Pin Descriptions
MU9C RCP Family
PA3-0 (Page Address, Output)
/AV (Address Valid, Input)
The PA3-0 lines convey Page Address information. When
the /OE input is HIGH, the PA3-0 outputs are in their
high-impedance state; when /OE is LOW the PA3-0 lines
carry the Page Address value held in the Configuration
register. The PA3-0 lines are latched when /E is LOW, and
are free to change only when /E is HIGH. The Page
Address value of the currently active or highest-priority
responding device is output at the same time, and under
the same conditions, as the AA bus is active.
When Hardware control is selected, the /AV input
determines whether the AC bus carries address or control
information. When /AV is LOW, the AC bus conveys a
memory address; when /AV is HIGH, the AC bus conveys
control information. The state of the /AV line is registered
by the falling edge of /E. When software control is
selected, the /AV line distinguishes between instructions
and data on the DQ31-0 lines; when /AV is LOW, data is
present on the DQ31-0 lines; when /AV is HIGH, an
instruction is present on the DQ11-0 lines.
/E (Chip Enable, Input)
/VB (Validity Bit, Three-state, Common Input/
Output)
The /E input is the main chip enable and synchronizing
control for the MU9C RCP. When /E is HIGH, the chip is
disabled and the DQ31-0 lines are held in their
high-impedance state. The falling edge of /E registers the
/W, /CS1, /CS2, /AV, /AC bus, DSC, and the /VB and
DQ31-0 lines for a Write cycle. /E being LOW causes the
results of the previous comparison or memory access to be
latched on the PA:AA bus; when /E goes HIGH the latches
open allowing the new comparison results or random
access memory address to flow to the PA:AA bus.
During accesses over the DQ31-0 lines, the /VB line
conveys validity information to and from the MU9C RCP.
During a Write cycle (/W=LOW), when /VB is LOW the
addressed location is set valid; when /VB is HIGH it is set
empty. During a Read cycle (/W=HIGH), the validity of
the addressed location is read on the /VB line. During a
Write cycle, the state of the /VB line is registered by the
falling edge of /E.
/CS1, /CS2 (Chip Select 1, Chip Select 2,
Inputs)
/MF (Match Flag, Output)
The /MF output indicates whether a valid match has
occurred during the previous Comparison cycle. If the
/MF output is HIGH at the end of a Comparison cycle,
then no match occurred; if it is LOW then either a match
occurred within the device, or the /MI input is LOW,
conditioned by the /MF output from a higher-priority
device in the system. The state of the /MF line will not
change until after the rising edge of /E during the
Comparison cycle. Note that /MF indicates the results of
the most recent Comparison cycle; it will not change when
the PA:AA bus carry an address other than the Match
address.
The /CS1 and /CS2 inputs enable the MU9C RCP. If either
/CS1 or /CS2 are LOW, the device is selected for a Read,
Write, or Compare cycle through the DQ31-0 lines, or for
an internal data transfer. The /CS1 and /CS2 lines do not
have any effect on the PA:AA bus. The state of the /CS1
and /CS2 lines is registered by the falling edge of /E.
/W (Write Enable, Input)
The /W input determines the direction of data transfer on
the DQ31-0 lines during Read, Write, and Data Move
cycles. When /W is LOW, data flows into the DQ31-0
lines; when /W is HIGH, data flows out. The /W line also
conditions the control state present on the AC bus and
DSC lines. The state of the /W line is registered by the
falling edge of /E.
/MI (Match Input, Input)
The /MI input receives match information from the next
higher-priority MU9C RCP in a vertically cascaded
system to provide system-level prioritization. When the
/MI input is HIGH, the /MF output will only go LOW if
there is a match during a Comparison cycle; when the /MI
input is LOW, the /MF output will go LOW. The /MF
output from one device is connected to the /MI input of the
next lower-priority device. The /MI pin of the
highest-priority device must be tied HIGH.
/OE (Output Enable, Input)
The /OE input enables the PA:AA bus. When /OE is
HIGH, PA:AA bus are in their high-impedance state.
When /OE is LOW, PA:AA bus are active, and convey the
results of the last Comparison Cycle Match address or
Memory Access address. In a vertically cascaded system,
only the PA:AA bus of the highest-priority device will be
activated by /OE being LOW; in lower-priority devices,
the PA:AA bus remains in high-impedance regardless of
the state of /OE.
Rev. 8.04
5
MUSIC [ MUSIC SEMICONDUCTORS ]
