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14-9
PROGRAMMING AND VERIFYING NONVOLATILE MEMORY
14.7 VERIFYING THE 83C251SA, SB, SP, SQ (ROM)
Nonvolatile memory on the 83C251Sx controller is factory-programmed. The verification proce-
dure for the 83C251Sx is exactly the same as for the 87C251Sx. The setup shown in Figure 14-1
applies, as do the waveform and timing diagrams. Like the 87C251Sx, the 83C251Sx has 8-
Kbytes or 16-Kbytes of on-chip code memory and a 128-byte encryption array.
For information on verifying the contents of nonvolatile memory on the 83C251Sx, see 14.6,
“Programmable Functions” for each function desired. Or more directly, perform the verification
procedure described in 14.5, “Verify Algorithm,” using the appropriate verify mode (Table 14-1).
Table 14-3. Contents of the Signature Bytes
ADDRESS CONTENTS DEVICE TYPE
30H 89H Indicates Intel Devices
31H 40H Indicates MCS 251 core product
60H 7AH Indicates 83C251SA device
60H 7BH Indicates 83C251SB device
60H 4AH Indicates 83C251SP device
60H 4BH Indicates 83C251SQ device
60H FAH Indicates 87C251SA device
60H FBH Indicates 87C251SB device
60H CAH Indicates 87C251SP device
60H CBH Indicates 87C251SQ device
61H 55H Indicates 8XC251SA, SB, SP, SQ