VersaLogic VL-12CT96, Reference Manual

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VL-12CT96/7 Analog & Digital I/O Card
2-7
IOEXP Signal
The IOEXP (I/O expansion) signal on the STD Bus is normally used to select between two different I/
O banks or maps. It can be used to double the number of available I/O addresses in the system (by
selecting between two banks of I/O boards). The IOEXP signal is usually controlled by (or jumpered
to ground on) the system CPU card.
A low IOEXP signal usually selects the standard or normal I/O map. A high IOEXP signal usually
selects the secondary or alternate I/O map. Boards that ignore (or do not decode) IOEXP will appear
in both I/O maps.
As shipped the IOEXP jumper is configured to ignore the IOEXP signal. The board will be addressed
whether the IOEXP signal is high or low. It can be jumpered for two other modes as shown below.
Jumper Jumper
Jumper Jumper
Jumper As As
As As
As
Block Block Block Block Block Description Description Description Description Description Shipped Shipped Shipped Shipped Shipped
V10 IOEXP Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IOEXP Ignored
[1-2] = In – Board responds to IOEXP high and low (IOEXP ignored)
[2-3] = In – Board responds to IOEXP low
[Both] = Out – Board responds to IOEXP high
Figure 2-5. IOEXP Options
Data Bus Width
The VL-12CT96/7 provides both 8-bit and 16-bit data paths to the bus. The 8-bit mode is compatible
with STD 80, STD Z80, and STD 32 bus specifications. The 16-bit mode is used only when operating
the card in an STD 32 card cage.
In 8-bit mode, the register map for the VL-12CT96/7 is a superset of the Analog Devices RTI-1265 board.
In 16-bit mode, the registers are remapped to even addresses for efficient I/O access. This allows the
full A/D data word to be read in a single bus cycle. See the I/O Port Mapping section on page 4-1 for
further information.
Jumper Jumper Jumper Jumper Jumper As As As As As
Block Block
Block Block
Block Description Description
Description Description
Description Shipped Shipped
Shipped Shipped
Shipped
V8[1-2] Data Bus Width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-Bit
In – 8-Bit Data Bus
Out – 16-Bit Data Bus
Figure 2-14. Data Bus Width Jumper
Configuration — Board Addressing/Data Bus Width