29 MISC REGISTERS (MISC)
29-6
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
By default (IVRAM_LOC = 1), IVRAM is located in Area 3 and is used as the internal VRAM.
Setting IVRAM_LOC to 0 relocate IVRAM in Area 0 and it can be used as a general-purpose RAM. In
this case, 20KB IVRAM follows 12KB IRAM.
Note: When IVRAM is switched to Area 0 or Area 3, the contents of IVRAM may be destroyed.
Therefore, write data to IVRAM after the location is changed.
Misc Protect Register (MISC_PROTECT)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
Misc Protect
Register
(MISC_
PROTECT)
0x300020
(8 bits)
D7–0 PROT[7:0] Misc register write-protect flag
Writing 10010110 (0x96)
removes the write protection of
the Misc registers (0x300010–
0x300018).
Writing another value set the
write protection.
0x0 R/W
D[7:0]
PROT[7:0]: Misc Register Write-Protect Flag Bits
Enables or disables write protection of the Misc registers (0x300010–0x300018).
0x96 (R/W):
Disable write protection
Other than 0x96 (R/W): Write-protect the register (default: 0x0)
Before altering any Misc register from 0x300010 to 0x300018, write data 0x96 to PROT[7:0] to disable
write protection. If PROT[7:0] is set to other than 0x96, even if an attempt is made to alter any Misc
register by executing a write instruction, the content of the register will not be altered even though the
instruction may have been executed without an error. Once PROT[7:0] is set to 0x96, the Misc registers
can be rewritten any number of times until being reset to other than 0x96. When rewriting the Misc reg-
isters has finished, PROT[7:0] should be set to other than 0x96 to prevent accidental writing to the Misc
registers.