5. Multiport Serial Boards/Cards

5.1 Standard PC Serial Boards

Standard PC serial boards (COM1 - COM4) can be used to, to connect external serial devices (modems, serial mice, etc...). Since PC's no longer come with them (but have the chips for this purpose mounted on the motherboard), they are hard to find in retail stores. An internal modem for the ISA bus may include a built-in serial port.

Note: due to address conflicts, you cannot use COM4 and IBM8514 video board (or clones) simultaneously. This is due to a bug in the IBM8514 board.

5.2 Dumb Multiport Serial Boards (with 8250/16450/16550A UART's)

They are also called "serial adapters".
* => "setserial" shows details of configuring

• AST FourPort and clones (4 ports) *
• Accent Async-4 (4 ports) *
• Arnet Multiport-8 (8 ports)
• Bell Technologies HUB6 (6 ports)
• Boca BB-1004 (4 ports), BB-1008 (8 ports), BB-2016 (16 ports; See the mini-howto) *
• Boca IOAT66 or? ATIO66 (6 ports, Linux doesn't support it's IRQ sharing ?? Uses odd-ball 10-cond RJ45-like connectors)
• Boca 2by4 (4 serial ports, 2 parallel ports)
• Byterunner (claims low prices)
• Computone ValuePort V4-ISA (AST FourPort compatible) *
• Digi PC/8 (8 ports)
• GTEK BBS-550 (8 ports; See the mini-howto)
• HUB-6 See Bell Technologies.
• Longshine LCS-8880, Longshine LCS-8880+ (AST FourPort compatible) *
• Moxa C104, Moxa C104+ (AST FourPort compatible) *
• PC-COMM (4 ports)
• Sealevel Systems COMM-2 (2 ports), COMM-4 (4 ports) and COMM-8 (8 ports)
• SIIG I/O Expander 2S IO1812 (4 ports)
• STB-4COM (4 ports)
• Twincom ACI/550
• Usenet Serial Board II (4 ports) *

In general, Linux will support any serial board which uses a 8250, 16450, 16550, 16550A, 16650 (or compatible) UART, or an internal modem which emulates one of the above UARTs.

Note: the BB-1004 and BB-1008 do not support DCD and RI lines, and thus are not usable for dialin modems. They will work fine for all other purposes. Hayes ESP is supported after kernel version 2.1.15.

5.3 Intelligent Multiport Serial Boards

Make sure that a Linux compatible driver is available. This list is a little out of date.

• Comtrol RocketPort (36MHz ASIC; 4, 8, 16 or 32 ports)
  contact: info@comtrol.com or http://www.comtrol.com
  driver status: supported by Comtrol
  driver location: ftp://tsx-11.mit.edu/pub/linux/packages/comtrol
• Computone IntelliPort II (16MHz 80186; 4, 8, or 16 ports),
  IntelliPort II EXpandable (20MHz 80186; 16 - 64 ports)
  contact: Michael H. Warfield, mhw@wittsend.atl.ga.us
  driver status: pre-ALPHA
• Cyclades Cyclom-Y (Cirrus Logic CD1400 UARTs; 8 - 32 ports),
  Cyclom-Z (25MHz MIPS R3000; 8 - 128 ports)
  contact: sales@cyclades.com or http://www.cyclades.com
  driver status: supported by Cyclades
  driver location: ftp://ftp.cyclades.com/pub/cyclades and included in Linux kernel since version 1.1.75
• Decision PCCOM8 (8 ports)
  contact: pccom8@signum.se
  driver location: ftp://ftp.signum.se/pub/pccom8
• Digi PC/Xi (12.5MHz 80186; 4, 8, or 16 ports),
  PC/Xe (12.5/16MHz 80186; 2, 4, or 8 ports),
  PC/Xr (16MHz IDT3041; 4 or 8 ports),
  PC/Xem (20MHz IDT3051; 8 - 64 ports)
  contact: sales@dgii.com or http://www.dgii.com
  driver status: supported by Digi
  driver location: ftp://ftp.dgii.com/drivers/linux and included in Linux kernel since version 2.0
• Digi COM/Xi (10MHz 80188; 4 or 8 ports)
  contact: Simon Park, si@wimpol.demon.co.uk
  driver status: ALPHA
  note: Simon is often away from email for months at a time due to his job. Mark Hatle, fray@krypton.mankato.msus.edu has graciously volunteered to make the driver available if you need it. Mark is not maintaining or supporting the driver.
• Equinox SuperSerial Technology (30MHz ASIC; 2 - 128 ports)
  contact: sales@equinox.com or http://www.equinox.com
  driver status: supported by Equinox
  driver location: ftp://ftp.equinox.com/library/sst
• GTEK Cyclone (16C654 UARTs; 6, 16 and 32 ports),
  SmartCard (24MHz Dallas DS80C320; 8 ports),
  BlackBoard-8A (16C654 UARTs; 8 ports),
  PCSS (15/24MHz 8032; 8 ports)
  contact: spot@gtek.com or http://www.gtek.com
  driver status: supported by GTEK
  driver location: ftp://ftp.gtek.com/pub
• Hayes ESP (COM-bic; 1 - 8 ports)
  contact: Andrew J. Robinson, arobinso@nyx.net or http://www.nyx.net/~arobinso
  driver status: Will be supported by Linux kernel (1998). Also supported by author
  driver location: http://www.nyx.net/~arobinso and included in Linux kernel since version 2.1.15. Setserial 2.15+ supports.
• Maxpeed SS (Toshiba; 4, 8 and 16 ports)
  contact: info@maxpeed.com or http://www.maxpeed.com
  driver status: supported by Maxpeed
  driver location: ftp://maxpeed.com/pub/ss
• Moxa C218 (12MHz 80286; 8 ports),
  Moxa C320 (40MHz TMS320; 8 - 32 ports)
  contact: info@moxa.com.tw or http://www.moxa.com.tw
  driver status: supported by Moxa
  driver location: ftp://ftp.moxa.com.tw/drivers/c218-320/linux
• SDL RISCom/8 (Cirrus Logic CD180; 8 ports)
  contact: sales@sdlcomm.com or http://www.sdlcomm.com
  driver status: supported by SDL
  driver location: ftp://ftp.sdlcomm.com/pub/drivers
• Specialix SX (25MHz T225; 8? - 32 ports),
  SIO/XIO (20 MHz Zilog Z280; 4 - 32 ports)
  contact: mailto:R.E.Wolff@BitWizard.nl
  driver status: BETA / Supported by Specialix
  driver location: http://www.BitWizard.nl/specialix/
  old driver location: ftp://metalab.unc.edu/pub/Linux/kernel/patches/serial
• Stallion EasyIO-4 (4 ports), EasyIO-8 (8 ports), and
  EasyConnection (8 - 32 ports) - each with Cirrus Logic CD1400 UARTs,
  Stallion (8MHz 80186 CPU; 8 or 16 ports),
  Brumby (10/12 MHz 80186 CPU; 4, 8 or 16 ports),
  ONboard (16MHz 80186 CPU; 4, 8, 12, 16 or 32 ports),
  EasyConnection 8/64 (25MHz 80186 CPU; 8 - 64 ports)
  contact: sales@stallion.com or http://www.stallion.com
  driver status: supported by Stallion
  driver location: ftp://ftp.stallion.com/drivers/ata5/Linux and included in linux kernel since 1.3.27

A review of Comtrol, Cyclades, Digi, and Stallion products was printed in the June 1995 issue of the Linux Journal. The article is available at http://www.ssc.com/lj/issue14.