Rainbow Electronics ATF16V8BQL - Manual (Page 7)

ATF16V8B(QL)
7
Macrocell Configuration
Software compilers support the three different OMC
modes as different device types. 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 software 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 combina-
torial without OE control. The different device types can be
used to override the automatic device selection by the soft-
ware. 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 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 combinato-
rial output.
ATF16V8B Registered Mode
PAL Device Emulation/PAL Replacement. The registered
mode is used if one or more registers are required. Each
macrocell can be configured as either a registered or com-
binatorial output or I/O, or as an input. For a registered
output or I/O, the output is enabled by the OE pin, and the
register is clocked by the CLK pin. Eight product terms are
allocated to the sum term. For a combinatorial output or
I/O, the output enable is controlled by a product term, and
seven product terms are allocated to the sum term. When
the macrocell is configured as an input, the output enable is
permanently disabled.
Any register usage will make the compiler select this mode.
The following registered devices can be emulated using
this mode:
16R8 16RP8
16R6 16RP6
16R4 16RP4
Registered Configuration for
Registered Mode
(1)(2)
Notes: 1. Pin 1 controls common CLK for the registered out-
puts. Pin 11 controls common OE for the registered
outputs. Pin 1 and Pin 11 are permanently
configured as CLK and OE.
2. The development software configures all the archi-
tecture control bits and checks for proper pin usage
automatically.
Combinatorial Configuration for
Registered Mode
(1)(2)
Notes: 1. Pin 1 and Pin 11 are permanently configured as CLK
and OE.
2. The development software configures all the archi-
tecture control bits and checks for proper pin usage
automatically.