PALCE16V8 and PALCE16V8Z Families

3

Alternatively, the device can be programmed as a PALCE16V8. Here the user must use the

PALCE16V8 device code. This option allows full utilization of the macrocell.

CONFIGURATION OPTIONS

Each macrocell can be configured as one of the following: registered output, combinatorial

output, combinatorial I/O, or dedicated input. In the registered output configuration, the output

buffer is enabled by the OE pin. In the combinatorial configuration, the buffer is either controlled

by a product term or always enabled. In the dedicated input configuration, it is always disabled.

(CLK).

The macrocell configurations are controlled by the configuration control word. It contains 2

determines whether registers will be allowed. SG1 determines whether the PALCE16V8 will

either active low or active high for the individual macrocell.

The configuration bits work by acting as control inputs for the multiplexers in the macrocell.

There are four multiplexers: a product term input, an enable select, an output select, and a

Figure 1. PALCE16V8 Macrocell

1 1

0 X

1 0

*SG1

SG1

DQ

Q

1 0

1 1

0 X

1 1

1 0

0 0

0 1

CLK

OE

To

Adjacent

Macrocell

From

Adjacent

Pin

1 1

0 X

1 0

16493E-2