ZILOG Z86C6116FSC, Z86C6116PEC, Z86C6116PSC, Z86C6116VEC, Z86C6116VSC Datasheet

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Z86C61/62/96

MICROCONTROLLER

RODUCT

PECIFICATION

Z86C61/62/96

CMOS Z8

MICROCONTROLLER

FEATURES

■ 8-Bit CMOS Microcontroller

■ 40-Pin DIP, 44-Pin PLCC, 64-Pin DIP, or

68-Pin PLCC Package

■ 32 Input/Output Lines (Z86C61 Only)

■ 52 Input/Output Lines (Z86C62 and Z86C96)

■ 3.0V to 5.5V Operating Range

■ Low Power Consumption: 200 mW (max)

■ Fast Instruction Pointer: 0.75 µs @ 16 MHz

■ Two Standby Modes: STOP and HALT

■ Full-Duplex UART

■ All Digital Inputs are TTL Levels

GENERAL DESCRIPTION

The Z86C61/62/96 microcontroller is a member of the Z8

single-chip microcontroller family with 16 Kbytes of ROM

and 256 bytes of RAM. The Z86C96 is ROMless.

The Z86C61 is offered in 40-pin DIP and 44-pin PLCC style

packages, however, the ROMless pin option is available

on the 44-pin version only. The Z86C62/96 is offered in 64-

pin DIP and 68-pin PLCC style packages. A ROMless pin

option enables these MCUs to address both external

memory and preprogrammed ROM, making them well-

suited for high-volume applications or where code flexibil-

ity is required.

With 16 Kbytes of ROM and 256 bytes of general-purpose

RAM, these low-cost, low power consumption CMOS

Z86C61/62/96 MCUs offer fast execution, efficient use of

memory, sophisticated interrupts, input/output bit manipu-

lation capabilities, and easy hardware/software system

expansion.

The Z86C61/62/96 architecture is characterized by Zilog’s

8-bit microcontroller core. The device offers a flexible I/O

scheme, an efficient register and address space structure,

multiplexed capabilities between address/data, I/O, and a

number of ancillary features that are useful in many indus-

trial and advanced scientific applications.

For applications which demand powerful I/O capabilities,

the Z86C61 fulfills this with 32 pins dedicated to input and

output. These lines are grouped into four ports with eight

lines each. The Z86C62/96 has 52 pins for input and

output, and these lines are grouped into six, 8-bit ports and

one 4-bit port. Each port is configurable under software

control to provide timing, status signals, serial or parallel

I/O with or without handshake, and an address/data bus

for interfacing external memory.

■ Auto Latches

■ RAM and ROM Protect

■ 16 Kbytes of ROM

■ 256 Bytes of RAM

■ Two Programmable 8-Bit Counter/Timers,

Each with 6-Bit Programmable Prescaler

■ Six Vectored, Priority Interrupts from Eight

Different Sources

■ Clock Speeds: 16 and 20 MHz

■ On-Chip Oscillator that Accepts a Crystal,

Ceramic Resonator, LC, or External Clock Drive

Z86C61/62/96

MICROCONTROLLER

GENERAL DESCRIPTION (Continued)

There are three basic address spaces available to support

this configuration: Program Memory, Data Memory, and

236 General-Purpose Registers.

To unburden the program from coping with the real-time

tasks, such as counting/timing and serial data communi-

cation, the Z86C61/62/96 offers two on-chip counter/tim-

ers with a large number of user selectable modes, and an

on-board UART (Figures 1, 2, and 3).

Notes:

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).

Power connections follow conventional descriptions below:

Connection Circuit Device

Power V

Ground GND V

Port 3

UART

Counter/

Timers

(2)

Interrupt

Control

Port 2

I/O

(Bit Programmable)

ALU

FLAGS

Pointer

256 x 8-Bit

Machine Timing and

Instruction Control

Prg. Memory

16,384

x 8-Bit

Program

Counter

Vcc GND

XTAL

Port 0

Output Input

Address or I/O

(Nibble Programmable)

Port 1

Address/Data or I/O

(Byte Programmable)

/AS /DS R//W /RESET

Figure 1. Z86C61 Functional Block Diagram

Z86C61/62/96

MICROCONTROLLER

Port 3

Counter/

Timers (2)

