Intel Corporation MA80C186XL20, MA80C186XL16, MA80C186XL12, MA80C186XL10 Datasheet

*Other brands and names are the property of their respective owners.

Information in this document is provided in connection with Intel products. Intel assumes no liability whatsoever, including infringement of any patent or
copyright, for sale and use of Intel products except as provided in Intel’s Terms and Conditions of Sale for such products. Intel retains the right to make
changes to these specifications at any time, without notice. Microcomputer Products may have minor variations to this specification known as errata.

March 1995COPYRIGHT©INTEL CORPORATION, 1996 Order Number: 271276-002

M80C186XL20, 16, 12, 10

16-BIT HIGH-INTEGRATION EMBEDDED PROCESSOR

Y

Low Power, Full Static Version of
M80C186

Y

Operation Modes:
Ð Enhanced Mode

Ð DRAM Refresh Control Unit
Ð Power-Save Mode
Ð Direct Interface to 80C187

Ð Compatible Mode

Ð NMOS 80186 Pin-for-Pin

Replacement for Non-Numerics
Applications

Y

Integrated Feature Set
Ð Static, Modular CPU
Ð Clock Generator
Ð 2 Independent DMA Channels
Ð Programmable Interrupt Controller
Ð 3 Programmable 16-Bit Timers
Ð Dynamic RAM Refresh Control Unit
Ð Programmable Memory and

Peripheral Chip Select Logic
Ð Programmable Wait State Generator
Ð Local Bus Controller
Ð Power-Save Mode
Ð System-Level Testing Support (High

Impedance Test Mode)

Y

Completely Object Code Compatible
with Existing 8086/8088 Software and
Has 10 Additional Instructions over
8086/8088

Y

Speed Versions Available
Ð 20 MHz (M80C186XL20)
Ð 16 MHz (M80C186XL16)
Ð 12.5 MHz (M80C186XL12)
Ð 10 MHz (M80C186XL)

Y

Direct Addressing Capability to
1 MByte Memory and 64 Kbyte I/O

Y

Complete System Development
Support
Ð All 8086 and 80C186 Software

Development Tools Can Be Used for
M80C186XL System Development

Ð ASM 86 Assembler, PL/M-86,

Pascal-86, Fortran-86, iC-86 and
System Utilities

Ð In-Circuit-Emulator (ICE

TM

-186)

Y

Available in 68-Pin:
Ð Ceramic Pin Grid Array (PGA)

Y

Military Temperature Range:
Ð

b

55§Ctoa125§C(TC)

The Intel M80C186XL is a Modular Core re-implementation of the M80C186 microprocessor. It offers higher
speed and lower power consumption than the standard M80C186 but maintains 100% clock-for-clock func­tional compatibility. Packaging and pinout are also identical.

271276– 1

M80C186XL20, 16, 12, 10

16-BIT HIGH INTEGRATION EMBEDDED PROCESSOR

CONTENTS PAGE

INTRODUCTION ААААААААААААААААААААААААА 10

M80C186XL BASE ARCHITECTURE ААААА 10

M80C186XL Clock Generator ААААААААААААА 10
Bus Interface Unit ААААААААААААААААААААААААА 11

M80C186XL PERIPHERAL

ARCHITECTURE ААААААААААААААААААААААА 11

Chip-Select/Ready Generation Logic АААААА 11
DMA Unit ААААААААААААААААААААААААААААААААА 12
Timer/Counter Unit ААААААААААААААААААААААА 12
Interrupt Control Unit АААААААААААААААААААААА 12
Enhanced Mode Operation АААААААААААААААА 12
Queue-Status Mode ААААААААААААААААААААААА 12
DRAM Refresh Control Unit ААААААААААААААА 13
Power-Save Control ААААААААААААААААААААААА 13
Interface for 80C187 Math

Coprocessor АААААААААААААААААААААААААААА 13

ONCE Test Mode ААААААААААААААААААААААААА 13

ABSOLUTE MAXIMUM RATINGS АААААААА 14

DC CHARACTERISTICS ААААААААААААААААА 14

CONTENTS PAGE

AC CHARACTERISTICS ААААААААААААААААА 16

Major Cycle Timings (Read Cycle) ААААААААА 16
Major Cycle Timings (Write Cycle) ААААААААА 18
Major Cycle Timings (Interrupt

