sh6636 SinoWealth Micro-Electronics Corp. Ltd, sh6636 Datasheet - Page 5

• Manufacturer Part Number: sh6636
• Description: Mask 4-bit Microcontroller With Remote Control Carrier Synthesizer
• Manufacturer: SinoWealth Micro-Electronics Corp. Ltd

3. ROM
The SH6636 can address 24K X 16 bit words of program area from $0000 to $5FFF.
ROM SPACE in the system is 24576 X 16 bits.
(a) Vector Address Area ($000 to $004)
The program is sequentially executed. There is an area address $000 through $004 that is reserved for a special interrupt
service routine such as starting vector address.
(b) Table Data Reference
Table Data can be stored in the program memory and can be referenced by using the Table Branch (TJMP) and the Return
Constant (RTNW) instructions. The Table Branch Register (TBR) and Accumulator (A) are placed by an offset address in
program ROM. TJMP instruction branch into address ((PC11 - PC8) X (2
return look-up value into (TBR, A). ROM code bit7-bit4 is placed into TBR and bit3-bit0 into A.
(c) Bank Switch Mapping
Program Counter (PC11 - PC0) can only address 4K ROM space. The bank switch technique is used to extend the CPU
address space. The lower 2K of the CPU address space maps to the lower 2K of ROM space (BANK0). The upper 2K of the
CPU address space maps to one of the fifteen banks (BNK 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A) of the upper 22K of ROM. (according
to the Bank Register)
The bank switch mapping is as follows:
000 - 7FF
800 - FFF
000 - 7FF
800 - FFF
Address
Address
CPU
CPU
Address
$000H
$001H
$002H
$003H
$004H
ROM Space,
ROM Space,
0000 - 07FF
0800 - 0FFF
0000 - 07FF
4000 - 47FF
(BANK 0)
(BANK 1)
(BANK 0)
(BANK 8)
BNK = 0
BNK = 7
ROM Space,
ROM Space,
0000 - 07FF
1000 - 17FF
0000 - 07FF
4800 - 4FFF
(BANK 0)
(BANK 2)
(BANK 0)
(BANK 9)
BNK = 1
BNK = 8
Instruction
NOP
NOP
JMP
JMP
JMP
ROM Space,
ROM Space,
1800 - 1FFF
0000 - 07FF
0000 - 07FF
5000 - 57FF
(BANK 10)
(BANK 0)
(BANK 3)
(BANK 0)
BNK = 2
BNK = 9
ROM Space,
ROM Space,
0000 - 07FF
2000 - 27FF
0000 - 07FF
5800 - 5FFF
5
(BANK 11)
(BANK 0)
(BANK 4)
(BANK 0)
BNK = A
BNK = 3
Jump to RESET service routine
Reserved
Jump to TIMER0 service routine
Reserved
Jump to PBC service routine
8
) (TBR, A)). The address is determined by RTNW to
ROM Space,
0000 - 07FF
2800 - 2FFF
(BANK 0)
(BANK 5)
BNK = 4
Function
ROM Space,
0000 - 07FF
3000 - 37FF
(BANK 0)
(BANK 6)
BNK = 5
ROM Space,
3800 - 3FFF
0000 - 07FF
(BANK 0)
(BANK 7)
SH6636
BNK = 6