Interrupt

Control

Port 2

ALU

Flags

Pointer

256 x 8-Bit

Machine Timing and

Instruction Control

Program

Counter

Vcc GND XTAL R//W /RESETOutput Input

UART

Port 0 Port 1

Address or I/O

(Nibble Programmable)

Address/Data or I/O

(Byte Programmable)

44 8

/AS /DS

Port 4Port 5Port 6

I/O

(Bit Programmable)

I/O

(Bit Programmable)

Program

Memory

16,384 x 8-Bit

Figure 2. Z86C62 Functional Block Diagram

Z86C61/62/96

MICROCONTROLLER

GENERAL DESCRIPTION (Continued)

Port 3

Counter/

Timers (2)

Interrupt

Control

Port 2

ALU

Flags

Pointer

256 x 8-Bit

Machine Timing and

Instruction Control

Program

Counter

Vcc GND XTAL R//W /RESETOutput Input

UART

Port 0 Port 1

Address or I/O

(Nibble Programmable)

Address/Data or I/O

(Byte Programmable)

44 8

/AS /DS

Z-BUS When Used

As Address/Data Bus

Port 4Port 5Port 6

I/O

(Bit Programmable)

Figure 3. Z86C96 Functional Block Diagram

Z86C61/62/96

MICROCONTROLLER

PIN DESCRIPTION

Table 1. Z86C61 40-Pin DIP Pin Identification

Pin # Symbol Function Direction

Power Supply Input

2 XTAL2 Crystal, Oscillator Clock Output

3 XTAL1 Crystal, Oscillator Clock Input

4 P37 Port 3, Pin 7 Output

5 P30 Port 3, Pin 0 Input

6 /RESET Reset Input

7 R//W Read/Write Output

8 /DS Data Strobe Output

9 /AS Address Strobe Output

10 P35 Port 3, Pin 5 Output

11 GND Ground Input

12 P32 Port 3, Pin 2 Input

13-20 P07-P00 Port 0, Pins 0,1,2,3,4,5,6,7 In/Output

21-28 P17-P10 Port 1, Pins 0,1,2,3,4,5,6,7 In/Output

29 P34 Port 3, Pin 4 Output

30 P33 Port 3, Pin 3 Input

31-38 P27-P20 Port 2, Pins 0,1,2,3,4,5,6,7 In/Output

39 P31 Port 3, Pin 1 Input

40 P36 Port 3, Pin 6 Output

P36

P31

P21

P27

P26

P25

P24

P23

P22

VCC

XTAL2

P37

P30

/RESE

R//W

/DS

2714

XTAL1

GND

P32

P00

P01

P20

P33

P34

P17

P16

Z86C61

DIP

/AS

P35

P02

P03

P06

P07

P05

P04 P13

P15

P14

P12

P11

P10

Figure 4. Z86C61 40-Pin DIP

Pin Assignments

Z86C61/62/96

MICROCONTROLLER

PIN DESCRIPTION (Continued)