Acknowledge Cycle) АААААААААААААААААААА 20
Software Halt Cycle Timings ААААААААААААААА 22
Clock Timings ААААААААААААААААААААААААААААА 23
Ready, Peripheral and Queue Status

Timings

ААААААААААААААААААААААААААААААААА 25

Reset and Hold/HLDA Timings АААААААААААА 27

AC TIMING WAVEFORMS ААААААААААААААА 33

EXPLANATION OF THE AC

SYMBOLS АААААААААААААААААААААААААААААА 36

DERATING CURVES ААААААААААААААААААААА 37

M80C186XL EXECUTION TIMINGS АААААА 38

INSTRUCTION SET SUMMARY АААААААААА 39

FOOTNOTES ААААААААААААААААААААААААААААА 44

2

M80C186XL

Figure 1. M80C186XL Block Diagram

271276– 2

3

M80C186XL

Ceramic Pin Grid Array

Pins Facing Up Pins Facing Down

271276– 3

NOTE:

XXXXXXXXA indicates the Intel FPO number.

Figure 2. M80C186XL Pinout Diagrams

4

M80C186XL

Table 1. M80C186XL Pin Description

Symbol

PGA

Type Name and Function

Pin No.

V

CC

9 I System Power:a5 volt power supply.

43 I

V

SS

26 I System Ground.
60 I

RESET 57 O RESET Output indicates that the M80C186XL CPU is being reset, and

can be used as a system reset. It is active HIGH, synchronized with
the processor clock, and lasts an integer number of clock periods
corresponding to the length of the RES

signal. Reset goes inactive 2

clockout periods after RES

goes inactive. When tied to the TEST/
BUSY pin, RESET forces the M80C186XL into enhanced mode.
RESET is not floated during bus hold.

X1 59 I Crystal Inputs X1 and X2 provide external connections for a

fundamental mode or third overtone parallel resonant crystal for the

X2 58 O

internal oscillator. X1 can connect to an external clock instead of a
crystal. In this case, minimize the capacitance on X2. The input or
oscillator frequency is internally divided by two to generate the clock
signal (CLKOUT).

CLKOUT 56 O Clock Output provides the system with a 50% duty cycle waveform.

All device pin timings are specified relative to CLKOUT. CLKOUT is
active during reset and bus hold.

RES 24 I An active RES causes the M80C186XL to immediately terminate its

present activity, clear the internal logic, and enter a dormant state.
This signal may be asynchronous to the M80C186XL clock. The
M80C186XL begins fetching instructions approximately 6(/2 clock
cycles after RES

is returned HIGH. For proper initialization, VCCmust
be within specifications and the clock signal must be stable for more
than 4 clocks with RES

held LOW. RES is internally synchronized.
This input is provided with a Schmitt-trigger to facilitate power-on RES
generation via an RC network.

TEST/BUSY 47 I/O The TEST pin is sampled during and after reset to determine whether

the M80C186XL is to enter Compatible or Enhanced Mode. Enhanced
Mode requires TEST

to be HIGH on the rising edge of RES and LOW
four CLKOUT cycles later. Any other combination will place the
M80C186XL in Compatible Mode. During power-up, active RES is
required to configure TEST

/BUSY as an input. A weak internal pullup

ensures a HIGH state when the input is not externally driven.

TEST

ÐIn Compatible Mode this pin is configured to operate as TEST.

This pin is examined by the WAIT instruction. If the TEST

input is
HIGH when WAIT execution begins, instruction execution will
suspend. TEST

will be resampled every five clocks until it goes LOW,
at which time execution will resume. If interrupts are enabled while the
M80C186XL is waiting for TEST

, interrupts will be serviced.

BUSYÐIn Enhanced Mode, this pin is configured to operate as
BUSY. The BUSY input is used to notify the M80C186XL of Math
Coprocessor activity. Floating point instructions executing in the
M80C186XL sample the BUSY pin to determine when the Math
Coprocessor is ready to accept a new command. BUSY is active
HIGH.

5

M80C186XL

Table 1. M80C186XL Pin Description (Continued)

Symbol

PGA

Type Name and Function

Pin No.

TMR IN 0 20 I Timer Inputs are used either as clock or control signals,

depending upon the programmed timer mode. These inputs are

TMR IN 1 21 I

active HIGH (or LOW-to-HIGH transitions are counted) and
internally synchronized. Timer Inputs must be tied HIGH when
not being used as clock or retrigger inputs.

