10 ns EE PLD in a through-hole DIP
The Microchip ATF16V8BQ-10PC is an electrically erasable programmable logic device (EE PLD) from the 16V8 family, offering 8 macrocells and a 10 ns propagation delay. It operates from a single 5V supply and is housed in a 20-pin DIP (0.300" body width) — the same footprint as the industry-standard 20L8/PALCE16V8.
The 10 ns propagation delay (tPD) sets the timing budget for address decoding, chip-select generation, and state-machine logic. In a system with a 50 MHz clock (20 ns period), a 10 ns PLD leaves only 10 ns for the rest of the path — so this part is best suited for sub-50 MHz designs or for non-critical combinatorial paths where the extra margin is welcome. If your bus runs faster, you'll want a 7.5 ns or 5 ns variant in the same family.
EE reprogrammability and the 8-macrocell ceiling
Being electrically erasable (EE PLD), this chip can be reprogrammed in-circuit or on a programmer without a UV eraser — a real advantage during prototyping and field updates. The 8 macrocells can each be configured as registered or combinatorial outputs, giving you up to 8 flip-flops or 8 sum-of-products terms. That's enough for a 3-to-8 decoder, a small state machine, or a handful of address comparators, but not for a full 16-bit counter or a complex sequencer.
Microchip lists the ATF16V8BQ-10PC as obsolete. If you are designing a new board, consider the ATF16V8B-10PU (the lead-free, still-active PLCC/SOIC variant) or a CPLD from the ATF150x family for a drop-in logic upgrade.