N/C

P30

P37

XTAL1

XTAL2

VCC

P36

P31

P27

P26

P25

P03

P04

P05

P06

P07

P10

P11

P12

P13

P14

N/C

P24

P23

P22

P21

P20

P33

P34

P17

P16

P15

/RESET

R//W

/DS

/AS

P35

GND

P32

P00

P01

P02

R//RL

Z86C61

PLCC

6543214443424140

18 19 20 21 22 23 24 25 26 27 28

Figure 5. Z86C61 44-Pin PLCC Pin Assignments

Pin # Symbol Function Direction

Power Supply Input

2 XTAL2 Crystal, Oscillator Clock Output

3 XTAL1 Crystal, Oscillator Clock Input

4 P37 Port 3, Pin 7 Output

5 P30 Port 3, Pin 0 Input

6 N/C Not Connected Input

7 /RESET Reset Input

8 R//W Read/Write Output

9 /DS Data Strobe Output

10 /AS Address Strobe Output

11 P35 Port 3, Pin 5 Output

12 GND Ground Input

13 P32 Port 3, Pin 2 Input

14-16 P02-P00 Port 0, Pins 0,1,2 In/Output

Pin # Symbol Function Direction

17 R//RL ROM/ROMless control Input

18-22 P07-P03 Port 0, Pins 3,4,5,6,7 In/Output

23-27 P14-P10 Port 1, Pins 0,1,2,3,4 In/Output

28 N/C Not Connected Input

29-31 P17-P15 Port 1, Pins 5,6,7 In/Output

32 P34 Port 3, Pin 4 Output

33 P33 Port 3, Pin 3 Input

34-38 P24-P20 Port 2, Pins 0,1,2,3,4 In/Output

39 N/C Not Connected Input

40-42 P25-P27 Port 2, Pins 5,6,7 In/Output

43 P31 Port 3, Pin 1 Input

44 P36 Port 3, Pin 6 Output

Table 2. Z86C61 44-Pin PLCC Pin Identification

Z86C61/62/96

MICROCONTROLLER

P44

VCC

P45

XTAL2

P47

/AS

P35

R//RL

GND

P32

P50

P51

P43

P42

P36

P31

P41

P40

P27

P26

P25

P24

P23

P22

P60

P61

P21

P20

GND

P33

P34

P62

XTAL1

P37

P30

N/C

/RESET

R//W

/DS

P46

Z86C62

DIP

P00

P01

P02

P03

P63

P17

P16

P15

P06

P07

VCC

P52

P53

P54

P14

P13

P12

P57

P56

P11

P10

P55

P04

P05

Figure 6. Z86C62 64-Pin DIP Pin Assignments

Table 3. Z86C62 64-Pin DIP Pin Identification

Pin # Symbol Function Direction

1 P44 Port 4, Pin 4 In/Output

Power Supply Input

3 P45 Port 4, Pin 5 In/Output

4 XTAL2 Crystal, Oscillator Clock Output

5 XTAL1 Crystal, Oscillator Clock Input

6 P37 Port 3, Pin 7 Output

7 P30 Port 3, Pin 0 Input

8 N/C Not Connected Input

9 /RESET Reset Input

10 R//W Read/Write Output

11 /DS Data Strobe Output

12-13 P47-P46 Port 4, Pin 6,7 In/Output

14 /AS Address Strobe Output

15 P35 Port 3, Pin 5 Output

16 R//RL ROM/ROMless control Input

17 GND Ground Input

18 P32 Port 3, Pin 2 Input

19-20 P51-P50 Port 5, Pin 0,1 In/Output

21-28 P07-P00 Port 0, Pins 0,1,2,3,4,5,6,7 In/Output

29 V

Power Supply Input

30-33 P52-P55 Port 5, Pins 2,3,4,5 In/Output

34-35 P11-P10 Port 1, Pins 0,1 In/Output

36-37 P57-P56 Port 5, Pins 6,7 In/Output

38-43 P17-P12 Port 1, Pins 2,3,4,5,6,7 In/Output

44-45 P63-P62 Port 6, Pins 3,2 In/Output

46 P34 Port 3, Pin 4 Output

47 P33 Port 3, Pin 3 Input

48 GND Ground Input

49-50 P21-P20 Port 2, Pins 0,1 In/Output

51-52 P61-P60 Port 6, Pins 1,0 In/Output

53-58 P27-P22 Port 2, Pins 2,3,4,5,6,7 In/Output

59-60 P41-P40 Port 4, Pins 0,1 In/Output

61 P31 Port 3, Pin 1 Input

62 P36 Port 3, Pin 6 Output

63 P42 Port 4, Pin 2 In/Output

64 P43 Port 4, Pin 3 In/Output

Z86C61/62/96

MICROCONTROLLER

PIN DESCRIPTION (Continued)

