The W65C21S is a very flexible Peripheral Interface Adapter (PIA) for use with WDC’s 65xx and other 8-bit microprocessor families. It is produced by
Western Design Center (WDC).
The W65C21S provides programmed microprocessor control of up to two peripheral devices (Port A and Port B). Peripheral device control is accomplished through two 8-bit bidirectional
I/O Ports, with individually designed Data Direction Registers. The Data Direction Registers provide selection of data flow direction (input or output) at each respective I/O Port. Data flow direction may be selected on a line-by-line basis with intermixed input and output lines within the same port. The “handshake” interrupt control feature is provided by four peripheral control lines. This capability provides enhanced control over data transfer functions between the microprocessor and peripheral devices, as well as bidirectional data transfer between W65C21S
Peripheral Interface Adapter
A Peripheral Interface Adapter (PIA) is a peripheral integrated circuit providing parallel I/O interfacing for microprocessor systems.
Description
Common PIAs include the Motorola MC6820 and MC6821, and the MOS Technology MCS6520, all of w ...
s in multiprocessor systems.
The PIA interfaces to the 65xx microprocessor family with a reset line, a ϕ2 clock line, a read/write line, two interrupt request lines, two register select lines, three chip select lines and an 8-bit bidirectional data bus. The PIA interfaces to the peripheral devices with four interrupt/control lines and two 8-bit bidirectional buses.
The W65C21S PIA is organized into two independent sections referred to as the A Side and the B Side. Each section consists of Control Register (CRA, CRB), Data Direction Register (DDRA, DDRB), Output Register (ORA, ORB), Interrupt Status Control (ISCA, ISCB) and the buffers necessary to drive the Peripheral Interface buses. Data Bus Buffers (DBB) interface data from the two sections to the data bus, while the Date Input Register (DIR) interfaces data from the DBB to the PIA registers. Chip Select and RWB control circuitry interface to the processor bus control lines.
Features of the W65C21S
*Low power
CMOS
Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss", ) is a type of metal–oxide–semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOSFE ...
N-well silicon gate technology
*High speed/Low power replacement for
Motorola
Motorola, Inc. () was an American Multinational corporation, multinational telecommunications company based in Schaumburg, Illinois, United States. After having lost $4.3 billion from 2007 to 2009, the company split into two independent p ...
/
Rockwell /
AMI
AMI or Ami may refer to:
Arts, entertainment and media
*AMI-tv, a Canadian TV channel
**AMI-télé, the French-language version
* AMI-audio, a Canadian audio broadcast TV service
*''Ami Magazine'', an Orthodox Jewish news magazine
Businesses ...
/ *
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 mo ...
/ MOSTEK /
HITACHI
() is a Japanese multinational corporation, multinational Conglomerate (company), conglomerate corporation headquartered in Chiyoda, Tokyo, Japan. It is the parent company of the Hitachi Group (''Hitachi Gurūpu'') and had formed part of the Ni ...
/
ST Microelectronics
STMicroelectronics N.V. commonly referred as ST or STMicro is a Dutch multinational corporation and technology company of French-Italian origin headquartered in Plan-les-Ouates near Geneva, Switzerland and listed on the French stock market. ST ...
/
GTE
GTE Corporation, formerly General Telephone & Electronics Corporation (1955–1982), was the largest independent telephone company in the United States during the days of the Bell System. The company operated from 1926, with roots tracing furth ...
/
CMD 6520, 6521, 6820,
6821 PIA’s
*Two 8-bit bidirectional I/O ports with individual data direction control.
*Automatic “Handshake” control of data transfers
*Two interrupts (one for each port) with program control
*Static to 14 MHz operation, with high speed Port A, CA2 outputs.
*Industrial temperature range
*40 Pin Plastic Dip and 44 Pin Plastic PLCC versions
*5 volt ± 10% supply requirements
*Compatible with the
65xx and
68xx family of microprocessors
External links
W65C21S Datasheet
Input/output integrated circuits