ATF16V8B
6
Electronic Signature Word
There are 64 bits of programmable memory that are always
available to the user, even if the device is secured. These
bits can be used for user-specific data.
Programming/Erasing
Programming/erasing is performed using standard PLD
programmers. See
CMOS PLD Programming Hardware
and Software Suppor
t for information on software/program-
ming.
Input and I/O Pull-Ups
All ATF16V8B family members have internal input and I/O
pull-up resistors. Therefore, whenever inputs or I/Os are
not being driven externally, they will float to V
CC
. This
ensures that all logi c array inputs are at kn own states.
These are relatively weak active pull-ups that can easily be
overdriven by TTL-compatible driver s (see input and I/O
diagrams below).
Input Diagram I/O Diagram
Functional Logic Diagram Description
The Logic Option and Fu nctional Diagrams des cribe the
ATF16V8B architec ture. Eig ht configur able ma crocell s can
be configured as a registered output, combinatorial I/O,
combinatorial output, or dedicated input.
The ATF16V8B can b e conf igured in one o f three dif feren t
modes. Each mode makes the ATF16V8B look like a different device. Most PLD compilers can choose the right
mode automatically. The user can also force the selection
by supplying the compiler with a mode selection. The determining factors would be the usage of register versus combinatorial ou tputs and dedic ated output s versus outpu ts
with output enable control.
The ATF16V8B universal architectur e can be pro grammed
to emulate many 20-pin PAL devi ces. The se architectu ral
subsets can be found in eac h of the con figuratio n modes
described in the foll owing pages. The user can downl oad
the listed sub set device JEDEC progr amming fil e to the
PLD programmer, and the ATF16V8 B c an be c onfigu re d to
act like the chosen device. Check with your programmer
manufacturer for this capability.
Unused product terms a re automatic ally disabled by the
compiler to decrease power consumption. A Security Fuse,
when programmed, protects the cont ent of the ATF16V8B .
Eight bytes (64 fuses) of User Signature are accessible to
the user for purposes such as storing project name, part
number, revision, or date. The User Signature is accessible
regardless of the state of the Security Fuse.
Note: 1. Only applicable for version 3.4 or lower.
Compiler Mode Selection
Registered Complex Simple Auto Select
ABEL, Atmel-ABEL
P16V8R P16V8C P16V8AS P16V8
CUPL
G16V8MS G16V8MA G16V8AS G16V8
LOG/iC
GAL16V8_R
(1)
GAL16V8_C7
(1)
GAL16V8_C8
(1)
GAL16V8
OrCAD-PLD
“Registered” “Com pl ex” “Simple” GAL16V8A
PLDesigner
P16V8R P16V8C P16V8C P16V8A
Tango-PLD
G16V8R G16V8C G16V8AS G16V8