harness: level-1 VIDEO MEMORY test passes (video RAM mapped + REFCNT advances); next gate is HOST PORT

debug.log

@@ -1,7 +1,15 @@
 MAME debugger version 0.289 (mame0289-dirty)
 Currently targeting vt1200 (VT1200 X terminal (v2.2 firmware))
 Breakpoint 1 set
-DISPATCH sp=00005280 w=00001580 00000000 00000001 3FDF8A20 000016B0 00001560 00000000 00000000
+PRINT pc=3FDE00C0 a9=3FDCA8E8 a11=0040000C a5=00000000
 
-DISPATCH sp=00005280 w=00001580 00000100 00000000 3FDF90E0 000016B0 00001560 00000000 00000000
+PRINT pc=3FDE00C0 a9=3FDC9C68 a11=00000015 a5=00000000
+
+PRINT pc=3FDE00C0 a9=0080000C a11=00000015 a5=00000000
+
+PRINT pc=3FDE00C0 a9=00C0000C a11=00000015 a5=00000000
+
+PRINT pc=3FDE00C0 a9=0100000C a11=00000015 a5=00000000
+
+PRINT pc=3FDE00C0 a9=0200000C a11=00000015 a5=00000000
 

ghidra/vt1200.lock

@@ -1,9 +1,9 @@
 #Ghidra Lock File
-#Fri Oct 16 10:37:43 EEST 2026
+#Fri Oct 16 10:54:50 EEST 2026
 <META>\ Supports\ File\ Channel\ Locking=Channel Lock
 Hostname=sid
 OS\ Architecture=amd64
 OS\ Name=Linux
 OS\ Version=7.2.4-arch1-2
-Timestamp=10/16/26, 10\:37\u202FAM
+Timestamp=10/16/26, 10\:54\u202FAM
 Username=arti

harness/mame/BRINGUP_LOG.md

@@ -927,49 +927,63 @@ one `0xffe0` reference in the routine, the read in the dispatcher, so the code i
 locally). The failing code is therefore chosen by **whatever calls this routine** — and that
 caller is what still needs finding.
 
+## MILESTONE: the level-1 VIDEO MEMORY test now PASSES (2026-10-16)
+
+The code-22 investigation (`harness/mame/CODE22_REPORT.md`) found exactly what the test
+requires, and two changes satisfy it. **The firmware has moved on to the next level-1 test.**
+
+### What raises code 22 (in the firmware's own terms)
+
+```
+level-1 video-memory self-test at bit 0x3F2018B0   (base 0x04000000, count 0x20000)
+   returns non-zero  ->  L3FA7C050  ->  code 0x100 stored at 0x3FA7DE30
+   ->  dispatcher 0x3FDF0630  ->  the VIDEO MEMORY - 22 handler
+```
+
+Its failing condition depended on configuration, which turned out to be two separate bugs:
+
+1. **Default driver:** the 16-bit walking-bit read-back at `0x04000000` returns 0 because
+   **video RAM is unmapped** -> fixed by mapping it (`VT1200_VRAM=1`, base bit `0x04000000`).
+2. **With video RAM mapped:** the pattern walk then *passes*, and the failure moved to the
+   **REFCNT check at `0x3F201ED0`** — `0xC00001F0` returned the **same value twice**, which
+   the firmware treats as an error (`a8=0x0E`).
+
+### The REFCNT fix (a local MAME core change — revert note included)
+
+MAME modelled the refresh counter too coarsely:
+
+```cpp
+case REG_REFCNT:
+    return (total_cycles() / 16) & 0xfffc;   // changes only every 64 cycles
+```
+
+The test reads REFCNT twice a few instructions apart and requires the value to have moved.
+Changed in `/home/arti/code/k-space/mame0289/src/devices/cpu/tms34010/tms34010.cpp` to
+`return total_cycles() & 0xffff;`, with the original line preserved in a comment directly
+above it for reverting. **This is a local change to the emulator, not to anything DEC made** —
+the ROM is untouched, and the change makes the emulator's refresh counter behave the way the
+firmware is probing for.
+
+### Result
+
+With video RAM mapped and REFCNT advancing:
+
+```
+error-22 prints: 0                      <- the video-memory test PASSES
+next failure:    'LEVEL1/2 ERROR -> HOST PORT - 15 '
+```
+
+### Where it stands now
+
+The level-1 sequence has advanced to the **HOST PORT** test — DUART1 channel A, per the
+service guide's "Host port test". The DUARTs are not modelled at all, so that is the next
+gate. The shape of the work is now established and repeatable: identify the test, find the
+condition it fails on, model it, re-run the console capture.
+
 ---
 
