Specifications
GAL16V8
OUTPUT LOGIC MACROCELL (OLMC)
The following discussion pertains to configuring the output logic
macrocell. It should be noted that actual implementation is ac-
complished by development software/hardware and is completely
transparent to the user.
There are three global OLMC configuration modes possible:
simple, complex,
and
registered.
Details of each of these
modes are illustrated in the following pages. Two global bits, SYN
and AC0, control the mode configuration for all macrocells. The
XOR bit of each macrocell controls the polarity of the output in any
of the three modes, while the AC1 bit of each of the macrocells
controls the input/output configuration. These two global and 16
individual architecture bits define all possible configurations in a
GAL16V8 . The information given on these architecture bits is
only to give a better understanding of the device. Compiler soft-
ware will transparently set these architecture bits from the pin
definitions, so the user should not need to directly manipulate
these architecture bits.
The following is a list of the PAL architectures that the GAL16V8
can emulate. It also shows the OLMC mode under which the
GAL16V8 emulates the PAL architecture.
PAL Architectures
Emulated by GAL16V8
16R8
16R6
16R4
16RP8
16RP6
16RP4
16L8
16H8
16P8
10L8
12L6
14L4
16L2
10H8
12H6
14H4
16H2
10P8
12P6
14P4
16P2
GAL16V8
Global OLMC Mode
Registered
Registered
Registered
Registered
Registered
Registered
Complex
Complex
Complex
Simple
Simple
Simple
Simple
Simple
Simple
Simple
Simple
Simple
Simple
Simple
Simple
COMPILER SUPPORT FOR OLMC
Software compilers support the three different global OLMC
modes as different device types. These device types are listed
in the table below. Most compilers have the ability to automati-
cally select the device type, generally based on the register usage
and output enable (OE) usage. Register usage on the device
forces the software to choose the registered mode. All combina-
torial outputs with OE controlled by the product term will force the
software to choose the complex mode. The software will choose
the simple mode only when all outputs are dedicated combinatorial
without OE control. The different device types listed in the table
can be used to override the automatic device selection by the
software. For further details, refer to the compiler software
manuals.
When using compiler software to configure the device, the user
must pay special attention to the following restrictions in each
mode.
Registered
ABEL
CUPL
LOG/iC
OrCAD-PLD
PLDesigner
TANGO-PLD
P16V8R
G16V8MS
GAL16V8_R
"Registered"
1
P16V8R
2
G16V8R
Complex
P16V8C
G16V8MA
GAL16V8_C7
"Complex"
1
P16V8C
2
G16V8C
Simple
P16V8AS
G16V8AS
GAL16V8_C8
"Simple"
1
P16V8C
2
G16V8AS
3
Auto Mode Select
P16V8
G16V8
GAL16V8
GAL16V8A
P16V8A
G16V8
In
registered mode
pin 1 and pin 11 are permanently configured
as clock and output enable, respectively. These pins cannot be
configured as dedicated inputs in the registered mode.
In
complex mode
pin 1 and pin 11 become dedicated inputs and
use the feedback paths of pin 19 and pin 12 respectively. Because
of this feedback path usage, pin 19 and pin 12 do not have the
feedback option in this mode.
In
simple mode
all feedback paths of the output pins are routed
via the adjacent pins. In doing so, the two inner most pins ( pins
15 and 16) will not have the feedback option as these pins are
always configured as dedicated combinatorial output.
1) Used with
Configuration
keyword.
2) Prior to Version 2.0 support.
3) Supported on Version 1.20 or later.
3-67
1996 Data Book
LATTICE [ LATTICE SEMICONDUCTOR ]
