IBM 5150 Technical Reference page 105

Starting Address in Hex
00000 BIOS
Interrupt
Vectors
00080
Available
Interrupt
Vectors
00400
BIOS
Data
Area
00500
User
Read/Write
Memory
caooo
Disk
Adapter
FOOOO
Read
Only
Memory
FEOOO
Bios
Program
Area
BIOS Memory Map
5-12 System BIOS