Toshiba TLCS-900/H1 Series Data Book page 112

(4) Disappearing Boot-ROM
After Boot-sequence in Boot-mode, an application-system program may continue to run
without reset asserting. In this case, an external-memory which is mapped 3FE000H to 3FFFFFH
address can not be accessed because of Boot-ROM is assigned.
To solve it, internal Boot-ROM can be disappered by setting BROMCR<ROMLESS> to "1".
This <ROMLESS> is initialized to "0" in Boot-mode. At another starting mode, this-register
is initialized to "1".
If this register has been set to "1", writing "0" is disabled.
bit Symbol
Read/Write
BROMCR
After reset
(0167H)
Function
7 6 5
92CH21-108
4 3 2
TMP92CH21
1 0
ROMLESS VACE
R/W
0/1 1/0
Boot-ROM Vector
0: Use Address
1: No-use Conversion
0: disable
1: enable