series of boards is supported by Greg Ungerer (an employee of Stallion), not by Stallion. The EasyIO/8 is available with a DB25 connector octopus cable, or an RJ45 connector box for US $595.00. The EasyConnection 8/32 host adaptor is US $300.00. Eight-port modules are priced at US $595 for RS232 connector boxes with RJ45 or DB25 connectors, and US $795.00 for a RS232/RS422 DB25 connector box. Sixteen-port modules with RJ45 connectors cost US $845.00, and 16-port modules with DB25 connectors are US $945.00.

Common Features

Several common features were shared among all products:

  • All manufacturers offers five-year warranties and 30-day money-back guarantees.

  • The ISA/EISA buses are the only bus types supported, although support for PCI cards is in progress by some vendors.

  • Everyone was extremely helpful; even the people who support the driver in their spare time were very responsive.