GENERAL DESCRIPTION
The eight PAL blocks are essentially “PAL26V12” structures complete with product-term arrays, and programmable macrocells, including buried macrocells. The switch matrix connects the PAL blocks to each other and to all input pins, providing a high degree of connectivity between the fully-connected PAL blocks. This allows designs to be placed and routed efficiently. The MACH220 has two kinds of macrocell: output and buried. The output macrocell provides registered, latched, or combinatorial outputs with programmable polarity. If a registered configuration is chosen, the register can be configured as D-type or T-type to help reduce the number of product terms. The register type decision can be made by the designer or by the software. All output macrocells can be connected to an I/O cell. If a buried macrocell is desired, the internal feedback path from the macrocell can be used, which frees up the I/O pin for use as an input. The MACH220 has dedicated buried macrocell...
Lattice
