Rainbow Electronics DS1985 - Manual (Page 6)

DS1985
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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
REDIRECTION
BYTES BIT MAP OF
USED PAGES WRITE-PROTECT BITS
REDIRECTION BYTES WRITE-PROTECT BITS
DATA MEMORY
STATUS MEMORY MAP
BIT 0 OF ADDRESS 000H=
WRITE PROTECT
OF PAGE 0, ETC.
ADDRESS 100H=PAGE ADDRESS
REDIRECTION BYTE FOR PAGE 0, ETC .
8-BIT
SCRATCHPAD
88 BYTES
STATUS MEMORY