9323 Hamilton Drive

Mentor, Ohio 44060




Scientific Solutions ®Inc.,

BaseBoard ® / ISA

Product Description

Our Solution Includes

Key Features


Functional Description

Technical Specifications

The BaseBoard / ISA provides flexible, programmable Digital Input / Output for the ISA computer. 96 lines of TTL compatible I/O are distributed on four 40 pin header connectors across one full size PC board.

Optional plug in opto-isolation boards provide both over-voltage protection, buffer/driver capabilities, and increased voltage handling above the +5v TTL levels.


arrow Product Description

The BaseBoard provides flexible, programmable digital input/output for the PC. 96 lines of TTL compatible Digital I/O (in sets of 24) are distributed on four 40-pin header connectors across one full size PC board. The BaseBoard has hardware interrupt capability when handshaking configurations are enabled. Optional plug in opto-isolation boards provide both over-voltage protection to +2500V and buffer/driver capability to +30V and +80mA.

arrow Our Solution Includes

arrow Key Features

arrow Applications

arrow Functional Description

The BaseBoard is an ISA board that installs internally into an expansion slot of a PC. Four 8255A Peripheral Port Interface (PPI) chips provide 96 lines of digital I/O. Each 8255A has a separate 40-pin header connector to carry the 24 digital I/O lines plus ground and power lines. This arrangement allows up to four plug-in opto-isolation boards to be used. Ribbon cables or screw terminal boards with cables are also available to ease interfacing to external signals.

arrow Digital Input/Output (DIO)

The Digital I/O signals of the BaseBoard are addressed in groups of 24 lines and can be programmed for a number of different configurations:

All outputs are latched. Simple input is unlatched while strobed input is latched. The 24 bits of digital I/O are programmed through four locations. One location is a command register to configure the 24 lines. The three data locations are contiguous in the I/O space.

The BaseBoard / ISA fully supports the following Digital I/O modes:

arrow Signal Conditioning Modules

The BaseBoard / ISA can accommodate the same signal conditioning modules as used with the BaseBoard / PCI. These modules plug directly onto internal connectors of the BaseBoard / ISA card internal to the computer.  The BaseBoard / ISA allows you to customize your setup by adding up to 4 modules of your choice. An unlimited array of modules can be created by the user including relay control, SCR, voltage control, etc.

Scientific Solutions offers multiple module options which are described on the following link:

Link to BaseBoard Modules

arrow Interrupts

Hardware interrupts allow the computer's processor to react to special events when they occur. The BaseBoard provides eight software enabled sources for hardware interrupts using a handshake signal of the strobed or bi-directional I/O modes. An 8-position switch block connects any combination of the eight strobe sources to a DIP jumper, where the combined signal is connected to one of six hardware interrupt request lines (IRQ2 to IRQ7). Once the hardware is connected, an interrupt is enabled by writing a command to the PPI Control Port. Hardware interrupts require special software called Interrupt Service Routines to process the interrupt.

System Resources

The BaseBoard / ISA occupies a single full size ISA slot in the computer. The connection from the computer to the outside world is thru a four ribbon cables that connect directly to the card in the computer and pass thru the special card bracket that secures the cables and provides strain relief.

The BaseBoard / ISA occupies 16 locations in the I/O space of the computer. The address of the card is configured using on-board switch settings.

Besides the Base Address I/O space, the BaseBoard / ISA can also use Interrupt resources of you computer. These resources are enabled and selected using jumpers on the card.  Note that your software has to be written to use interrupts.

If you are migrating your applications from ISA to PCI based computer, then you should consider the BaseBoard / PCI product from Scientific Solutions.

The BaseBoard / PCI provides 100% compatibility with the original ISA version. It adds features, but is a much smaller size for today's slim low-profile computers. The following picture compares the size of the original BaseBoard / ISA to the new BaseBoard / PCI card.

Comparing ISA to PCI card

Besides the size difference, a single BaseBoard / PCI card can accommodate from 96 up to 384 Digital I/O signals, has much higher electrical current sink/source handling capabilities, and incorporates Scientific Solutions exclusive Dynamic Digital Buffering (DDB TM) technology that assures maximum power in all operating modes!

arrow Technical Specifications

Digital Input/Output Characteristics
Number of bits
96 bits of Digital I/O per DeskTop Unit
(maximum of 384 bits per PCI card)
Programmable Modes
Full 8255 support
  • Mode0 - Basic I/O
  • Mode 1 - Strobed I/O
  • Mode 2 - Strobed Bi-Directional
Data Transfer
Programmed I/O
Logic Thresholds
Current Source 200 microamps
Current Sink 1.7 milliamps

Physical Characteristics
ISA Card
Dimensions (aprox.)
4.2" high x 13" long
(107mm x 330mm)
Data Connectors
40 pin header (standard)
50 pin header (opto modules)

System Resources

Bus Interface Single 8-bit or 16-bit ISA slot
IRQ Channels IRQ 2 -7, jumper selectable
Address 16 I/O locations Required
Any I/O Address, switch selectable
Bus Load 1 TTL load/bus line maximum

Environmental Specifications
Operating Temperature 0º to 70º Celsius
Storage Temperature -25º to +85º Celsius
Relative Humidity To 95% non-condensing
Agency Approvals Class A, CE-Mark