Specifications GAL16V8
3
The following discussion pertains to configuring the output logic
macrocell. It should be noted that actual implementation is accom-
plished by development software/hardware and is completely trans-
parent 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 individ-
ual 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 software will trans-
parently 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 GAL16V8
Emulated by GAL16V8 Global OLMC Mode
16R8 Registered
16R6 Registered
16R4 Registered
16RP8 Registered
16RP6 Registered
16RP4 Registered
16L8 Complex
16H8 Complex
16P8 Complex
10L8 Simple
12L6 Simple
14L4 Simple
16L2 Simple
10H8 Simple
12H6 Simple
14H4 Simple
16H2 Simple
10P8 Simple
12P6 Simple
14P4 Simple
16P2 Simple
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 automatically select the
device type, generally based on the register usage and output
enable (OE) usage. Register usage on the device forces the soft-
ware to choose the registered mode. All combinatorial 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.
In registered mode pin 1 and pin 11 are permanently configured
as clock and output enable, respectively. These pins cannot be con-
figured 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.
Registered Complex Simple Auto Mode Select
ABEL P16V8R P16V8C P16V8AS P16V8
CUPL G16V8MS G16V8MA G16V8AS G16V8
LOG/iC GAL16V8_R GAL16V8_C7 GAL16V8_C8 GAL16V8
OrCAD-PLD "Registered"
1
"Complex"
1
"Simple"
1
GAL16V8A
PLDesigner P16V8R
2
P16V8C
2
P16V8C
2
P16V8A
TANGO-PLD G16V8R G16V8C G16V8AS
3
G16V8
1) Used with Configuration keyword.
2) Prior to Version 2.0 support.
3) Supported on Version 1.20 or later.
Output Logic Macrocell (OLMC)
Compiler Support for OLMC