TMR OUT 0 22 O Timer outputs are used to provide single pulse or continous

waveform generation, depending upon the timer mode selected.

TMR OUT 1 23 O

These outputs are not floated during a bus hold.

DRQ0 18 I DMA Request is asserted HIGH by an external device when it is

ready for DMA Channel 0 or 1 to perform a transfer. These

DRQ1 19 I

signals are level-triggered and internally synchronized.

NMI 46 I The Non-Maskable Interrupt input causes a Type 2 interrupt. An

NMI transition from LOW to HIGH is latched and synchronized
internally, and initiates the interrupt at the next instruction
boundary. NMI must be asserted for at least one CLKOUT period.
The Non-Maskable Interrupt cannot be avoided by programming.

INT0 45 I Maskable Interrupt Requests can be requested by activating one

of these pins. When configured as inputs, these pins are active

INT1/SELECT

44 I

HIGH. Interrupt Requests are synchronized internally. INT2 and

INT2/INTA0

42 I/O

INT3 may be configured to provide active-LOW interrupt-

INT3/INTA1

/IRQ 41 I/O

acknowledge output signals. All interrupt inputs may be
configured to be either edge- or level-triggered. To ensure
recognition, all interrupt requests must remain active until the
interrupt is acknowledged. When Slave Mode is selected, the
function of these pins changes (see Interrupt Controller section
of this data sheet).

A19/S6 65 O Address Bus Outputs (16 –19) and Bus Cycle Status (3 –6)

indicate the four most significant address bits during T

1

. These

A18/S5 66 O

signals are active HIGH.

A17/S4 67 O
A16/S3 68 O During T

2,T3,TW

and T4, the S6 pin is LOW to indicate a CPU­initiated bus cycle or HIGH to indicate a DMA-initiated or refresh
bus cycle. During the same T-states, S3, S4 and S5 are always
LOW. These outputs are floated during bus hold or reset.

AD15 1 I/O Address/Data Bus (0 –15) signals constitute the time multiplexed

memory or I/O address (T

1

) and data (T2,T3,TWand T4) bus.

AD14 3 I/O

The bus is active HIGH. A

0

is analogous to BHE for the lower

AD13 5 I/O

byte of the data bus, pins D

7

through D0. It is LOW during T

1

AD12 7 I/O

when a byte is to be transferred onto the lower portion of the bus

AD11 10 I/O

in memory or I/O operations. These pins are floated during a bus

AD10 12 I/O

hold or reset.

AD9 14 I/O
AD8 16 I/O
AD7 2 I/O
AD6 4 I/O
AD5 6 I/O
AD4 8 I/O
AD3 11 I/O
AD2 13 I/O
AD1 15 I/O
AD0 17 I/O

6

M80C186XL

Table 1. M80C186XL Pin Description (Continued)

Symbol

PGA

Type Name and Function

Pin No.

BHE 64 O The BHE (Bus High Enable) signal is analogous to A0 in that it is used

to enable data on to the most significant half of the data bus, pins D15–
D8. BHE

will be LOW during T1when the upper byte is transferred and

will remain LOW through T

3

AND TW. BHE does not need to be latched.

BHE

will float during HOLD or RESET.

In Enhanced Mode, BHE will also be used to signify DRAM refresh
cycles. A refresh cycle is indicated by both BHE

and A0 being HIGH.

BHE and A0 Encodings

BHE A0

Function

Value Value

0 0 Word Transfer
0 1 Byte Transfer on upper half of data bus (D15–D8)
1 0 Byte Transfer on lower half of data bus (D

7–D0

)

1 1 Refresh

ALE/QS0 61 O Address Latch Enable/Queue Status 0 is provided by the M80C186XL

to latch the address. ALE is active HIGH, with addresses guaranteed
valid on the trailing edge.

WR/QS1 63 O Write Strobe/Queue Status 1 indicates that the data on the bus is to be

written into a memory or an I/O device. It is active LOW, and floats
during bus hold or reset. When the M80C186XL is in Queue Status
Mode, the ALE/QS0 and WR

/QS1 pins provide information about

processor/instruction queue interaction.

