GMS90C320
Pin Number
P-DIP-40
Input/
Output
Symbol
Function
P-MQFP-
44
P-LCC-44
P2.0-P2.7
24-31
21-28
18-25
I/O
Port 2
Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. Port 2
pins that have 1s written to them are pulled high by the internal
pull-up resistors and can be used as inputs. As inputs, port 2 pins
that are externally pulled low will source current because of the
pulls-ups (IIL, in the DC characteristics). Port 2 emits the high-
order address byte during fetches from external program memory
and during accesses to external data memory that use 16-bit
addresses (MOVX @DPTR). In this application it uses strong
internal pull-ups when emitting 1s. During accesses to external
data memory that use 8-bit addresses (MOVX @Ri), port 2 emits
the contents of the P2 special function register.
PSEN
32
29
26
O
The Program Store Enable
The read strobe to external program memory when the device is
executing code from the external program memory. PSEN is acti-
vated twice each machine cycle, except that two PSEN activation
are skipped during each access to external data memory. PSEN
is not activated during fetches from internal program memory.
RESET
ALE
10
33
9
4
I
RESET
A high level on this pin for two machine cycles while the oscillator
is running resets the device. An internal diffused resistor to VSS
permits power-on reset using only an external capacitor to VCC
.
30
27
O
The Address Latch Enable
Output pulse for latching the low byte of the address during an
access to external memory. In normal operation, ALE is emitted
at a constant rate of 1/6 the oscillator frequency, and can be used
for external timing or clocking. Note that one ALE pulse is skipped
during each access to external data memory.
EA
35
31
29
I
External Access Enable
EA must be external held low to enable the device to fetch code
from external program memory locations 0000H to FFFFH. If EA is
held high, the device executes from internal program memory
unless the program counter contains an address greater than its
internal memory size.
P0.0-P0.7
43-36
39-32
37-30
I/O
Port 0
Port 0 is an 8-bit open-drain bidirectional I/O port. Port 0 pins that
have 1s written to them float and can be used as high-impedance
inputs. Port 0 is also the multiplexed low-order address and data
bus during accesses to external program and data memory. In
this application it uses strong internal pull-ups when emitting 1s.
Port 0 also outputs the code bytes during program verification in
the GMS97C5x. External pull-up resistors are required during
program verification.
VSS
VC C
22
44
20
40
16
38
-
-
-
Circuit ground potential
Supply terminal for all operating modes
No connection
N.C.
1,12,
23,34
6,17,
28,39
-
OCT. 2000 Ver 1.2
7
HYNIX [ HYNIX SEMICONDUCTOR ]
