The W78958B is an 8-bit emulation microcontroller that supports emulation for the Winbond W78C51 family of products. It is designed to support real-time emulation tools, such as in-circuit emulators (ICEs). It comes in two different types, standard and advanced, which support different functions of the W78C51 family. It can be operated in normal mode or emulation mode, with emulation mode providing direct access to special function registers, the program counter, and internal RAM. It also provides signals to facilitate ICE design.
The W78958B is an 8‑bit CMOS emulation microcontroller designed for real‑time (up to 40 MHz) in‑circuit emulators. It supports both standard and advanced types, providing direct access to SFRs, PC, and internal RAM in emulation mode.
Key features include 256‑byte on‑chip scratchpad RAM, three 16‑bit timer/counters, a full‑duplex serial channel, and up to 1 MB of program memory in the advanced type. The device is supplied in a 100‑pin PQFP package and offers multiple I/O configurations and switching signals for internal/external ROM access.
| Maximum emulation frequency | 40 MHz |
|---|---|
| Package type | 100‑pin PQFP |
| Program memory (standard) | 64 KB |
| Program memory (advanced) | 1 MB |
| Data memory (standard) | 64 KB |
| Data memory (advanced) | 1 MB |
| On‑chip scratchpad RAM | 256 bytes |
| Timer/counters | Three 16‑bit |
| Serial channel | One full‑duplex |
| I/O ports (standard) | Four 8‑bit bidirectional |
Emulation mode is entered by driving the ICESET pin high asynchronously.
The IPME (Internal Program Memory Enable) and ESEL (Emulation address space Select) signals are used for switching.
The device supports real‑time emulation up to 40 MHz.
It is supplied in a 100‑pin PQFP package.