QS1 QS0 Queue Operation

0 0 No queue operation
0 1 First opcode byte fetched from the queue
1 1 Subsequent byte fetched from the queue
1 0 Empty the queue

RD/QSMD 62 O/I Read Strobe is an active LOW signal which indicates that the

M80C186XL is performing a memory or I/O read cycle. It is guaranteed
not to go LOW before the A/D bus is floated. An internal pull-up
ensures that RD

/QSMD is HIGH during RESET. Following RESET the
pin is sampled to determine whether the M80C186XL is to provide ALE,
RD

, and WR, or queue status information. To enable Queue Status

Mode, RD

must be connected to GND. RD will float during bus HOLD.

ARDY 55 I Asynchronous Ready informs the M80C186XL that the addressed

memory space or I/O device will complete a data transfer. The ARDY
pin accepts a rising edge that is asynchronous to CLKOUT and is active
HIGH. The falling edge of ARDY must be synchronized to the
M80C186XL clock. Connecting ARDY HIGH will always assert the
ready condition to the CPU. If this line is unused, it should be tied LOW
to yield control to the SRDY pin.

SRDY 49 I Synchronous Ready informs the M80C186XL that the addressed

memory space or I/O device will complete a data transfer. The SRDY
pin accepts an active-HIGH input synchronized to CLKOUT. The use of
SRDY allows a relaxed system timing over ARDY. This is accomplished
by elimination of the one-half clock cycle required to internally
synchonize the ARDY input signal. Connecting SRDY high will always
assert the ready condition to the CPU. If this line is unused, it should be
tied LOW to yield control to the ARDY pin.

7

M80C186XL

Table 1. M80C186XL Pin Description (Continued)

Symbol

PGA

Type Name and Function

Pin No.

LOCK 48 O LOCK output indicates that other system bus masters are not to gain

control of the system bus. LOCK

is active LOW. The LOCK signal is
requested by the LOCK prefix instruction and is activated at the beginning
of the first data cycle associated with the instruction immediately following
the LOCK prefix. It remains active until the completion of that instruction.
No instruction prefetching will occur while LOCK is asserted. LOCK floats
during bus hold or reset.

S0 52 O Bus cycle status S0 –S2

are encoded to provide bus-transaction

information:

S1

53 O

S2 54 O

M80C186XL Bus Cycle Status Information

S2 S1 S0 Bus Cycle Initiated

0 0 0 Interrupt Acknowledge
0 0 1 Read I/O
0 1 0 Write I/O
0 1 1 Halt
1 0 0 Instruction Fetch
1 0 1 Read Data from Memory
1 1 0 Write Data to Memory
1 1 1 Passive (no bus cycle)

The status pins float during HOLD.
S2

may be used as a logical M/IO indicator, and S1 as a DT/R indicator.

HOLD 50 I HOLD indicates that another bus master is requesting the local bus. The

HOLD input is active HIGH. The M80C186XL generates HLDA (HIGH) in

HLDA 51 O

response to a HOLD request. Simultaneous with the issuance of HLDA,
the M80C186XL will float the local bus and control lines. After HOLD is
detected as being LOW, the M80C186XL will lower HLDA. When the
M80C186XL needs to run another bus cycle, it will again drive the local bus
and control lines.

In Enhanced Mode, HLDA will go low when a DRAM refresh cycle is
pending in the M80C186XL and an external bus master has control of the
bus. It will be up to the external master to relinquish the bus by lowering
HOLD so that the M80C186XL may execute the refresh cycle.

UCS 34 O/I Upper Memory Chip Select is an active LOW output whenever a memory

reference is made to the defined upper portion (1K – 256K block) of
memory. UCS

does not float during bus hold. The address range activating

UCS

is software programmable.

UCS and LCS are sampled upon the rising edge of RES. If both pins are
held low, the M80C186XL will enter ONCE Mode. In ONCE Mode all pins
assume a high impedance state and remain so until a subsequent RESET.
UCS has a weak internal pullup that is active during RESET to ensure that
the M80C186XL does not enter ONCE Mode inadvertently.

LCS 33 O/I Lower Memory Chip Select is active LOW whenever a memory reference is

made to the defined lower portion (1K –256K) of memory. LCS

does not

float during bus HOLD. The address range activating LCS

is software

programmable.

8

M80C186XL

Table 1. M80C186XL Pin Description (Continued)

Symbol

PGA

Type Name and Function

Pin No.

