Preliminary Information
X86C64
Z8
®
Microcontroller Family Compatible
64K
X86C64
E
2
Micro-Peripheral
DESCRIPTION
8192 x 8 Bit
FEATURES
•
•
•
•
•
•
•
•
CONCURRENT READ WRITE
™
—Dual Plane Architecture
Isolates Read/Write Functions
Between Planes
Allows Continuous Execution of Code
From One Plane While Writing in the Other
Plane
Multiplexed Address/Data Bus
—Direct Interface to Popular 8-bit
Microcontrollers, e.g. Zilog Z8 Family
High Performance CMOS
—Fast Access Time, 120 ns
—Low Power
60 mA Maximum Active
200
µ
A Maximum Standby
Software Data Protection
Block Protect Register
—Individually Set Write Lock Out in 1K Blocks
Toggle Bit
—Early End of Write Detection
Page Mode Write
—Allows up to 32 Bytes to be Written in
One Write Cycle
High Reliability
—Endurance: 10,000 Write Cycle
—Data Retention: 100 Years
The X86C64 is an 8K x 8 E
2
PROM fabricated with
advanced CMOS Textured Poly Floating Gate Technol-
ogy. The X86C64 features a Multiplexed Address and
Data bus allowing direct interface to a variety of popular
single-chip microcontrollers operating in expanded mul-
tiplexed mode without the need for additional interface
circuitry.
The X86C64 is internally configured as two indepen-
dent 4K x 8 memory arrays. This feature provides the
ability to perform nonvolatile memory updates in one
array and continue operation out of code stored in the
other array; effectively eliminating the need for an aux-
iliary memory device for code storage.
To write to the X86C64, a three byte command
sequence must precede the byte(s) being written. The
X86C64 also provides a second generation software
data protection scheme called Block Protect. Block
Protect can provide write lockout of the entire device or
selected 1K blocks. There are eight, 1K x 8 blocks that
can be write protected individually in any combination
required by the user. Block Protect, in addition to Write
Control input, allows the different segments of the
memory to have varying degrees of alterability in nor-
mal system operation.
FUNCTIONAL DIAGRAM
CE
R/W
DS
SEL
A8–A11
CONTROL
LOGIC
X
D
E
C
O
D
E
WC
A12
SOFTWARE
DATA
PROTECT
A12
1K BYTES
1K BYTES
1K BYTES
1K BYTES
A12
M
U
X
1K BYTES
1K BYTES
1K BYTES
1K BYTES
AS
L
A
T
C
H
E
S
Y DECODE
I/O & ADDRESS LATCHES AND BUFFERS
A/D0–A/D7
Z8
®
is a registered trademark of Zilog Corporation
CONCURRENT READ WRITE
™
is a trademark of Xicor, Inc.
© Xicor, 1991 Patents Pending
3819-2.1 7/29/96 T0/C1/D1 SH
3819 FHD F02
1
Characteristics subject to change without notice
X86C64
PIN DESCRIPTIONS
Address/Data (A/D
0
–A/D
7
)
Multiplexed low-order addresses and data. The ad-
dresses flow into the device while
AS
is LOW. After
AS
transitions from a LOW to HIGH the addresses are
latched. Once the addresses are latched these pins input
data or output data depending on
DS,
R/W, and CE.
Addresses (A
8
–A
12
)
High order addresses flow into the device when
AS
= V
IL
and are latched when
AS
goes HIGH.
Chip Enable (CE)
The Chip Enable input must be HIGH to enable all read/
write operations. When CE is LOW and
AS
is HIGH, the
X86C64 is placed in the low power standby mode.
Data Strobe (DS)
When used with a Z8 the
DS
input is tied directly to the
DS
output of the microcontroller.
Read/Write (R/W)
When used with a Z8 the R/W input is tied directly to the
R/W output of the microcontroller.
Address Strobe (AS)
Addresses flow through the latches to address decoders
when
AS
is LOW and are latched when
AS
transitions
from a LOW to HIGH.
Device Select (SEL)
Must be connected to V
SS
.
Write Control (WC)
The Write Control allows external circuitry to abort a
page load cycle once it has been initiated. This input is
useful in applications in which a power failure or proces-
sor RESET could interrupt a page load cycle. In this
case, the microcontroller might drive all signals HIGH,
causing bad data to be latched into the E
2
PROM. If the
Write Control input is driven HIGH (before t
TBLC
Max)
after Read/Write (R/W) goes HIGH, the write cycle will
be aborted.
When
WC
is LOW (tied to V
SS
) the X86C64 will be
enabled to perform write operations. When
WC
is HIGH
normal read operations may be performed, but all at-
tempts to write to the device will be disabled.
PIN NAMES
Symbol
AS
A/D
0
–A/D
7
A
8
–A
12
DS
R/W
CE
WC
SEL
V
SS
V
CC
Description
Address Strobe
Address Inputs/Data I/O
Address Inputs
Data Strobe Input
Read/Write Input
Chip Enable
Write Control
Device Select—Connect to V
SS
Ground
Supply Voltage
3819 PGM T01
PIN CONFIGURATION
DIP/SOIC
NC
A12
NC
NC
WC
SEL
A/D0
A/D1
A/D2
A/D3
A/D4
VSS
1
2
3
4
5
6
7
8
9
10
11
12
X86C64
24
23
22
21
20
19
18
17
16
15
14
13
VCC
R/W
AS
A8
A9
A11
DS
A10
CE
A/D7
A/D6
A/D5
3819 FHD F01
2
X86C64
PRINCIPLES OF OPERATION
The X86C64 is a highly integrated peripheral device for
a wide variety of single-chip microcontrollers. The
X86C64 provides 8K bytes of 5-volt E
2
PROM which can
be used either for Program Storage, Data Storage or a
combination of both in systems based upon Von
Neumann (86XX) architectures. The X86C64 incorpo-
rates the interface circuitry normally needed to decode
the control signals and demultiplex the Address/Data
bus to provide a “ Seamless” interface.
