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https://git.k-space.ee/arti/vt1200.git
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SDD
9902722165
Root cause of the missing THRA write (HOST PORT test): the level-1 host-port
test's transmit is ISR-driven, and the DUART interrupt was never wired to the
CPU. The firmware installs RAM trampolines in the fixed vector table (INT1
vector 0xffffffc0 -> stub at bit 0x0f60 = JA 0x3FA92F40, which calls the DUART
ISR L3FA78D90 with (2, 0x270860, 0x6400000)). Counters: INTENB reaches 0x0006
(INT1|INT2) at the test, so interrupts are enabled.
vt1200.cpp: wire m_duart1/m_duart2 irq_cb() to CPU external interrupt 1/2
(duart1_irq_w/duart2_irq_w), gated on VT1200_DUART. Result: THRA writes go
from 0 to 20 per run; the test's SRA-overrun and RHRA-pattern checks now pass.
MAME tree (mc68681.cpp/.h), two datasheet-backed corrections with revert notes:
1. TxRDY was asserted mid-character ("not until the end of start bit time");
the datasheet asserts it at the THR->TSR transfer. Corrected.
2. The overrun error was latched when the overrunning character *completed*
(rx_fifo_push); the datasheet latches it "upon receipt of the start bit of
the new (overrunning) character". Corrected via duart_channel::rx_w().
This clears every check in the RXCHECK sub-test (flags 1 -> 0).
Acceptance is NOT met: cap.lua still prints 'LEVEL1/2 ERROR -> HOST PORT - 15'.
The next failure is the preceding L3FA71BC0 (DUART baud/timer) sub-test
returning 6; its flag-set sites were breakpointed and never fired. Regression
holds (no VT1200_* env -> PC=3FDCE400 samples=199). Details, numbers and the
datasheet audit: harness/mame/DUART_REPORT.md sections FINAL FINDINGS / UPDATE.
51 lines
1.5 KiB
Lua
51 lines
1.5 KiB
Lua
-- hp_trace.lua -- dynamic trace of the level-1 HOST PORT test.
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--
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-- Polls (per frame, via the address map so device side effects apply):
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-- INTENB/INTPEND (CPU I/O regs)
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-- DUART1 ISR (window 0x06400000 + reg 5 -> program space 0x06400050)
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-- DUART1 SRA (reg 1 -> 0x06400010)
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-- DUART1 CRA read? no (write-only-ish); MR1A read ok (reg 0 -> 0x06400000)
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-- DO NOT read reg 3 (RHRA) -- it pops the FIFO.
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--
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-- Also breaks at key PCs and logs registers.
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--
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-- HP_FRAMES=900 <mame> vt1200 ... -autoboot_script harness/mame/hp_trace.lua
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local machine = manager.machine
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local cpu = machine.devices[':maincpu']
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local dbg = machine.debugger
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local prog = cpu.spaces['program']
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if not dbg then print("ERROR: no debugger"); machine:exit(); return end
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local rd = function(a) return prog:read_u16(a) end
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local maxframes = tonumber(os.getenv("HP_FRAMES") or "900")
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local n = 0
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-- Frame polling: report changes and every 25 frames a compact snapshot.
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local last = {}
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local keys = {
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INTENB = 0xc0000110,
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INTPEND = 0xc0000120,
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D1_ISR = 0x06400050, -- reg 5
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D1_SRA = 0x06400010, -- reg 1
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D1_MR1 = 0x06400000, -- reg 0
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}
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emu.register_frame_done(function()
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n = n + 1
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for name, addr in pairs(keys) do
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local v = rd(addr)
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if last[name] ~= v then
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print(string.format("f%4d %s CHANGED -> %04X", n, name, v))
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last[name] = v
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end
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end
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if n >= maxframes then
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print("done (" .. n .. " frames)")
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machine:exit()
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end
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end, "vt1200-hp")
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dbg.visible_cpu = cpu
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dbg.execution_state = 'run'
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