LCS UCS and LCS are sampled upon the rising edge of RES. If both

pins are held low, the M80C186XL will enter ONCE Mode. In ONCE

(Continued)

Mode all pins assume a high impedance state and remain so until a
subsequent RESET. LCS

has a weak internal pullup that is active

only during RESET to ensure that the M80C186XL does not enter
ONCE mode inadvertently.

MCS0/PEREQ 38 O/I Mid-Range Memory Chip Select signals are active LOW when a

memory reference is made to the defined mid-range portion of

MCS1

/ERROR 37 O/I

memory (8K –512K). These lines do not float during bus HOLD. The

MCS2

36 O

address ranges activating MCS0 – 3

are software programmable.

MCS3

/NPS 35 O

In Enhanced Mode, MCS0

becomes a PEREQ input (Processor
Extension Request). When connected to the Math Coprocessor,
this input is used to signal the M80C186XL when to make numeric
data transfers to and from the coprocessor. MCS3

becomes NPS
(Numeric Processor Select) which may only be activated by
communication to the 80C187. MCS1

becomes ERROR in

Enhanced Mode and is used to signal numerics coprocessor errors.

MCS0

/PEREQ and MCS1/ERROR have weak internal pullups

which are active during reset.

PCS0 25 O Peripheral Chip Select signals 0–4 are active LOW when a

reference is made to the defined peripheral area (64K byte I/O or 1

PCS1

27 O

MByte memory space). These lines do not float during bus HOLD.

PCS2

28 O

The address ranges activating PCS0–4

are software

PCS3

29 O

programmable.

PCS4

30 O

PCS5/A1 31 O Peripheral Chip Select 5 or Latched A1 may be programmed to

provide a sixth peripheral chip select, or to provide an internally
latched A1 signal. The address range activating PCS5 is software­programmable. PCS5

/A1 does not float during bus HOLD. When
programmed to provide latched A1, this pin will retain the previously
latched value during HOLD.

PCS6/A2 32 O Peripheral Chip Select 6 or Latched A2 may be programmed to

provide a seventh peripheral chip select, or to provide an internally
latched A2 signal. The address range activating PCS6

is software­programmable. PCS6/A2 does not float during bus HOLD. When
programmed to provide latched A2, this pin will retain the previously
latched value during HOLD.

DT/R 40 O Data Transmit/Receive controls the direction of data flow through

an external data bus transceiver. When LOW, data is transferred to
the M80C186XL. When HIGH the M80C186XL places write data on
the data bus. DT/R

floats during a bus hold or reset.

DEN 39 O Data Enable is provided as a data bus transceiver output enable.

DEN

is active LOW during each memory and I/O access (including

80C187 access). DEN

is HIGH whenever DT/R changes state.

During RESET, DEN

is driven HIGH for one clock, then floated.

DEN

also floats during HOLD.

N.C. Ð Ð Not connected. To maintain compatibility with future products, do

not connect to these pins.

9

M80C186XL

271276– 4

(3a)

271276– 5

(3b)

Note 1:

XTAL Frequency L1 Value

20 MHz 12.0 mH

g

20%

25 MHz 8.2 mH

g

20%

32 MHz 4.7 mH

g

20%

40 MHz 3.0 mH

g

20%
LC network is only required when using a third
overtone crystal.

Figure 3. M80C186XL Oscillator Configurations (see text)

INTRODUCTION

The following Functional Description describes the
base architecture of the M80C186XL. The
M80C186XL is a very high integration 16-bit micro­processor. It combines 15 –20 of the most common
microprocessor system components onto one chip.
The M80C186XL is object code compatible with the
8086/8088 microprocessors and adds 10 new in­struction types to the 8086/8088 instruction set.

The M80C186XL has two major modes of operation,
Compatible and Enhanced. In Compatible Mode the
M80C186XL is completely compatible with NMOS
80186, with the exception of 8087 support. The En­hanced mode adds three new features to the system
design. These are Power-Save control, Dynamic
RAM refresh, and an asynchronous Numerics Co­processor interface.

M80C186XL BASE ARCHITECTURE

M80C186XL Clock Generator

The M80C186XL provides an on-chip clock genera­tor for both internal and external clock generation.
The clock generator features a crystal oscillator, a
divide-by-two counter, synchronous and asynchro­nous ready inputs, and reset circuitry.

The M80C186XL oscillator circuit is designed to be
used either with a parallel resonant fundamental or

third-overtone mode crystal, depending upon the
frequency range of the application. This is used as
the time base for the M80C186XL.

