80C88_04 Datasheet, PDF (14/32 Pages) Intersil Corporation – CMOS 8/16-Bit Microprocessor

80C88
The 80C88 and 80C86 are completely software compatible
by virtue of their identical execution units. Software that is
system dependent may not be completely transferable, but
software that is not system dependent will operate equally as
well on an 80C88 or an 80C86.
The hardware interface of the 80C88 contains the major
differences between the two CPUs. The pin assignments are
nearly identical, however, with the following functional
changes:
• A8-A15: These pins are only address outputs on the
80C88. These address lines are latched internally and
remain valid throughout a bus cycle in a manner similar to
the 8085 upper address lines.
• BHE has no meaning on the 80C88 and has been elimi-
nated.
• SS0 provides the S0 status information in the minimum
mode. This output occurs on pin 34 in minimum mode
only. DT/R, IO/M and SS0 provide the complete bus status
in minimum mode.
• IO/M has been inverted to be compatible with the 8085
bus structure.
• ALE is delayed by one clock cycle in the minimum mode
when entering HALT, to allow the status to be latched with
CLK
T1
T2
T3
T4
80C88
QS1, QS0
S2, S1, S0
A19/S6 - A16/S3
ALE
A19 - A16
S6 - S3
80C88
RDY 82C84
READY 80C88
AD7 - AD0
DATA OUT
A7-A0
80C88
A15 - A8
RD
DT/R
DATA IN
A15 - A8
80C88 MRDC
DEN
FIGURE 21. MEDIUM COMPLEXITY SYSTEM TIMING
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