Maxim Integrated High-Speed Microcontroller - Manual (Page 42)

High-Speed Microcontroller User’s Guide
Rev: 062210 42 of 176
4.2.31 ROM Size Select (ROMSIZE)
7 6 5 4 3 2 1 0
SFR C2h — — — — — RMS2 RMS1 RMS0
RT-1 RT-0 RT-1
R = Unrestricted Read, W = Unrestricted Write, -n = Value after Reset
Bits 7–3 These bits are reserved. Read data is indeterminate.
RMS2, RMS1,
RMS0
Bits 2, 1, 0 ROM Size Select 2-0. This register is used to select the maximum on-chip decoded
address for ROM. Care must be taken that the memory location of the current program
counter will be valid both before and after modification. These bits can only be
modified using a timed access procedure. The
EA pin will override the function of these
bits when asserted, forcing the device to access external program memory only.
Configuring this register to a setting that exceeds the maximum amount of internal
memory may corrupt device operation. These bits will default on reset to the maximum
amount of internal program memory (i.e., 16kB for DS87C520).
RMS2 RMS1 RMS0 MAXIMUM ON-CHIP ROM ADDRESS
0 0 0 0kB/Disable on-chip ROM
0 0 1 1kB/03FFh
0 1 0 2kB/07FFh
0 1 1 4kB/0FFFh
1 0 0 8kB/1FFFh
1 0 1 16kB/3FFFh
1 1 0 132kB/7FFFh
1 1 1 64kB/FFFFh