Z86C97-ROMLESS

The Z86C27 and Z86C97 Digital Television Controller (DTC) introduce a new level of sophistication to single-chip architecture. The Z86C27/C97 are members of the Z8 single-chip microcontroller family with 8 Kbytes of ROM (Z86C27), ROMless (Z86C97) and 236 bytes of RAM. Both devices are housed in a 64-pin DIP package, and are CMOS compatible. Having the ROM/ROMless selectivity, the DTC offers both external memory and pre-programmed ROM which enables the Z8 microcontroller to be used in a high volume production application device embedded with a custom program (customer supplied program). The Z86C97 ROMless offers the use of external memory rather than a preprogrammed ROM. This enables the Z8 microcontroller to be used in prototyping, low volume applications or where code flexibility is required. Zilog's DTC offers fast execution, efficient use of memory, sophisticated interrupts, input/output bit manipulation capabilities, and easy hardware/software system expansion along with low cost and low power consumption. The device provides an ideal performance and reliability solution for consumer and industrial television applications.

The Z86C27/C97 architecture is characterized by utilizing Zilog's advanced Superintegration™ design methodology. The devices have an 8-bit internal data path controlled by a Z8 microcontroller, and On Screen Display (OSD) logic circuits/Pulse Width Modulators (PWM). Onchip peripherals include two register mapped I/O ports (Ports 2 and Port 3), Interrupt control logic (1 software, 2 external and 3 internal interrupts) and a standby mode recovery input port (Port 3, pin P30).

The OSD control circuits support 8 rows by 20 columns for 128 kinds of characters. The character color is specified by row. One of the 8 rows is assigned to show two kinds of colors for bar type displays such as volume control. The OSD is capable of displaying either low resolution (5x7 dot pattern) or high resolution (11x15 dot pattern) characters. The Z86C97 currently supports high resolution characters only.

A 14-bit PWM port provides enough voltage resolution for a voltage synthesizer tuning system. Seven 6-bit PWM ports are used for controlling audio signal level. Five 8-bit PWM ports are used to vary picture levels.

The DTC applications demand powerful I/O capabilities. The Z86C27/C97 fulfills this with 35 I/O pins dedicated to input and output. These lines are grouped into five ports, and are configurable under software control to provide timing, status signals, parallel I/O and an address/data bus for interfacing to external memory.

There are three basic address spaces available to support this wide range of configurations: Program Memory, Register File and Data Memory. The Register File is composed of 236 bytes of general purpose register, two I/O Port registers and 15 control and status registers.

To unburden the program from coping with the real-time problems such as counting/timing and data communication, the DTC's offer two on-chip counter/timers with a large number of user selectable modes (see block diagram).

Note: All Signals with a preceding front slash, "/", are active Low, e.g.: B//W (WORD is active Low); /B/W (BYTE is active Low, only).