The output of the oscillator is not directly available
outside the M80C186XL. The recommended crystal
configuration is shown in Figure 3b. When used in
third-overtone mode, the tank circuit is recommend­ed for stable operation. Alternately, the oscillator
may be driven from an external source as shown in
Figure 3a.

The crystal or clock frequency chosen must be twice
the required processor operating frequency due to
the internal divide by two counter. This counter is
used to drive all internal phase clocks and the exter­nal CLKOUT signal. CLKOUT is a 50% duty cycle
processor clock and can be used to drive other sys­tem components. All AC Timings are referenced to
CLKOUT.

Intel recommends the following values for crystal se­lection parameters.

Temperature Range: Application Specific

ESR (Equivalent Series Resistance): 60X max

C

0

(Shunt Capacitance of Crystal): 7.0 pF max

C1(Load Capacitance): 20 pFg5pF

Drive Level: 2 mW max

10

M80C186XL

Bus Interface Unit

The M80C186XL provides a local bus controller to
generate the local bus control signals. In addition, it
employs a HOLD/HLDA protocol for relinquishing
the local bus to other bus masters. It also provides
outputs that can be used to enable external buffers
and to direct the flow of data on and off the local
bus.

The bus controller is responsible for generating 20
bits of address, read and write strobes, bus cycle
status information and data (for write operations) in­formation. It is also responsible for reading data
from the local bus during a read operation. Synchro­nous and asynchronous ready input pins are provid­ed to extend a bus cycle beyond the minimum four
states (clocks).

The M80C186XL bus controller also generates two
control signals (DEN

and DT/R) when interfacing to
external transceiver chips. This capability allows the
addition of transceivers for simple buffering of the
multiplexed address/data bus.

During RESET the local bus controller will perform
the following action:

#

Drive DEN

,RDand WR HIGH for one clock cy-

cle, then float them.

#

Drive S0–S2 to the inactive state (all HIGH) and
then float.

#

Drive LOCK HIGH and then float.

#

Float AD0–15, A16 – 19, BHE, DT/R.

#

Drive ALE LOW

#

Drive HLDA LOW.

RD

/QSMD, UCS, LCS, MCS0/PEREQ, MCS1/

ERROR

and TEST/BUSY pins have internal pullup

devices which are active while RES

is applied. Ex­cessive loading or grounding certain of these pins
causes the M80C186XL to enter an alternative
mode of operation:

#

RD/QSMD low results in Queue Status Mode.

#

UCS and LCS low results in ONCE Mode.

#

TEST/BUSY low (and high later) results in En­hanced Mode.

M80C186XL PERIPHERAL
ARCHITECTURE

All the M80C186XL integrated peripherals are con­trolled by 16-bit registers contained within an inter­nal 256-byte control block. The control block may be
mapped into either memory or I/O space. Internal
logic will recognize control block addresses and re­spond to bus cycles. An offset map of the 256-byte
control register block is shown in Figure 4.

Chip-Select/Ready Generation Logic

The M80C186XL contains logic which provides pro­grammable chip-select generation for both memo­ries and peripherals. In addition, it can be pro­grammed to provide READY (or WAIT state) genera­tion. It can also provide latched address bits A1 and
A2. The chip-select lines are active for all memory
and I/O cycles in their programmed areas, whether
they be generated by the CPU or by the integrated
DMA unit.

The M80C186XL provides 6 memory chip select out­puts for 3 address areas; upper memory, lower
memory, and midrange memory. One each is provid­ed for upper memory and lower memory, while four
are provided for midrange memory.

OFFSET

Relocation Register FEH

DMA Descriptors Channel 1

DAH

D0H

DMA Descriptors Channel 0

CAH

C0H

Chip-Select Control Registers

A8H

A0H

Time 2 Control Registers

66H

60H

Time 1 Control Registers

5EH

58H

Time 0 Control Registers

56H

50H

Interrupt Controller Registers

3EH

20H

Figure 4. Internal Register Map

The M80C186XL provides a chip select, called UCS

,
for the top of memory. The top of memory is usually
used as the system memory because after reset the
M80C186XL begins executing at memory location
FFFF0H.

11

M80C186XL

The M80C186XL provides a chip select for low
memory called LCS

. The bottom of memory con­tains the interrupt vector table, starting at location
00000H.

