MAX 9000 Programmable Logic Device Family Data Sheet
For registered functions, each macrocell register can be individually
programmed for D, T, JK, or SR operation with programmable clock
control. The flipflop can also be bypassed for combinatorial operation.
During design entry, the user specifies the desired register type; the
MAX+PLUS II software then selects the most efficient register operation
for each registered function to optimize resource utilization.
Each programmable register can be clocked in three different modes:
■
By either global clock signal. This mode achieves the fastest clock-to-
output performance.
By a global clock signal and enabled by an active-high clock enable.
This mode provides an enable on each flipflop while still achieving
the fast clock-to-output performance of the global clock.
By an array clock implemented with a product term. In this mode, the
flipflop can be clocked by signals from buried macrocells or I/O pins.
■
■
Two global clock signals are available. As shown in
Figure 2,
these global
clock signals can be the true or the complement of either of the global clock
pins (DIN1 and
DIN2).
Each register also supports asynchronous preset and clear functions. As
shown in
Figure 3,
the product-term select matrix allocates product terms
to control these operations. Although the product-term-driven preset and
clear inputs to registers are active high, active-low control can be obtained
by inverting the signal within the logic array. In addition, each register
clear function can be individually driven by the dedicated global clear pin
(DIN3). The global clear can be programmed for active-high or active-low
operation.
All MAX 9000 macrocells offer a dual-output structure that provides
independent register and combinatorial logic output within the same
macrocell. This function is implemented by a process called register
packing. When register packing is used, the product-term select matrix
allocates one product term to the D input of the register, while the
remaining product terms can be used to implement unrelated
combinatorial logic. Both the registered and the combinatorial output of
the macrocell can feed either the FastTrack Interconnect or the LAB local
array.
Altera Corporation
9
ALTERA [ ALTERA CORPORATION ]
