DS1985 Maxim, DS1985 Datasheet - Page 6

• Manufacturer Part Number: DS1985
• Description: The DS1985 16Kb Add-Only iButton is a rugged read/write data carrier that identifies and stores relevant information about the product or person to which it is attached
• Manufacturer: Maxim

If a Page Address Redirection Byte has a FFH value, the data in the main memory that corresponds to that
page is valid. If a Page Address Redirection Byte has some other hex value, the data in the page
corresponding to that redirection byte is invalid, and the valid data can now be found at the one’s
complement of the page address indicated by the hex value stored in the associated Page Address
Redirection Byte. A value of FDH in the redirection byte for page 1, for example, would indicate that the
updated data is now in page 2. The details for reading and programming the EPROM status memory
portion of the DS1985 are given in the Memory Function Commands section.
DS 1985 MEMORY MAP Figure 4
STATUS MEMORY MAP
REDIRECTION
BYTES
BIT MAP OF
USED PAGES
SCRATCHPAD
WRITE-PROTECT BITS
REDIRECTION BYTES
8-BIT
6 of 26
WRITE-PROTECT BITS
DATA MEMORY
REDIRECTION BYTE FOR PAGE 0, ETC
BIT 0 OF ADDRESS 000H=
ADDRESS 100H=PAGE ADDRESS
WRITE PROTECT
OF PAGE 0, ETC.
88 BYTES
STATUS MEMORY
.