Z86C62

PLCC

27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

/Reset

P30

P37

XTAL1

XTAL2

P45

VCC

P44

P43

P42

P36

P31

P41

P40

P26

P25

P27

P54

VCC

P07

P14

P13

P12

P57

P56

P11

P10

P55

P53

P52

P06

P04

P03

P05

789 6543216867666564636261

P24

P23

P22

P60

P61

P21

P20

SCLK

/SYNC

GND

P33

P34

P62

P63

P17

P16

P15

R//W

/P0DS

/DS

P46

P47

/P1DS

/AS

/DTimers

P35

R//RL

GND

P32

P50

P51

P00

P01

P02

Figure 7. Z86C62 68-Pin PLCC Pin Assignments

Z86C61/62/96

MICROCONTROLLER

Table 4. Z86C62 68-Pin PLCC Pin Identification

Pin # Symbol Function Direction

1-2 P44-P43 Port 4, Pins 3,4 In/Output

Power Supply Input

4 P45 Port 4, Pin 5 In/Output

5 XTAL2 Crystal, Oscillator Clock Output

6 XTAL1 Crystal, Oscillator Clock Input

7 P37 Port 3, Pin 7 Output

8 P30 Port 3, Pin 0 Input

9 /RESET Reset Input

10 R//W Read/Write Output

11 /P0DS Port 0 Data Strobe Output

12 /DS Data Strobe Output

13-14 P47-P46 Port 4, Pins 6,7 In/Output

15 /P1DS Port 1, Data Strobe Output

16 /AS Address Strobe Output

17 /DTIMER DTIMER Input

18 P35 Port 3, Pin 5 Output

19 R//RL ROM/ROMless control Input

20 GND Ground Input

21 P32 Port 3, Pin 2 Input

22-23 P51-P50 Port 5, Pins 0,1 In/Output

Pin # Symbol Function Direction

24-31 P07-P00 Port 0, Pins 0,1,2,3,4,5,6,7 In/Output

32 V

Power Supply Input

33-36 P55-P52 Port 5, Pins 2,3,4,5 In/Output

37-38 P11-P10 Port 1, Pins 0,1 In/Output

39-40 P56-P57 Port 5, Pins 6,7 In/Output

41-46 P17-P12 Port 1, Pins 2,3,4,5,6,7 In/Output

47-48 P63-P62 Port 6, Pins 3,2 In/Output

49 P34 Port 3, Pin 4 Output

50 P33 Port 3, Pin 3 Input

51 GND Ground Input

52 /SYNC Synchronization Output

53 SCLK System Clock Output

54-55 P21-P20 Port 2, Pins 0,1 In/Output

56-57 P60-P61 Port 6, Pins 1,0 In/Output

58-63 P27-P22 Port 2, Pins 2,3,4,5,6,7 In/Output

64-65 P41-P40 Port 4, Pins 0,1 In/Output

66 P31 Port 3, Pin 1 Input

67 P36 Port 3, Pin 6 Output

68 P42 Port 4, Pin 2 In/Output

Z86C61/62/96

MICROCONTROLLER

PIN DESCRIPTION (Continued)

