AMD

2-158

PALCE20V8 Family

FUNCTIONAL DESCRIPTION

The PALCE20V8 is a universal PAL device. It has eight

Each macrocell can be configured as a registered out-

put, combinatorial output, combinatorial I/O, or dedi-

cated input. The programming matrix implements a

programmable AND logic array, which drives a fixed OR

logic array. Buffers for device inputs have complemen-

tary outputs to provide user-programmable input signal

polarity. Pins 1 and 13 serve either as array inputs or as

clock (CLK) and output enable (

OE) for all flip-flops.

Product terms with all bits unprogrammed (discon-

nected) assume the logical HIGH state and product

terms with both true and complement of any input signal

connected assume a logical LOW state.

The programmable functions on the PALCE20V8 are

automatically configured from the user’s design specifi-

cation, which can be in a number of formats. The design

specification is processed by development software to

verify the design and create a programming file. This

file, once downloaded to a programmer, configures the

device according to the user’s desired function.

The user is given two design options with the

PALCE20V8. First, it can be programmed as an emu-

lated PAL device. This includes the PAL20R8 series

and most 24-pin combinatorial PAL devices. The PAL

device programmer manufacturer will supply device

codes for the standard PAL architectures to be used

with the PALCE20V8. The programmer will program the

PALCE20V8 to the corresponding PAL device architec-

ture. This allows the user to use existing standard PAL

device JEDEC files without making any changes to

them. Alternatively, the device can be programmed

directly as a PALCE20V8. Here the user must use the

PALCE20V8 device code. This option provides full utili-

zation of the macrocells, allowing non-standard archi-

tectures to be built.

16491D-4

11

0X

10

11

10

00

01

11

10

0X

10

0X

11

SG1

CLK

OE

To

Adjacent

Macrocell

From

Adjacent

Pin

*SG1

DQ

Q

Figure 1. PALCE20V8 Macrocell