act7000asc Aeroflex Circuit Technology, act7000asc Datasheet - Page 12

• Manufacturer Part Number: act7000asc
• Description: Standard Products Act7000asc 64-bit Superscaler Microprocessor
• Manufacturer: Aeroflex Circuit Technology

factor between SysClock and the pipeline clock, the
ACT 7000ASC also allows half-integral multipliers,
thereby providing greater granularity in the designers
choice of pipeline and system interface frequencies.
8 check bits and a 9-bit command bus. In addition, there are
six handshake signals and six interrupt inputs. The
interface has a simple timing specification and is capable of
transferring data between the processor and memory at a
peak rate of 600 MB/sec with a 75 MHz SysClock.
ACT 7000ASC. This example shows a system with a bank
of DRAMs, and an interface ASIC which provides DRAM
control as well as an I/O port.
System Address/Data Bus
transfer addresses and data between the ACT 7000ASC
and the rest of the system. It is protected with an 8-bit parity
check bus, SysADC.
interfacing to memory and I/O systems of varying
frequencies. The data rate and the bus frequency at which
the ACT 7000ASC transmits data to the system interface
are programmable via boot time mode control bits. Also,
the rate at which the processor receives data is fully
controlled by the external device. Therefore, either a low
cost interface requiring no read or write buffering or a
faster, high-performance interface can be designed to
communicate with the ACT 7000ASC. Again, the system
designer
price/performance trade-offs.
System Command Bus
Command (SysCmd) bus. The command bus indicates
whether the SysAD bus carries an address or data. If the
SysAD bus carries an address, then the SysCmd bus also
indicates what type of transaction is to take place (for
example, a read or write). If the SysAD bus carries data,
then the SysCmd bus also gives information about the data
(for example, this is the last data word transmitted, or the
data contains an error). The SysCmd bus is bidirectional to
The interface consists of a 64-bit Address/Data bus with
Figure 6 shows a typical embedded system using the
The 64-bit System Address Data (SysAD) bus is used to
The system interface is configurable to allow easy
The ACT 7000ASC interface has a 9-bit System
SCD7000A Rev B
ACT 7000ASC
has
the
flexibility
Figure 6 – Typical Embedded System Block Diagram
DRAM
to
Latch
SysCmd
72
72
make
SysAD Bus
25
72
these
12
support both processor requests and external requests to the
ACT 7000ASC. Processor requests are initiated by the
ACT 7000ASC and responded to by an external device.
External requests are issued by an external device and
require the ACT 7000ASC to respond.
32-byte block transfers on the SysAD bus. In the case of a
sub-double-word transfer, the 3 low-order address bits give
the byte address of the transfer, and the SysCmd bus
indicates the number of bytes being transferred.
Handshake Signals
Two of these, RdRdy* and WrRdy*, are used by an
external device to indicate to the ACT 7000ASC whether it
can accept a new read or write transaction. The
ACT 7000ASC samples these signals before deasserting
the address on read and write requests.
the SysAD and SysCmd buses from the processor to an
external device. When an external device needs to control
the interface, it asserts ExtRqst*. The ACT 7000ASC
responds by asserting Release* to release the system
interface to slave state.
ACT 7000ASC and the external device respectively to
indicate that there is a valid command or data on the SysAD
and SysCmd buses. The ACT 7000ASC asserts ValidOut*
when it is driving these buses with a valid command or
data, and the external device drives ValidIn* when it has
control of the buses and is driving a valid command or data.
System Interface Operation
an external device, while an external device can issue null
and write requests to the ACT 7000ASC.
ValidOut* and simultaneously drives the address and read
command on the SysAD and SysCmd buses. If the system
interface has RdRdy* asserted, then the processor tristates
its drivers and releases the system interface to slave state by
asserting Release*. The external device can then begin
sending data to the ACT 7000ASC.
Flash /
ROM
Boot
The ACT 7000ASC supports one to eight byte and
There are six handshake signals on the system interface.
ExtRqst* and Release* are used to transfer control of
ValidOut*
The ACT 7000ASC can issue read and write requests to
For processor reads, the ACT 7000ASC asserts
8
Memory I/O
Controller
Address
Control
and
ValidIn*
X
PCI Bus
are
used
X
by
the