View source for Coprocessor Usable Bits

You do not have permission to edit this page. Log in to edit.
---
title: Coprocessor Usable Bits
type: test
summary: Checks which coprocessor instructions raise an exception when the coprocessor is disabled in SR.
category: Hardware tests
info: Machine = SCPH-5501
info: Program = cpu/cop (ps1-tests)
---

## Overview

Each check sets or clears one coprocessor usable bit in the [COP0](/hardware/cpu/cop0/) status register (SR bits 28 to 31), executes one instruction for that coprocessor and records whether an exception was raised. The instructions are written as words: MFC0 r2,r15 for COP0, the COP1 and COP3 opcodes 44000000h and 4C000000h, MFC2 for the GTE, invalid opcodes 43E00000h and 4BE00000h, and SWC0, SWC2 and SWC3 storing to address 0.[^src]

## Results

The SCPH-5501 passed all 17 checks in every run.[^run]

Table: Exceptions by instruction and SR bit

| Instruction | Coprocessor disabled | Coprocessor enabled |
| --- | --- | --- |
| MFC0 | no exception | no exception |
| COP0 invalid opcode 43E00000h | | no exception |
| SWC0 | exception | no exception |
| COP1 44000000h | exception | no exception |
| MFC2 | exception | no exception |
| COP2 invalid opcode 4BE00000h | | no exception |
| SWC2 | exception | no exception |
| COP3 4C000000h | exception | no exception |
| SWC3 | exception | no exception |

A COP3 instruction with COP3 disabled raised exception code 11 (Coprocessor Unusable).[^run]

## Runs

### 25 September 2026

[04COP.txt](/tests/raw/20260925T0000Z-5501a-card-main/main/04COP.txt)

```
===== 04 COP CPU COP | BIOS 19951204 System ROM Version 3.0 11/18/96 A

cpu/cop
pass - testCop0Disabled
pass - testCop0Enabled
pass - testCop0InvalidOpcode
pass - testSwc0Disabled
pass - testSwc0Enabled
pass - testCop1Disabled
pass - testCop1Enabled
pass - testCop2Disabled
pass - testCop2Enabled
pass - testCop2InvalidOpcode
pass - testSwc2Disabled
pass - testSwc2Enabled
pass - testCop3Disabled
pass - testCop3Enabled
pass - testSwc3Disabled
pass - testSwc3Enabled
pass - testDisabledCoprocessorThrowsCoprocessorUnusable
Done.
```

### 27 September 2026

[04COP.txt](/tests/raw/20260927T0000Z-5501a-card-2/main/s024/04COP.txt)

```
===== 04 COP CPU COP | BIOS 19951204 System ROM Version 3.0 11/18/96 A

cpu/cop
pass - testCop0Disabled
pass - testCop0Enabled
pass - testCop0InvalidOpcode
pass - testSwc0Disabled
pass - testSwc0Enabled
pass - testCop1Disabled
pass - testCop1Enabled
pass - testCop2Disabled
pass - testCop2Enabled
pass - testCop2InvalidOpcode
pass - testSwc2Disabled
pass - testSwc2Enabled
pass - testCop3Disabled
pass - testCop3Enabled
pass - testSwc3Disabled
pass - testSwc3Enabled
pass - testDisabledCoprocessorThrowsCoprocessorUnusable
Done.
```

### 27 September 2026 run 2

[04COP.txt](/tests/raw/20260927T0000Z-5501a-card-b/main/s034/04COP.txt)

```
===== 04 COP CPU COP | BIOS 19951204 System ROM Version 3.0 11/18/96 A

cpu/cop
pass - testCop0Disabled
pass - testCop0Enabled
pass - testCop0InvalidOpcode
pass - testSwc0Disabled
pass - testSwc0Enabled
pass - testCop1Disabled
pass - testCop1Enabled
pass - testCop2Disabled
pass - testCop2Enabled
pass - testCop2InvalidOpcode
pass - testSwc2Disabled
pass - testSwc2Enabled
pass - testCop3Disabled
pass - testCop3Enabled
pass - testSwc3Disabled
pass - testSwc3Enabled
pass - testDisabledCoprocessorThrowsCoprocessorUnusable
Done.
```

### 27 September 2026 run 3

[04COP.txt](/tests/raw/20260927T0000Z-5501a-card-g/main/04COP.txt)

```
===== 04 COP CPU COP | BIOS 19951204 System ROM Version 3.0 11/18/96 A

cpu/cop
pass - testCop0Disabled
pass - testCop0Enabled
pass - testCop0InvalidOpcode
pass - testSwc0Disabled
pass - testSwc0Enabled
pass - testCop1Disabled
pass - testCop1Enabled
pass - testCop2Disabled
pass - testCop2Enabled
pass - testCop2InvalidOpcode
pass - testSwc2Disabled
pass - testSwc2Enabled
pass - testCop3Disabled
pass - testCop3Enabled
pass - testSwc3Disabled
pass - testSwc3Enabled
pass - testDisabledCoprocessorThrowsCoprocessorUnusable
Done.
```

### 27 September 2026 run 4

[04COP.txt](/tests/raw/20260927T0000Z-5501a-card-g3/main/04COP.txt)

```
===== 04 COP CPU COP | BIOS 19951204 System ROM Version 3.0 11/18/96 A

cpu/cop
pass - testCop0Disabled
pass - testCop0Enabled
pass - testCop0InvalidOpcode
pass - testSwc0Disabled
pass - testSwc0Enabled
pass - testCop1Disabled
pass - testCop1Enabled
pass - testCop2Disabled
pass - testCop2Enabled
pass - testCop2InvalidOpcode
pass - testSwc2Disabled
pass - testSwc2Enabled
pass - testCop3Disabled
pass - testCop3Enabled
pass - testSwc3Disabled
pass - testSwc3Enabled
pass - testDisabledCoprocessorThrowsCoprocessorUnusable
Done.
```

### 28 September 2026

[04COP.txt](/tests/raw/20260928T0000Z-5501a-card-h/main/04COP.txt)

```
===== 04 COP CPU COP | BIOS 19951204 System ROM Version 3.0 11/18/96 A

cpu/cop
pass - testCop0Disabled
pass - testCop0Enabled
pass - testCop0InvalidOpcode
pass - testSwc0Disabled
pass - testSwc0Enabled
pass - testCop1Disabled
pass - testCop1Enabled
pass - testCop2Disabled
pass - testCop2Enabled
pass - testCop2InvalidOpcode
pass - testSwc2Disabled
pass - testSwc2Enabled
pass - testCop3Disabled
pass - testCop3Enabled
pass - testSwc3Disabled
pass - testSwc3Enabled
pass - testDisabledCoprocessorThrowsCoprocessorUnusable
Done.
```

## References

[^src]: ps1-tests, cpu/cop. https://github.com/JaCzekanski/ps1-tests.
[^run]: SCPH-5501 output: [main/04COP.txt](/tests/raw/20260925T0000Z-5501a-card-main/main/04COP.txt) and the files beside it, with the other runs listed under Runs.