Communications Processor
MPC885 PowerQUICC Family Reference Manual, Rev. 2
18-12
Freescale Semiconductor
Figure 18-7. Dual-Port RAM Memory Map
18.7.1
System RAM and Microcode Packages
When optional Freescale-supplied RAM microcode packages are activated, certain portions of the 7-Kbyte
system RAM are no longer available. (The 1-Kbyte parameter RAM is not affected.) Depending on the
memory requirements of the microcode package, some or all of the shaded areas of
Figure 18-7
become
locked. Reads to locked areas return all ones. The unshaded 2-Kbyte (non-contiguous) area of system
RAM is always available to the user.
The enable-RAM-microcode field of the RISC configuration register, RCCR[ERAM], selects the three
possible configurations for microcode area sizes—first 512-byte block, first two 512-byte blocks, or first
four 512-byte blocks. When just the first and/or second 512-byte blocks are used for microcode, an
additional 256-byte extension of system RAM is also locked. When all four 512-byte blocks are used for
microcode, an additional 512-byte extension of system RAM is locked. See the darker-shaded areas of
Figure 18-7
. In addition to RCCR[ERAM], RMDS[ERAM4K] (enable RAM microcode at offset 4K)
affects the system RAM memory configuration for microcode packages. Setting RMDS[ERAM4K] locks
a 2-Kbyte block and a 512-byte extension (the lighter-shaded areas of
Figure 18-7
) for microcode
execution.
0 Kbyte
ERAM = 11
ERAM = 10
ERAM = 01
BD/Data/Microcode
IMMR + 0x2000
1 Kbyte
BD/Data/Microcode
IMMR + 0x2200
BD/Data/Microcode
IMMR + 0x2400
2 Kbyte
BD/Data
IMMR + 0x2800
3 Kbyte
ERAM = 11
BD/Data/Microcode
IMMR + 0x2E00
ERAM = 01, 10
4 Kbyte
IMMR + 0x2F00
ERAM4K = 1
BD/Data/Microcode
IMMR + 0x3000
5 Kbyte
6 Kbyte
BD/Data
IMMR + 0x3800
ERAM4K = 1
7 Kbyte
BD/Data/Microcode
IMMR + 0x3A00
Parameter RAM
Parameters for the
Peripheral
Controllers
IMMR + 0x3C00
8 Kbyte
RCCR[ERAM] governs memory allocation for microcode in dark-shaded areas.
RMDS[ERAM4K] governs memory allocation for microcode in light-shaded areas.
Summary of Contents for PowerQUICC MPC870
Page 98: ...MPC885 PowerQUICC Family Reference Manual Rev 2 I 4 Freescale Semiconductor ...
Page 118: ...MPC885 Overview MPC885 PowerQUICC Family Reference Manual Rev 2 1 20 Freescale Semiconductor ...
Page 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
Page 288: ...MPC885 PowerQUICC Family Reference Manual Rev 2 III 4 Freescale Semiconductor ...
Page 554: ...MPC885 PowerQUICC Family Reference Manual Rev 2 V 6 Freescale Semiconductor ...
Page 1090: ...UTOPIA Interface MPC885 PowerQUICC Family Reference Manual Rev 2 43 8 Freescale Semiconductor ...
Page 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
Page 1336: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 16 Freescale Semiconductor ...
Page 1358: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 38 Freescale Semiconductor ...
Page 1370: ...MPC880 MPC885 PowerQUICC Family Reference Manual Rev 2 E 4 Freescale Semiconductor ...
Page 1386: ...Revision History MPC885 PowerQUICC Family Reference Manual Rev 2 I 2 Freescale Semiconductor ...