The interface inputs on the X86C64 are configured such
that it is possible to directly connect them to the proper
interface signals of the appropriate single-chip
microcontroller.
The X86C64 is internally organized as two independent
planes of 4K bytes of memory with the A
12
input select-
ing which of the two planes of memory are to be
accessed. While the processor is executing code out of
one plane, write operations can take place in the other
plane, allowing the processor to continue execution of
code out of the X86C64 during a byte or page write to the
device.
The X86C64 also features an advanced implementation
of the Software Data Protection scheme, called Block
Protect, which allows the device to be broken into 8
independent sections of 1K bytes. Each of these sec-
tions can be independently enabled for write operations;
thereby allowing certain sections of the device to be
secured so that updates can only occur in a controlled
environment (e.g. in an automotive application, only at
an authorized service center). The desired set-up con-
figuration is stored in a nonvolatile register, ensuring the
configuration data will be maintained after the device is
powered down.
The X86C64 also features a Write Control input (WC),
which serves as an external control over the completion
of a previously initiated page load cycle.
The X86C64 also features the industry standard 5-volt
E
2
PROM characteristics such a byte or page mode write
and toggle-bit polling.
DEVICE OPERATION
Zilog Z8 operation requires the microcontroller’s
AS, DS
and R/W outputs tied to the X86C64
AS, DS
and
R/W inputs respectively.
The rising edge of
AS
will latch the addresses for both a
read and write operation. The state of R/W output
determines the operation to be performed, with the
DS
signal acting as a data strobe.
If R/W is HIGH and CE HIGH (read operation) data will
be output on A/D
0
–A/D
7
after
DS
transitions LOW. If
R/W is LOW and CE is HIGH (write operation) data
presented at A/D
0
–A/D
7
will be strobed into the X86C64
on the LOW to HIGH transition of
DS.
Typical Application
P10
P11
P12
P13
P14
P15
P16
P17
P00
P01
P02
P03
P04
P07
AS
DS
R/W
21
22
23
24
25
26
27
28
13
14
15
16
17
20
9
8
7
7
8
9
10
11
13
14
15
21
20
17
19
2
16
5
22
18
23
6
2
XTAL
3
EXTAL
A/D0
A/D1
A/D2
A/D3
A/D4
A/D5
A/D6
A/D7
A8
A9
A10
A11
A12
CE
WC
AS
DS
R/W
SEL
24
VCC
Z8
X86C64
VSS
12
3819 FHD F03
3
X86C64
MODE SELECTION
CE
V
SS
V
IL
V
IH
V
IH
DS
X
X
V
IL
R/W
X
X
V
IH
V
IL
Mode
Standby
Standby
Read
Write
I/O
High Z
High Z
D
OUT
D
IN
Power
Standby (CMOS)
Standby (TTL)
Active
Active
3819 PGM T08
PAGE WRITE OPERATION
Regardless of the microcontroller employed, the X86C64
supports page mode write operations. This allows the
microcontroller to write from one to thirty-two bytes of
data to the X86C64. Each individual write within a page
write operation must conform to the byte write timing
requirements. The falling edge of
DS
starts a timer
delaying the internal programming cycle 100
µs.
There-
fore, each successive write operation must begin within
100
µs
of the last byte written. The following waveforms
illustrate the sequence and timing requirements.
Page Write Timing Sequence for DS Controlled Operation
OPERATION
BYTE 0
BYTE 1
BYTE 2
LAST BYTE
READ (1)(2)
AFTER tWC READY FOR
NEXT WRITE OPERATION
CE
AS
A/D0–A/D7
AIN
DIN
AIN
DIN
AIN
DIN
AIN
DIN
AIN
DIN
AIN
AIN
A8–A12
A12=n
A12=n
A12=n
A12=n
A12=x
ADDR
Next Address
DS
R/W
tBLC
tWC
3819 FHD
FHD
3819
F07
F07
Notes:
(1) For each successive write within a page write cycle A
5
–A
12
must be the same.
(2) Although it is not illustrated, the microcontroller may interleave read operations between the individual byte writes within the page
write operation. Two responses are possible.
a. Reading from the same plane being written (A
12
of Read = A
12
of Write) is effectively a Toggle Bit Polling operation.
b. Reading from the opposite plane being written (A
12
of Read
≠
A
12
of Write) true data will be returned, facilitating the use of a
single memory component as both program and data store.
4
X86C64
Toggle Bit Polling
Because the X86C64 typical write timing is less than the
specified 5 ms, Toggle Bit Polling has been provided to
determine the early end of write. During the internal
programming cycle I/O
6
will toggle from one to zero and
zero to one on subsequent attempts to read the device.
Toggle Bit Polling
DS
Control
OPERATION
LAST BYTE
WRITTEN
I/O6=X
I/O6=X
I/O6=X
I/O6=X
X68C64 READY FOR
NEXT OPERATION
When the internal cycle is complete the toggling will
cease and the device will be accessible for additional
read or write operations. Due to the dual plane architec-
ture, reads for polling must occur in the plane that was
written; that is, the state of A
12
during write must match
the state of A
12
during polling.
CE
AS
A/D0–A/D7
AIN
DIN
AIN
DOUT
AIN
DOUT
AIN
DOUT
AIN
DOUT
AIN
A8–A12
A12=n
A12=n
A12=n
A12=n
A12=n
ADDR
DS
R/W
3819 FHD F08
5
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