Internal VS External Attribute Memory Map
The Internal VS External EPROM attribute memory decodes are shown below. This allows the designer to not require an external EPROM device if the single or
nFWE | output | pins | of | the |
SMC91C95 need not be used (if serial EEPROM is being used). Internal to the SMC91C95, the memory addressing logic will allow byte or word on odd byte address access (A0=1), the SMC91C95 will generate an arbitrary value of zero (0) since the PCMCIA specification states that the high byte of a word access in attribute memory is a don’t care. This allows backward compatibility to 8 bit hosts.
Table 7 - Attribute Memory Address Using Serial EEPROM
ATTRIBUTE | EXTERNAL EPROM | INTERNAL SRAM | CONFIGURATION | |
MEMORYADDRESS | STORE | STORE (512 BYTES) | REGISTERS | |
|
|
|
|
|
0 - 3FEh |
| X |
| |
|
|
|
|
|
X |
|
| ||
|
|
|
|
|
8000h - 803Eh |
|
| X | |
|
|
|
|
|
Table 8 - Attribute Memory Address without Serial EEPROM | ||||
|
|
|
|
|
ATTRIBUTE |
| EXTERNAL EPROM | INTERNAL SRAM | CONFIGURATION |
MEMORYADDRESS |
| STORE | STORE (512 BYTES) | REGISTERS |
|
|
|
|
|
0 - 7FFEh |
| X |
|
|
|
|
|
|
|
8000h - 803Eh |
|
|
| X |
|
|
|
|
|
36