The W78C438B is a high-performance single-chip CMOS 8-bit microcontroller that is a derivative of the W78C58 microcontroller family. The W78C438B is functionally compatible with the W78C32, except that it provides either a 64 KB program/1 MB data memory address or memory-mapped chip select logic, five general I/O ports, and four external interrupts.
The W78C438B is a derivative of the W78C58 family and is functionally compatible with the W78C32, offering expanded memory options, five general‑purpose I/O ports, a parallel port, and four external interrupts. It operates from 0 °C to 70 °C and supports both idle and power‑down modes for low‑power applications.
Key features include a fully static design, DC to 40 MHz operation, 256‑byte on‑chip RAM, up to 64 KB program/1 MB data memory space, three 16‑bit timers, a full‑duplex serial channel, and selectable 84‑pin PLCC or 100‑pin PQFP packages.
| Operating Speed | DC to 40 MHz |
|---|---|
| On‑chip RAM | 256‑byte scratchpad |
| Program / Data Memory | 64 KB program / 1 MB data |
| Package Options | 84‑pin PLCC, 100‑pin PQFP |
| Supply Voltage | VDD‑VSS -0.3 V to +7.0 V |
The HB register holds the high byte of the external address for paging and its contents are output to AP6 during a MOVX @Ri operation.
It provides four external interrupts (INT0‑INT3).