The M80C186XL provides four MCS lines which are
active within a user-locatable memory block. This
block can be located within the M80C186XL 1 Mbyte
memory address space exclusive of the areas de­fined by UCS

and LCS. Both the base address and

size of this memory block are programmable.

The M80C186XL can generate chip selects for up to
seven peripheral devices. These chip selects are ac­tive for seven contiguous blocks of 128 bytes above
a programmable base address. The base address
may be located in either memory or I/O space.

The M80C186XL can generate a READY signal in­ternally for each of the memory or peripheral CS
lines. The number of WAIT states to be inserted for
each peripheral or memory is programmable to pro­vide 0–3 wait states for all accesses to the area for
which the chip select is active. In addition, the
M80C186XL may be programmed to either ignore
external READY for each chip-select range individu­ally or to factor external READY with the integrated
ready generator.

Upon RESET, the Chip-Select/Ready Logic will per­form the following actions:

#

All chip-select outputs will be driven HIGH.

#

Upon leaving RESET, the UCS line will be pro­grammed to provide chip selects to a 1K block
with the accompanying READY control bits set at
011 to insert 3 wait states in conjunction with ex­ternal READY (i.e., UMCS resets to FFFBH).

#

No other chip select or READY control registers
have any predefined values after RESET. They
will not become active until the CPU accesses
their control registers.

DMA Unit

The M80C186XL DMA controller provides two inde­pendent high-speed DMA channels. Data transfers
can occur between memory and I/O spaces (e.g.,
Memory to I/O) or within the same space (e.g.,
Memory to Memory or I/O to I/O). Data can be
transferred either in bytes (8 bits) or in words (16
bits) to or from even or odd addresses. Each DMA
channel maintains both a 20-bit source and destina­tion pointer which can be optionally incremented or
decremented after each data transfer (by one or two
depending on byte or word transfers). Each data
transfer consumes 2 bus cycles (a minimum of 8
clocks), one cycle to fetch data and the other to
store data.

Timer/Counter Unit

The M80C186XL provides three internal 16-bit pro­grammable timers. Two of these are highly flexible
and are connected to four external pins (2 per timer).
They can be used to count external events, time ex­ternal events, generate nonrepetitive waveforms,
etc. The third timer is not connected to any external
pins, and is useful for real-time coding and time de­lay applications. In addition, the third timer can be
used as a prescaler to the other two, or as a DMA
request source.

Interrupt Control Unit

The M80C186XL can receive interrupts from a num­ber of sources, both internal and external. The
M80C186XL has 5 external and 2 internal interrupt
sources (Timer/Couners and DMA). The internal in­terrupt controller serves to merge these requests on
a priority basis, for individual service by the CPU.

Enhanced Mode Operation

In Compatible Mode the M80C186XL operates with
all the features of the NMOS 80186, with the excep­tion of 8087 support (i.e. no math coprocessing is
possible in Compatible Mode). Queue-Status infor­mation is still available for design purposes other
than 8087 support.

All the Enhanced Mode features are completely
masked when in Compatible Mode. A write to any of
the Enhanced Mode registers will have no effect,
while a read will not return any valid data.

In Enhanced Mode, the M80C186XL will operate
with Power-Save, DRAM refresh, and numerics co­processor support in addition to all the Compatible
Mode features.

If connected to a math coprocessor, this mode will
be invoked automatically. Without an NPX, this
mode can be entered by tying the RESET output
signal from the M80C186XL to the TEST

/BUSY in-

put.

Queue-Status Mode

The queue-status mode is entered by strapping the
RD

pin low. RD is sampled at RESET and if LOW,
the M80C186XL will reconfigure the ALE and WR
pins to be QS0 and QS1 respectively. This mode is
available on the M80C186XL in both Compatible
and Enhanced Modes.

12

M80C186XL

DRAM Refresh Control Unit

The Refresh Control Unit (RCU) automatically gen­erates DRAM refresh bus cycles. The RCU operates
only in Enhanced Mode. After a programmable peri­od of time, the RCU generates a memory read re­quest to the BIU. If the address generated during a
refresh bus cycle is within the range of a properly
programmed chip select, that chip select will be acti­vated when the BIU executes the refresh bus cycle.

Power-Save Control

The M80C186XL, when in Enhanced Mode, can en­ter a power saving state by internally dividing the
processor clock frequency by a programmable fac­tor. This divided frequency is also available at the
CLKOUT pin.

