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Implemented faults and fault handling.

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Added flags FLTSTS, FLTJH, FLTJL.

Added breakpoints and BRK instruction.

Added PUSH and POP instructions for interacting with the stack.
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Sam Stevens
2017-12-31 23:18:17 +00:00
parent bd3a4d5491
commit cf9004e206
27 changed files with 547 additions and 45 deletions
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46
FLAGS.md
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@@ -2,9 +2,9 @@
Locations shown below are relative to the start of flags, typically 0xFF00.
Bits marked N/A read as zero and writing values will not have an effect.
Bits not defined read as zero and writing values will not have an effect.
## Console
## Console | 0x0*
### Status | CONSTS | 0x00
@@ -12,7 +12,7 @@ Bits marked N/A read as zero and writing values will not have an effect.
| --------------- | --- | --- | --- | --- | --- | --- | --- | --- |
| **Read/Write** | | | | | R | R/W | R/W | R |
| **Default ** | | | | | X | 1 | 1 | X |
| **Name** | N/A | N/A | N/A | N/A | ReadAvailable | ReadBlock | Enabled | Available |
| **Name** | | | | | ReadAvailable | ReadBlock | Enabled | Available |
### Cursor X | CONPOSX | 0x01
@@ -34,17 +34,47 @@ Bits marked N/A read as zero and writing values will not have an effect.
* 8-bit unsigned number
* Read/Write
## ALU
## Interrupts/Faults | 0x1*
Faults can be caught and handled by specifying a jump location in FLTRH and FLTRL. This handler must clear FLTSYS/2, it may call RET to continue execution or jump elsewhere.
### Fault Status | FLTSTS | 0x10
| | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 |
| --------------- | --- | --- | --------------- | --------------- | ---------- | ------------ | ---- | --- |
| **Read/Write** | | | R | R | R | R | R/W | R/W |
| **Default ** | | | X | X | X | X | X | 0 |
| **Name** | | | Memory Overflow | Stack Exceeded | Illegal Op | Undefined Op | Trip | Enabled |
If not enabled, the system will halt should a fault occur.
In a fault condition, only one type will be indicated.
Clearing **Trip** will clear status bits 3-8, it cannot be set.
If a second fault occurs before trip is cleared, the system will halt; this known as a double-fault.
**Undefined Op** indicates an operation that was unknown. **Illegal Op** indicates that the parameters to the operation were not valid.
**Stack Exceeded** Indicates that the stack either overflowed (PUSH or CALL when full) or underflowed (RET or POP when empty). In this condition the stack pointer is reset to 0.
### Fault Routine High Byte | FLTJH | 0x11
The high byte of the fault handler jump.
### Fault Routine Low Byte | FLTJL | 0x12
The low byte of the fault handler jump.
## ALU | 0x2*
Flags here for logic/math results
## Tape
## Tape | 0x3*
Tape control and status
## Traps
Trap status and settings
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