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Home >> Products >> I/O Connectivity ICs >> PCI Bridge >> MCS9845

 MCS9845 -- PCI to Dual Serial and ISA Controller

The MCS9845CV-BA is a PCI based single function I/O Adapter. It has two 16C450/16C550 compatible UART channels and ISA style interface to add external UARTS and Parallel Ports.

The MCS9845CV-BA has 32-Byte transmit and receive FIFO for each UART channel. MCS8935CV-BA performs serial-to-parallel conversions on data received from a Serial device, and parallel-to-serial conversions on data received from its CPU.

ISA Style interface is designed to add additional Serial / Parallel Ports by using external ISA peripherals. ISA interface can be used for Serial / Parallel port expansion through ISA : 4 Serial or 2 Serial + 1 Parallel.

The MCS9845CV-BA is ideally suited for PC applications, such as Add-On COM ports and Parallel Ports. It is available in 128-Pin QFP package & fabricated using an advanced submicron CMOS process to achieve low power drain and high-speed requirements.

MCS9845CV-BA is designed to be pin compatible with previous version of MCS9845CV. Existing designs of MCS9845 can be migrated to MCS9845CV-BA without any modification to system design. Software compatibility is also maintained between MCS9845, MCS9845CV-BA.


  • General
    • 5V Operation
    • Low Power
    • Fully compliant with PCI Local Bus Specification 2.3
    • Re-map function for Legacy Ports
    • Microsoft WHQL Complaint Drivers
    • Advanced testability through scan addition
  • Serial Port
    • Two 16C 450 / 550 compatible UARTs
    • Supports RS232, RS485 & RS422 modes
    • Bi-directional Speeds from 50 bps to 115200 bps / Port
    • Full Serial modem control
    • Supports Hardware Flow Control
    • 5, 6, 7, 8-bit Serial format support
    • Even, Odd, None, Space & Mark parity supported
    • On Chip 32 Byte FIFO's in Transmit, Receive paths for both Serial Ports
  • ISA Interface Bus
    • ISA style I/O interface for extending UARTs & Parallel Ports
    • 8 bit data bus @ 8MHz
    • 3 Address Lines
    • 4 Active-High Interrupts
    • 1 Active Low Interrupt
    • 4 External Chip Selects
  • Miscellaneous
    • Four -Wire SPI Interface for EEPROM
    • EEPROM read through PCI
    • Package:128-Pin QFP, RoHS
    • Operating Temperature : 0 to +70°C
Target Applications:
  • Generic Serial attached devices like Modem & Serial Mouse
  • Serial Networking / Monitoring Equipment
  • Data Acquisition System
  • POS Terminal & Industrial PC
  • Parallel / Printer Port based applications
  • Add-On I/O Cards-Serial / Parallel
  • Embedded systems-For I/O expansion
  • Industrial Control

 Block Diagram


 Selection Guide


Technical Documentation

 Product Brief, Product Introduction and Datasheet

MCS9845 Product Brief184.7 KB2010-03-09
MCS9845 Datasheet 834.2 KB2012-09-12
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MCS9845 Reliability Report 193 KB2011-12-07
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MCS9845 RoHS Report   
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Hardware Design Documentation

 Reference Schematics

MCS9845 PCI 2 Serial + 2 Parallel Reference Schematic 363.7 KBv1.002011-08-18
MCS9845 PCI 4 Serial + 1 Parallel Reference Schematic 349.7 KBv1.002011-08-18
MCS9845 PCI 6 Serial Reference Schematic 361.8 KBv1.002011-08-18

 Bill of Materials, Application Notes and Layout Guides

MCS9845 PCB Layout Guide 109.7 KBv1.002011-09-28
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 PCB Layout, Gerber and IBIS Model

MCS9845 IBIS Model 47.1 KB2011-11-14
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Driver TypeRevision Release DateDescriptionFile Size
Linux kernel native serial/parallel drivers 2014-03-20 Using Linux Standard Serial and Parallel Drivers661.8 KB
Windows 10/8.x/7/Vista/XP 64-bit Driver v2.0.4.02013-07-01 For 64-bit x86 CPU platform, WHCK certified413.1 KB
Windows 10/8.x/7/Vista/XP 32-bit Driver v2.0.4.02013-07-01 For 32-bit x86 CPU platform, WHCK certified338.4 KB
Windows CE 6.0 Driver v1.0.0.52009-01-21 For CEPC x86 platform1.4 MB
Windows CE 5.0 / Mobile 5 / Mobile 6 Driver v1.0.0.52009-01-22 For CEPC x86 platform1.2 MB
DOS Configuration Tool v1.00.0272008-07-22 For MS-DOS Legacy I/O Ports Configuration388.8 KB


click here for more MCS9845 FAQs....
Q0001: Where can I obtain the latest MCS9845/MCS9835/MCS9820/MCS9815/MCS9805 datasheet, reference schematic and other hardware design archives?
A0001: Please register MyASIX membership ( and then download the latest MCS9845/MCS9835/MCS9820/MCS9815/MCS9805 datasheet, reference schematic, PCB layout guide, etc. from ASIX I/O Connectivity Product web pages ( directly.

Q0002: Can ASIX help me to review my own MCS98xx schematic and PCB layout?
A0002: Yes, please deliver your own MCS98xx schematic and PCB layout files to ASIX's Support ( for further review before making your own MCS98xx PCB board.

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