 ## Next steps
 
-1. Find the CALLER of FUN_rom_07fbd000 and the status code it passes -- that is the
-   failing test.  Use smart34010 for call targets (Ghidra's CALLA does not resolve).
-2. Optionally fix Ghidra's CALLA operand handling to get a usable call graph.
-
-## Where the level-1 investigation stands (2026-10-16, end of this stretch)
-
-**Not solved: level 1 still fails, no picture.**
-
-Solid and committed (these do not need redoing):
-
-* **Address units** — from MAME's source: the TMS34010 program space is
-  `memory_access<32,1,3>`, so map units are **bits** and bytes = bit >> 3; a handler on an
-  entry at `base` receives `(bitaddr - base) >> 4`. Precedence is plain last-wins.
-* **Instruments** — the catch-all is trustworthy (closed cross-check: moving a probe to the
-  right address shifted exactly 183,536 accesses out of it). `VT1200_BOARD_LOG`,
-  `VT1200_LOG_UNMAPPED`, `VT1200_CAL`, `VT1200_VRAMLOG` all work. **Watchpoints do not work
-  headless**; `bpset` does.
-* **Video memory** — located at bit `0x04000000` (~110 KiB first bank), mapped, and proven to
-  round-trip a walking-bit pattern. It is **not** the missing piece: the test still fails
-  with it mapped and round-tripping.
-* **The level-1 video RAM test** — characterised: a walking-bit data-bus test (8,208 writes,
-  8,208 read-backs, 4,096 offsets).
-* **Console capture** — `cap.lua`, breaking at the printer `3FDE00C0` and logging `a9`/`a11`,
-  gives the firmware's own self-test narration.
-* **Ghidra** — project seeded and saved (25 functions) and it cross-validates `smart34010`
-  instruction-for-instruction. Caveat: **Ghidra's `CALLA` targets do not resolve**, so its
-  call graph is empty — use `smart34010` for call targets.
-
-Withdrawn after being shown wrong: "the test fails at bit 0x040000C0" (the value came from a
-stale register; the error strings are selected by a **status code**, and the numbers printed
-with them are message constants, not addresses).
-
-**The open question, stated cleanly:** which level-1 test raises status code 22 (video
-memory), and what condition makes it raise it. The error dispatcher is
-`FUN_rom_07fbd000` (Ghidra `0x07FBD000`-`0x07FBE201`), it takes the code as an argument, and
-the stack at the dispatcher shows the **error-reporting framework**, not the test that
-produced the code — so the test must be found another way.
-
-**Suggested next approach** (not yet tried): intercept where the status code is *stored*
-rather than where it is consumed — the framework keeps the code in a global, so watch the
-global for transitions to 22 and take the PC there. That would land inside the failing test
-directly.
+1. Model the host DUART (DUART1 channel A) enough for the level-1 HOST PORT test
+   (bit 0x3F...); the DUARTs are unmodelled and are the current gate.
+2. Keep using cap.lua to read which test fails next -- the loop is now repeatable.

tools/ghidra-tms34010/tms34010.sinc

@@ -70,7 +70,7 @@ addr5: fwd is bits_5_9 & bits_10 = 0 [fwd = inst_next + (bits_5_9 * 2);] {export
 addr5: bwd is bits_5_9 & bits_10 = 1 [bwd = inst_next - (bits_5_9 * 2);] {export *:4 bwd;}
 addr8: addy is bits_0_7s [addy = inst_next + (bits_0_7s * 2);] {export *:4 addy;} 
 addr16: addy is bits_0_15s [addy = inst_next + (bits_0_15s * 2);] {export *:4 addy;}
-addr32: addy is imm32 [addy = (imm32 / 8) & 0xfffff;] {export *:4 addy;}
+addr32: addy is imm32 [addy = imm32 / 8;] {export *:4 addy;}
 
 cc: "" is bits_8_11=0  	{ local tmp:1 = 1; export tmp; }
 cc: "P"  is bits_8_11=1  { local tmp:1 = (!$(N_Flag) & !$(Z_Flag)) != 0; export tmp; }
@@ -182,9 +182,9 @@ macro Update_V_Flag(V)
 # -------------------------------------------------------------------------------------------------------------------------------------#
 # ADDI IL						Add Immediate (32-bytes)															0000 1011 001R DDDD					
 # -------------------------------------------------------------------------------------------------------------------------------------#
-:ADDI link,Rd is bits_5_15=0b00001011001 & Rd; imm32 [link=(imm32 / 8) & 0xfffff;]
+:ADDI imm32,Rd is bits_5_15=0b00001011001 & Rd; imm32
 {
-	Rd = link;
+	Rd = imm32;
 }