All internal logic, including the Refresh Control Unit
and the timers, have their clocks slowed down by
the division factor. To maintain a real time count or a
fixed DRAM refresh rate, these peripherals must be
re-programmed when entering and leaving the pow­er-save mode.

Interface for 80C187 Math
Coprocessor

In Enhanced Mode, three of the mid-range memory
chip selects are redefined according to Table 2 for
use with the 80C187. The fourth chip select, MCS2
functions as in compatible mode, and may be pro-

grammed for activity with ready logic and wait states
accordingly. As in Compatible Mode, MCS2

will func-

tion for one-fourth a programmed block size.

Table 2. MCS

Assignments

Compatible

Enhanced Mode

Mode

MCS0 PEREQ Processor Extension Request
MCS1

ERROR NPX Error

MCS2

MCS2 Mid-Range Chip Select

MCS3

NPS Numeric Processor Select

ONCE Test Mode

To facilitate testing and inspection of devices when
fixed into a target system, the M80C186XL has a
test mode available which allows all pins to be
placed in a high-impedance state. ONCE stands for
‘‘ON Circuit Emulation’’. When placed in this mode,
the M80C186XL will put all pins in the high-imped­ance state until RESET.

The ONCE mode is selected by tying the UCS

and

the LCS

LOW during RESET. These pins are sam-

pled on the low-to-high transition of the RES

pin.

The UCS

and the LCS pins have weak internal pull-

up resistors similar to the RD

and TEST/BUSY pins
to guarantee ONCE Mode is not entered inadver­tently during normal operation. LCS

and UCS must

be held low at least one clock after RES

goes high

to guarantee entrance into ONCE Mode.

13

M80C186XL

ABSOLUTE MAXIMUM RATINGS*

Case Temperature under Bias ÀÀÀb55§Ctoa125§C

Storage Temperature ААААААААААb65§Ctoa150§C

Voltage on Any Pin with

Respect to Ground АААААААААААА

b

1.0V toa7.0V

/Package Power Dissipation АААААААААААААААААА1W
Not to exceed the maximum allowable die tempera­ture based on thermal resistance of the package.

NOTICE: This data sheet contains information on
products in the sampling and initial production phases
of development. It is valid for the devices indicated in
the revision history. The specifications are subject to
change without notice.

*

WARNING: Stressing the device beyond the ‘‘Absolute
Maximum Ratings’’ may cause permanent damage.
These are stress ratings only. Operation beyond the
‘‘Operating Conditions’’ is not recommended and ex­tended exposure beyond the ‘‘Operating Conditions’’
may affect device reliability.

NOTICE: The specifications are subject to change
without notice.

DC CHARACTERISTICS T

C

eb

55§Ctoa125§C, V

CC

e

5Vg10%

Symbol Parameter Min Max Units Test Conditions

V

IL

Input Low Voltage (Except X1)

b

0.5 0.2 V

CC

b

0.3 V

V

IL1

Clock Input Low Voltage (X1)

b

0.5 0.6 V

V

IH

Input High Voltage 0.2 V

CC

a

0.9 V

CC

a

0.5 V

(All except X1 and RES

)

V

IH1

Input High Voltage (RES) 3.0 V

CC

a

0.5 V

V

IH2

Clock Input High Voltage (X1) 3.9 V

CC

a

0.5 V

V

OL

Output Low Voltage 0.45 V I

OL

e

2.5 mA (S0, 1, 2)

I

OL

e

2.0 mA (others)

V

OH

Output High Voltage 2.4 V

CC

VI

OH

eb

2.4 mA@2.4V

(4)

V

CC

b

0.5 V

CC

VI

OH

eb

200 mA@V

CC

b

0.5

(4)

I

CC

Power Supply Current 100 mA@20 MHz,b55§C

V

CC

e

5.5V

(3)

90 mA@16 MHz,b55§C

V

CC

e

5.5V

(3)

80 mA@12.5 MHz,b55§C

V

CC

e

5.5V

(3)

70 mA@10 MHz,b55§C

V

CC

e

5.5V

(3)

I

LI

Input Leakage Current

g

10 mA@0.5 MHz,

0.45V

s

V

IN

s

V

CC

I

LO

Output Leakage Current

g

10 mA@0.5 MHz,

0.45VsV

OUT

s

V

CC

(1)

V

CLO

Clock Output Low 0.45 V I

CLO

e

4.0 mA

14