The W65C22S 8/16 bit Versatile Interface Adapter (VIA) is a flexible I/O device similar to the W65C21. In addition to I/O, the W65C22 provides two programmable 16–bit Interval Timer/Counters with latches and synchronous serial interface shift register. The W65C22 is available in both CMOS and NMOS compatible versions.
Features of the W65C22
- 2 x 8−bit, bi−directional peripheral I/O Ports
- 2 x 16−bit programmable Interval Timer/Counters
- Synchronous Serial bi−directional peripheral I/O Port
- Enhanced “Handshake” feature works with either 8− or 8/16−bit systems
- Latched Input/Output Registers on both I/O Ports
- Programmable Data Direction Registers
- TTL compatible I/O peripheral lines
- 1.8V(W65C22S only) − 5V Power Supply
- Bus compatible with 14 MHz W65C02S and W65C816S
- Compatible with the 65xx and 68xx family of microprocessors
- Replacement for Rockwell / GTE / CMD / Synertek / MO
• The W65C22S is lower power, faster and direct drive outputs with no current limiting resistors on outputs ports.
• The W65C22N is plug replacement of NMOS 6522 devices with current limiting resistors on output ports.
• The W65C22N does not have bus holding devices on the input, IO pins.
• The W65C22N IRQB is an open drain output that CAN be Wire-ORd, unlike the totem-pole output of the W65C22S (some customers have had to use a diode in series with the IRQB output when using the W65C22S in their systems that had Wire-ORd interrupts).
Interface Signals Relationship