Device
and operation
CPC307
C P C 3 0 7 U s e r M a n u a l
31
© 2 0 2 2 F a s t w e l v . 0 0 6
4.2 Address Space Allocation
4.2.1 Address space allocation
Table 4.1. Address space allocation of the first megabyte of memory
Range of addresses
Size
Description
00000h
– 9FFFFh
640 KB
RAM
A0000h
– BFFFFh
128 KB
PCI/ISA VGA Graphics
C0000h
– С7FFFh
32 KB
VGA BIOS
C8000h
– CFFFFh
32 KB
Expansion Card Boot ROM
D0000h - EFFFFh
128 KB
Not USED
F0000h
– FFFFFh
64 KB
BIOS
4.2.2 I/O address space allocation
Table 4.2. I/O address space allocation
Range of
addresses
Function
Note
0000h
– 001Fh
8237 DMA Controller #1
–
0020h
– 0021h
8259 Master Interrupt Controller
–
0022h
– 0023h
Indirect Access
WDT0
0024h
– 002Dh
ISA bus
Access to external bus
002Eh
– 002Fh
Reserved
Not available
0030h
– 003Fh
ISA bus
Access to external bus
0040h
– 0043h
8253 Programmable Timer
–
0044h
– 0047h
ISA bus
Access to external bus
0048h
– 004Bh
Reserved
Not available
004Eh
– 005Fh
ISA bus
Access to external bus
0060h
– 0064h
8042 Keyboard Controller
–
0065h
WDT0
–
0066h
ISA bus
Access to external bus
0067h
– 006Dh
WDT1
–
006Eh
– 006Fh
ISA bus
Access to external bus
0070h
– 007Fh
RTC, NMI Mask Register
–
0080h
– 009Fh
DMA Page Registers
–
00A0h
– 00B1h
8259 Slave Interrupt Controller
–