C501G-1E SIEMENS [Siemens Semiconductor Group], C501G-1E Datasheet - Page 15

• Manufacturer Part Number: C501G-1E
• Description: 8-Bit Single-Chip Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Table 1-1
Pin Definitions and Functions (cont’d)
Symbol
PSEN
RESET
ALE/PROG 33
EA/
Semiconductor Group
*) I
V
O = Output
PP
= Input
P-LCC-44 P-DIP-40 P-MQFP-44
32
10
35
Pin Number
29
9
30
31
26
4
27
29
1-9
I/O*) Function
O
I
I/O
I
The Program Store Enable
output is a control signal that enables the
external program memory to the bus
during external fetch operations. It is
activated every six oscillator periods
except during external data memory
accesses. Remains high during internal
program execution.
RESET
A high level on this pin for two machine
cycles while the oscillator is running
resets the device. An internal diffused
resistor to
using only an external capacitor to
The Address Latch Enable
output is used for latching the low-byte of
the address into external memory during
normal operation. It is activated every six
oscillator periods except during an
external data memory access.
For the C501-1E this pin is also the
program pulse input (PROG) during OTP
memory programming.
External Access Enable
When held at high level, instructions are
fetched from the internal ROM (C501-1R
and C501-1E) when the PC is less than
2000 H . When held at low level, the C501
fetches all instructions from external
program memory. For the C501-L this
pin must be tied low.
This pin also receives the programming
supply voltage
programming (C501-1E) only).
V
SS
permits power-on reset
V
PP
during OTP memory
Introduction
C501
V
CC
.