ez80f91 ZiLOG Semiconductor, ez80f91 Datasheet - Page 101

• Manufacturer Part Number: ez80f91
• Description: Ez80 Acclaimplus!? Connectivity Assp Ez80f91 Assp
• Manufacturer: ZiLOG Semiconductor

Random Access Memory
PS027001-0707
The eZ80F91 device features 8 KB (8192 bytes) of single-port data Random Access
Memory (RAM) for general-purpose use and 8 KB of RAM for the EMAC. RAM is
enabled or disabled, and it is relocated to the top of any 64 KB page in memory. Data is
passed to and from RAM via the 8-bit data bus. On-chip RAM operates with zero wait
states. EMAC RAM is accessed via the bus arbiter and executes with zero or one Wait
states.
General purpose RAM occupies memory addresses in the RAM Address Upper Byte reg-
ister in the range
EMAC RAM occupies memory addresses in the range
to
RAM_ADDR_U is set to
this example, RAM_ADDR_U is set to
occupies only a very small fraction of the available 16 MB address space.
When enabled, on-chip RAM assumes priority over on-chip Flash memory and any mem-
ory chip selects that is also enabled in the same address space. If an address is generated in
a range that is covered by both the RAM address space and a particular memory chip
{RAM_ADDR_U[7:0], DFFFh}.
Figure 22. Example: eZ80F91 On-Chip RAM Memory Addressing
7ADFFFh
FFFFFFh
7AFFFFh
7AC000h
7AE000h
000000h
{RAM_ADDR_U[7:0], E000h}
Location
Memory
FFh
.
Figure 22
General-Purpose
EMAC SRAM
Following a RESET, RAM is enabled when
8 KB
RAM
8 KB
7Ah
illustrates a memory map for on-chip RAM. In
.
Figure 22
to
{RAM_ADDR_U[7:0], FFFFh}.
{RAM_ADDR_U[7:0], C000h}
is not drawn to scale, as RAM
RAM_ADDR_U
7Ah
Product Specification
Random Access Memory
eZ80F91 ASSP
93