Motorola MC68HC05RC8 User Manual
Memory
Input/Output Programming
MC68HC05RC16 — Rev. 3.0
General Release Specification
MOTOROLA
Memory
31
2.3.3 RAM
The user RAM consists of 352 bytes of a shared stack area. The RAM
starts at address $0020 and ends at address $017F. The stack begins
at address $00FF. The stack pointer can access 64 bytes of RAM in the
range $00FF to $00C0.
starts at address $0020 and ends at address $017F. The stack begins
at address $00FF. The stack pointer can access 64 bytes of RAM in the
range $00FF to $00C0.
NOTE:
Using the stack area for data storage or temporary work locations
requires care to prevent it from being overwritten due to stacking from an
interrupt or subroutine call.
requires care to prevent it from being overwritten due to stacking from an
interrupt or subroutine call.
2.4 Input/Output Programming
In user mode, 20 lines (28-pin PDIP or 28-pin SOIC) or 24 lines (44-lead
PLCC) are arranged as three 8-bit I/O ports. These ports are
programmable as either inputs or outputs under software control of the
data direction registers. For detailed information, refer to
PLCC) are arranged as three 8-bit I/O ports. These ports are
programmable as either inputs or outputs under software control of the
data direction registers. For detailed information, refer to
.