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ST63126 View Datasheet(PDF) - STMicroelectronics

Part Name
Description
MFG CO.
'ST63126' PDF : 86 Pages View PDF
ST63140,142,126,156
MEMORY SPACES (Continued)
Figure 11. Program ROM Page Register
PRPR
Program ROM Page Register
(CAh, Write Only)
D7 D6 D5 D4 D3 D2 D1 D0
PRPR0 = PROG.ROM Select 0
PRPR1 = PROG.ROM Select 1
UNUSED
UNUSED
UNUSED
UNUSED
UNUSED
UNUSED
Care is required when handling the PRPR as it is
write only. For this reason, it is not allowed to
change the PRPR contents while executing inter-
rupts drivers, as the driver cannot save and than
restore its previous content. Anyway, this opera-
tion may be necessary if the sum of common rou-
tines and interrupt drivers will take more than 2K
bytes; in this case could be necessary to divide the
interrupt driver in a (minor) part in the static page
(start and end), and in the second (major) part in
one dynamic page. If it is impossible to avoid the
writing of this register in interrupts drivers, an im-
age of this register must be saved in a RAM loca-
tion, and each time the program writes the PRPR it
writes also the image register. The image register
must be written first, so if an interrupt occurs be-
tween the two instructions the PRPR is not af-
fected.
D7-D2. These bits are not used.
PRPR1-PRPR0. These are the program ROM
banking bits and the value loaded selects the cor-
responding page to be addressed in the lower part
of 4K program address space as specified in Table 3.
This register is undefined on reset.
Note:
Only the lower part of address space has been
bankswitched because interrupt vectors and com-
mon subroutines should be available all the time.
The reason of this structure is due to the fact that it
is not possible to jump from a dynamic page to an-
other, unless jumping back to the static page,
changing contents of PRPR, and, then, jumping to
a different dynamic page.
Table 3. Program ROM Page Register Coding
PRPR1 PRPR0
X
X
0
0
0
1
1
0
1
1
PC11
1
0
0
0
0
Memory Page
Static Page (Page1)
Page 0
Page 1 (Static Page)
Page 2
Page 3
This register is undefined on reset. Neither
read nor single bit instructions may be used to
address this register.
Table 4. ST631xx Program ROM Map
ROM Page
Device Address
Device Address (1)
PAGE 0
0000h-007Fh
0080h-07FFh
0000h-007Fh
0080h-07FFh
PAGE 1
“STATIC”
0800h-0F9Fh
0FA0h-0FEFh
0FF0h-0FF7h
0FF8h-0FFBh
0FFCh-0FFDh
0FFEh-0FFFh
0800h-0F9Fh
0FA0h-0FEFh
0FF0h-0FF7h
0FF8h-0FFBh
0FFCh-0FFDh
0FFEh-0FFFh
PAGE 2
0000h-000Fh
0010h-07FFh
1000h-100Fh
1010h-17FFh
PAGE 3
0000h-000Fh
0010h-07FFh
1800h-180Fh
1810h-1FFFh
Note 1. EPROM addresses relate to the use of ST63E1xx EPROM Emulation device.
Description
Reserved
User ROM
User ROM
Reserved
Interrupt Vectors
Reserved
NMI Vector
Reset Vector
Reserved
User ROM
Reserved
User ROM
11/82
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