Memory Map
Logical and physical address spaces of the PlayStation CPU.
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Overview
The space a program handles is the logical space. A logical address is 32 bits.1
Logical space maps onto physical space several times over. A physical address is an address in the installed memory device.1
Access to a logical address with no physical memory behind it raises a Bus Error exception.1
The R3000 TLB is not present, so the mapping is fixed.2
Physical Memory
Physical memory has a 64MB system area. Main memory ends at 0x1FFFFF on the PlayStation and at 0x7FFFFF on the developer system.2
Segments
Logical space is divided into the following segments:
| Logic Space | Segment title | Cache |
|---|---|---|
| 0x00000000 to physical space MAX | A | Effective |
| 0x1F800000 to 0x1F8003FF | S | Not effective |
| 0x1F801000 to 0x1FBFFFFF | X | Not effective |
| 0x1FC00000 to 0x1FC7FFFF | P | Effective |
| 0x80000000 to 0x80000000 + physical space MAX | B | Effective |
| 0x9FC00000 to 0x9FC7FFFF | Q | Effective |
| 0xA0000000 to 0xA0000000 + physical space MAX | C | Not effective |
| 0xBFC00000 to 0xBFC7FFFF | R | Not effective |
The Cache column refers to the I-cache. A segment is a block of the R3000 memory space and differs from a segment of the 8086 series.1
Devices
The segments map onto the following devices:
| Logic Space | Corresponding Logic Memory Segment | Device |
|---|---|---|
| 0x00000000 to MAX | A+B+C | Main Memory (RAM) |
| 0x1F800000 to 0x1F8003FF | S | Scratchpad (D-cache) |
| 0x1F801000 to 0x1FBFFFFF | X | Hardware Register |
| 0x1FC00000 to 0x1FC7FFFF | P+Q+R | Boot ROM |
Sony does not disclose the addresses inside the OS ROM. Access to the ROM is prohibited.2
The CPU page describes the caches and the scratchpad.