MC705P6ACPE Datasheet, PDF (19/98 Pages) Freescale Semiconductor, Inc – M68HC05 Microcontrollers

Chapter 2
Memory
2.1 Introduction
The MC68HC705P6A utilizes 13 address lines to access an internal memory space covering 8 Kbytes.
This memory space is divided into I/O, RAM, ROM, and EPROM areas.
2.2 User Mode Memory Map
When the MC68HC705P6A is in the user mode, the 32 bytes of I/O, 176 bytes of RAM, 4608 bytes of user
EPROM, 48 bytes of user page zero EPROM, 239 bytes of bootloader ROM, and 16 bytes of user vectors
EPROM are all active as shown in Figure 2-1.
2.3 Bootloader Mode Memory Map
Memory space is identical to the user mode. See Figure 2-1.
2.4 Input/Output and Control Registers
Figure 2-2 and Figure 2-3 briefly describe the I/O and control registers at locations $0000–$001F.
Reading unimplemented bits will return unknown states, and writing unimplemented bits will be ignored.
2.5 RAM
The user RAM consists of 176 bytes (including the stack) at locations $0050 through $00FF. The stack
begins at address $00FF. The stack pointer can access 64 bytes of RAM from $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.
2.6 EPROM/ROM
There are 4608 bytes of user EPROM at locations $0100 through $12FF, plus 48 bytes in user page zero
locations $0020 through $004F, and 16 additional bytes for user vectors at locations $1FF0 through
$1FFF. The bootloader ROM and vectors are at locations $1F01 through $1FEF.
MC68HC705P6A Advance Information Data Sheet, Rev. 2.1
Freescale Semiconductor
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