CORE
Architectural channels, WAIT/TAKE, process state, scheduler and architectural IN/OUT.
Project / T425-SIM
T425-SIM
In test
Overall project status: IN_TEST. A closed subsystem checkpoint does not establish complete T425 compatibility.
Architectural baseline
The project keeps an explicit separation between the conceptual processor path and platform-specific transport. The map is an audited architectural path, not a claim of complete compatibility.
Processes express intent and exchange messages.
Audited architectural path
The documented baseline includes the following architectural areas. This list is evidence of an audited path, not proof of a complete IMS T425 implementation.
- Instruction/opcode and OReg processing
- CROM entry
- 118-bit MIR
- Datapath
- Condition selection
- NEXTMPC / microsequencing
- Scheduler/process semantics
- Timers
- Channel semantics
CORE ↔ Link Service ↔ PHY
The boundary assigns responsibility without collapsing architectural semantics into hardware details.
LINK SERVICE
Transport abstraction and endpoint routing between logical processor/channel behavior and physical transport.
PHY
PIO/FIFO/IRQ/DMA mechanisms where applicable, physical per-link state, token/event attribution and physical DATA/ACK behavior. Physical ACK remains PHY-local.
Validated PHY checkpoint
The project documentation records this PHY checkpoint as validated. It is deliberately narrower than the overall project status.
- Four full-duplex physical links
- Two PIO state machines per link; eight PIO state machines total
- Endpoint 0..3 maps to architectural Link0..3 only at the CORE-PHY seam
- Physical ACK per DATA byte remains PHY-local
- One outstanding DATA byte per direction
- Outgoing ACK bypasses DATA wait
- Portable CORE has no RP2040/PIO/DMA/GPIO dependency
- RX admission is controlled by CORE architectural state
- External IN lifetime is explicit
- Multibyte RX credit is rearmed one byte at a time
- N+1 remains unaccepted/unACKed until another architectural IN
Outside this checkpoint
The following remain outside the cited PHY validation and are future or still-open work:
Work outside the validated PHY checkpoint
- VM
- OCCAM execution and integration
- Helios integration
- Remaining system-service behavior not closed by the cited PHY work
System-service behavior not claimed by this checkpoint
- Error / ErrorIn
- Analyse / HaltOnError
- EventReq / EventAck / EventWaiting
- ProcSpeedSelect
- DisableIntRAM