Table 5. Z86C96 64-Pin DIP Pin Identification

Pin # Symbol Function Direction

1 P44 Port 4, Pin 4 In/Output

Power Supply Input

3 P45 Port 4, Pin 5 In/Output

4 XTAL2 Crystal, Oscillator Clock Output

5 XTAL1 Crystal, Oscillator Clock Input

6 P37 Port 3, Pin 7 Output

7 P30 Port 3, Pin 0 Input

8 N/C Not Connected Input

9 /RESET Reset Input

10 R//W Read/Write Output

11 /DS Data Strobe Output

12-13 P47-P46 Port 4, Pins 6,7 In/Output

14 /AS Address Strobe Output

15 P35 Port 3, Pin 5 Output

16 N/C Not Connected Input

17 GND Ground Input

18 P32 Port 3, Pin 2 Input

19-20 P51-P50 Port 5, Pins 0,1 In/Output

21-28 P07-P00 Port 0, Pins 0,1,2,3,4,5,6,7 In/Output

29 V

Power Supply Input

30-33 P55-P52 Port 5, Pins 2,3,4,5 In/Output

34-35 P11-P10 Port 1, Pins 0,1 In/Output

36-37 P56-P57 Port 5, Pins 6,7 In/Output

38-43 P17-P12 Port 1, Pins 2,3,4,5,6,7 In/Output

44-45 P63-P62 Port 6, Pins 3,2 In/Output

46 P34 Port 3, Pin 4 Output

47 P33 Port 3, Pin 3 Input

48 GND Ground Input

49-50 P21-P20 Port 2, Pins 0,1 In/Output

51-52 P61-P60 Port 6, Pins 1,0 In/Output

53-58 P27-P22 Port 2, Pins 2,3,4,5,6,7 In/Output

59-60 P41-P40 Port 4, Pins 0,1 In/Output

61 P31 Port 3, Pin 1 Input

62 P36 Port 3, Pin 6 Output

63 P42 Port 4, Pin 2 In/Output

64 P43 Port 4, Pin 3 In/Output

Z86C96

DIP

P43

P42

P36

P31

P41

P40

P27

P26

P25

P24

P23

P22

P60

P61

P21

P20

GND

P33

P34

P62

P63

P17

P16

P15

P14

P13

P12

P57

P56

P11

P10

P55

P44

VCC

P45

XTAL2

P47

/AS

P35

N/C

GND

P32

P50

P51

XTAL1

P37

P30

/RESET

R//W

/DS

P46

P00

P01

P02

P03

P06

P07

VCC

P52

P53

P54

P04

P05

Figure 8. Z86C96 64-Pin DIP Pin Assignments

Z86C61/62/96

MICROCONTROLLER

Z86C96

PLCC

789

654321

68 67 66 65 64 63 62 61

27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

/RESET

P30

P37

XTAL1

XTAL2

P45

VCC

P44

P43

P42

P36

P31

P41

P40

P26

P25

P27

P54

VCC

P07

P14

P13

P12

P57

P56

P11

P10

P55

P53

P52

P06

P04

P03

P05

P24

P23

P22

P60

P61

P21

P20

SCLK

/SYNC

GND

P33

P34

P62

P63

P17

P16

P15

R//W

/P0DS

/DS

P46

P47

/P1DS

/AS

/DTimers

P35

N/C

GND

P32

P50

P51

P00

P01

P02

Figure 9. Z86C96 68-Pin PLCC Pin Assignments

Z86C61/62/96

MICROCONTROLLER

PIN DESCRIPTION (Continued)

Table 6. Z86C96 68-Pin PLCC Pin Identification

Pin # Symbol Function Direction

1-2 P44-P43 Port 4, Pins 3,4 In/Output

Power Supply Input

4 P45 Port 4, Pin 5 In/Output

5 XTAL2 Crystal, Oscillator Clock Output

6 XTAL1 Crystal, Oscillator Clock Input

7 P37 Port 3, Pin 7 Output

8 P30 Port 3, Pin 0 Input

9 /RESET Reset Input

10 R//W Read/Write Output

11 /P0DS Port 0 Data Strobe Output

12 /DS Data Strobe Output

13-14 P47-P46 Port 4, Pins 6,7 In/Output

15 /P1DS Port 1 Data Strobe Output

16 /AS Address Strobe Output

17 /DTIMER Disable Timers Input

18 P35 Port 3, Pin 5 Output

19 N/C Not Connected Input

20 GND Ground Input

21 P32 Port 3, Pin 2 Input

22-23 P51-P50 Port 5, Pins 0,1 In/Output

PIN FUNCTIONS

XTAL1, XTAL2

Crystal 1, Crystal 2

(time-based input and

output, respectively). These pins connect a parallel-

resonant crystal, ceramic resonator, LC, or any external

single-phase clock to the on-chip oscillator and buffer.

R//W (output, write Low). The Read/Write signal is Low

when the MCU is writing to the external program or data

memory.

/RESET (input, active Low). To avoid asynchronous and

noisy reset problems, the Z86C61/62/96 is equipped with

a reset filter of four external clocks (4TpC). If the external

/RESET signal is less than 4TpC in duration, no reset

occurs.

On the fifth clock after the /RESET is detected, an internal

RST signal is latched and held for an internal register count

of 18 external clocks, or for the duration of the external

/RESET, whichever is longer. During the reset cycle, /DS is

held active Low while /AS cycles at a rate of TpC/2. When

/RESET is deactivated, program execution begins at loca-

tion 000C (HEX). Reset time must be held Low for 50 ms,

or until V

is stable, whichever is longer.

R//RL (input, active Low). This pin when connected to

GND disables the internal ROM and forces the device to

function as a Z86C96 ROMless Z8. (Note: When left

unconnected or pulled High to V

the part functions as a

normal Z86C61/62 ROM version.) This pin is only available

on the 44-pin version of the Z86C61, and both versions of

the Z86C62.

/DS (output, active Low). Data Strobe is activated once for

each external memory transfer. For a READ operation,

data must be available prior to the trailing edge of /DS. For

WRITE operations, the falling edge of /DS indicates that

output data is valid.

/AS (output, active Low). Address Strobe is pulsed once

at the beginning of each machine cycle. Address out-

put is through Port 1 for all external programs. Memory

address transfers are valid at the trailing edge of /AS.

Under program control, /AS can be placed in the high-

impedance state along with Ports 0 and 1, Data Strobe,

and Read/Write.

