The W65C22 versatile

interface Interface or interfacing may refer to: Academic journals * ''Interface'' (journal), by the Electrochemical Society * '' Interface, Journal of Applied Linguistics'', now merged with ''ITL International Journal of Applied Linguistics'' * '' Int ...

adapter (VIA) is an input/output device for use with the 65xx series microprocessor family. Designed by the

Western Design Center The Western Design Center (WDC), located in Mesa, Arizona, is a company which develops intellectual property for, and licenses manufacture of, MOS Technology 65xx based microprocessors, microcontrollers (µCs), and related support devices. W ...

, the W65C22 is made in two versions, both of which are rated for 14 megahertz operation, and available in DIP-40 or PLCC-44 packages.W65C22 Versatile Interface Adapter (VIA)
/ref> *W65C22N: This device is fully compatible with the NMOS 6522 produced by

MOS Technology MOS Technology, Inc. ("MOS" being short for Metal Oxide Semiconductor), later known as CSG (Commodore Semiconductor Group) and GMT Microelectronics, was a semiconductor design and fabrication company based in Audubon, Pennsylvania. It is mos ...

and others, and includes current-limiting resistors on its output lines. The W65C22N has an

open-drain An open collector is a common type of output found on many integrated circuits (IC), which behaves like a switch that is either connected to ground or disconnected. Instead of outputting a signal of a specific voltage or current, the output sig ...

interrupt output (the pin) that is compatible with a

wired-OR A wired logic connection is a logic gate that implements boolean algebra (logic) using only passive components such as diodes and resistors. A wired logic connection can create an AND or an OR gate. The limitations are the inability to create a ...

interrupt circuit. Hence the DIP-40 version is a "drop-in" replacement for the NMOS part. *W65C22S: This device is fully software– and partially hardware–compatible with the NMOS part. The W65C22S' output is a

totem pole Totem poles ( hai, gyáaʼaang) are monumental carvings found in western Canada and the northwestern United States. They are a type of Northwest Coast art, consisting of poles, posts or pillars, carved with symbols or figures. They are usually ...

configuration, and thus cannot be directly connected to a wired-OR interrupt circuit. As with the NMOS 6522, the W65C22 includes functions for programmed control of two peripheral ports (ports A and B). Two program–controlled 8-bit bi-directional peripheral I/O ports allow direct interfacing between the microprocessor and selected peripheral units. Each port has input data latching capability. Two programmable data direction registers (A and B) allow selection of data direction (input or output) on an individual I/O line basis. Also provided are two programmable 16-bit interval timer/counters with latches. Timer 1 may be operated in a one-shot or free-run mode. In either mode, a timer can generate an

interrupt In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to ''interrupt'' currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted, ...

when it has counted down to zero. Timer 2 functions as an interval counter or a pulse counter. If operating as an interval counter, timer 2 is driven by the microprocessor's Ø2 clock source. As a pulse counter, timer 2 is triggered by an external pulse source on the chip's line. Serial data transfers are provided by a serial to parallel/parallel to serial shift register, with bit transfers synchronized with the Ø2 clock. Application versatility is further increased by various control registers, including an interrupt flag register, an interrupt enable register and two Function Control Registers.

Features

*Advanced CMOS process technology for low power consumption *Software compatible with NMOS 6522 devices *Two 8-bit, bi-directional peripheral I/O Ports *Two 16-bit programmable Interval Timer/Counters *Serial bi-directional peripheral

I/O Port Memory-mapped I/O (MMIO) and port-mapped I/O (PMIO) are two complementary methods of performing input/output (I/O) between the central processing unit (CPU) and peripheral devices in a computer. An alternative approach is using dedicated I/O pro ...

*Enhanced handshaking capabilities *Latched input/output registers on both I/O ports *Programmable data direction registers *TTL compatible I/O peripheral lines *Single 1.8V to 5V

power supply A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As a ...

*Bus compatible with high-speed W65C02S and W65C816S microprocessors *Register and chip selects specified for multiplexed operation *Totem pole output for reduced interrupt circuit latency (W65C22S version only)

References

External links

W65C22 Datasheet
from the

website {{MOS CPU Input/output integrated circuits

Features

See also

References

External links