Rainbow Electronics W78C438C - Manual

W78C438C
8-BIT MICROCONTROLLER
Publication Release Date: July 1998
- 1 - Revision A1
GENERAL DESCRIPTION
The W78C438C is a high-performance single-chip CMOS 8-bit microcontroller that is a derivative of
the W78C58 microcontroller family. The W78C438C 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.
In the W78C32, two I/O ports, Port 1 and Port 3, are available for general-purpose use (Port 3 also
supports alternative functions), and Port 2 and Port 0 are used as the address bus and data bus,
respectively. To enable Port 0 and Port 2 to also be used as general purpose I/O ports, the
W78C438C provides two dedicated address ports (AP5 and AP6) that serve as address output for 64
KB of memory and one address/data port (DP4) that serves as ROM code input and external RAM
data input/output. Unlike the W78C32, this product does not require an external latch device for
multiplexing low byte addresses. The W78C438C also provides four pins (AP7.0
−AP7.3) to support
either 64 KB program/1 MB data memory space or memory-mapped chip select logic, one parallel I/O
port (Port 8) without bit addressing mode, and two additional external interrupts ( INT2 , INT3 ) .
The W78C438C is programmed in a manner fully compatible with that used to program the W78C32,
except that the external data RAM is accessed by the "MOVX @Ri" instruction. Address paging is
performed by loading page addresses into the HB (high byte) register, which is not a standard register
in the W78C32, before execution of the "MOVX @Ri" instruction.
FEATURES
• 8-bit CMOS microcontroller
• Fully static design
• DC to 40 MHz operation
• ROM-less operation
• 256-byte on-chip scratchpad RAM
• Either 64 KB program/1 MB data memory address space or 4 memory-mapped chip select pins
• One 8-bit data/address port
• Two 8-bit and one 4-bit (optional) address ports
• Five 8-bit bidirectional I/O ports
− Four 8-bit bit-addressable I/O ports and one 8-bit parallel I/O port
• Eight-source, two-level interrupt capability
• Three 16-bit timer/counters
• Four external interrupts
• One full-duplex serial channel
• Built-in power management
− Idle mode
− Power-down mode
• Packages:
− 84-pin PLCC: W78C438CP-24/40
− 100-pin PQFP: W78C438CF-24/40