Pin # Symbol Function Direction

24-31 P07-P00 Port 0, Pins 0,1,2,3,4,5,6,7 In/Output

32 V

Power Supply Input

33-36 P55-P52 Port 5, Pins 2,3,4,5 In/Output

37-38 P11-P10 Port 1, Pins 0,1 In/Output

39-40 P57-P56 Port 5, Pins 6,7 In/Output

41-46 P17-P12 Port 1, Pins 2,3,4,5,6,7 In/Output

47-48 P63-P62 Port 6, Pins 3,2 In/Output

49 P34 Port 3, Pin 4 Output

50 P33 Port 3, Pin 3 Input

51 GND Ground Input

52 /SYNC Synchronization Output

53 SCLK System Clock Output

54-55 P21-P20 Port 2, Pins 0,1 In/Output

56-57 P61-P60 Port 6, Pins1,0 In/Output

58-63 P27-P22 Port 2, Pins 2,3,4,5,6,7 In/Output

64-65 P41-P40 Port 4, Pins 0,1 In/Output

66 P31 Port 3, Pin 1 Input

67 P36 Port 3, Pin 6 Output

68 P42 Port 4, Pin 2 In/Output

Z86C61/62/96

MICROCONTROLLER

and P35 are used as the handshake control /DAV0 and

RDY0 (Data Available and Ready). Handshake signal

assignment is dictated by the I/O direction of the upper

nibble P07-P04. The lower nibble must have the same

direction as the upper nibble to be under handshake

control.

For external memory references, Port 0 can provide ad-

dress bits A11-A8 (lower nibble) or A15-A8 (lower and

upper nibble) depending on the required address space.

If the address range requires 12 bits or less, the upper

nibble of Port 0 can be programmed independently as I/O

while the lower nibble is used for addressing. If one or both

nibbles are needed for I/O operation, they must be config-

ured by writing to the Port 0 Mode register.

In ROMless mode, after a hardware reset, Port 0 lines are

defined as address lines A15-A8, and extended timing is

set to accommodate slow memory access. The initializa-

tion routine includes reconfiguration to eliminate this ex-

tended timing mode (Figure 10).

/P0DS

Port 0 Data Strobe

(output, active Low). Signal used

to emulate Port 0 when in ROMless mode.

/P1DS

Port 1 Data Strobe

(output, active Low). Signal used

to emulate Port 1 when in ROMless mode.

/DTIMERS

Disable Timers

(input, active Low). All timers

are stopped by the Low level at this pin. This pin has an

internal pull up resistor.

SCLK (output). System clock pin.

/SYNC

Instruction SYNC Signal

(output, active Low). This

signal indicates the last clock of the current executing

instruction.

Port 0 (P07-P00). Port 0 is an 8-bit, nibble programmable,

bidirectional, TTL compatible port. These eight I/O lines

can be configured under software control as a nibble I/O

port, or as an address port for interfacing external memory.

When used as an I/O port, Port 0 may be placed under

handshake control. In this configuration, Port 3, lines P32

OEN

Out

PAD

Port 0 (I/O)

Handshake Controls

/DAV0 and RDY0

(P32 and P35)

MCU

TTL Level Shifter

Auto Latch

R ≈ 500 KΩ

Figure 10. Port 0 Configuration

Z86C61/62/96

MICROCONTROLLER

PIN FUNCTIONS (Continued)

Port 1 (P17-P10). Port 1 is an 8-bit, byte programmable,

bidirectional, TTL compatible port. It has multiplexed Ad-

dress (A7-A0) and Data (D7-D0) ports. For Z86C61/62/96,

these eight I/O lines can be programmed as Input or

Output lines or can be configured under software control

as an address/data port for interfacing external memory.

When used as an I/O port, Port 1 may be placed under

handshake control. In this configuration, Port 3 line P33

and P34 are used as the handshake controls RDY1 and

/DAV1.

Memory locations greater than 16,384 are referenced

through Port 1. To interface external memory, Port 1 must

be programmed for the multiplexed Address/Data mode.

If more than 256 external locations are required, Port 0

must output the additional lines.

Port 1 can be placed in high-impedance state along with

Port 0, /AS, /DS, and R//W, allowing the microcontroller to

share common resources in multiprocessor and DMA

applications. Data transfers can be controlled by assign-

ing P33 as a Bus Acknowledge input, and P34 as a Bus

request output (Figure 11).

OEN

Out

PAD

Port 1

(AD7-AD0)

MCU

TTL Level Shifter

Auto Latch

R ≈ 500 KΩ

Handshake Controls

/DAV1 and RDY1

(P33 and P34)

Figure 11. Port 1 Configuration

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