Phase 1: enrich 07_dos and 10_devices (highest FPGA priority)
07_dos:
- file_io.md: 108→240+ lines — buffered I/O (FRead/FWrite/SetVBuf),
access mode comparison, FileHandle struct with offsets, standard
handles, Printf %ld warning, FileInfoBlock, practical patterns
(copy file, get size, load to RAM), error code table
- filesystem.md: 91→270+ lines — full disk geometry (ADF/HDF),
all 8 DOS\x filesystem IDs, root block byte-level layout, file
header layout with reverse-order pointer quirk, OFS vs FFS data
blocks with efficiency numbers, bitmap blocks, extension blocks,
checksum algorithm, Python ADF reader
- locks_examine.md: 113→270+ lines — lock semantics diagram, FileLock
struct with handler discovery, ExAll bulk scan, practical patterns
(atomic write, path resolution, volume info), 4 antipatterns
(leaked locks, exclusive too long, unchecked IoErr, DupLock),
pattern matching
10_devices:
- audio.md: 73→240+ lines — hardware architecture diagram, channel
registers with offsets, period/frequency table, priority allocation,
double-buffering, audio interrupts, AM/PM modulation, direct HW
- timer.md: 80→230+ lines — CIA timer hardware, all 5 units with
decision flowchart, non-blocking delays, signal-based waiting,
time arithmetic, ReadEClock, periodic game loop pattern, pitfalls
- trackdisk.md: 82→210+ lines — MFM encoding, track format, disk
geometry, read/write/motor, change notification, track caching,
direct hardware access, FPGA timing implications
- keyboard.md: 58→220+ lines — CIA-A serial handshake protocol with
sequence diagram, bit rotation quirk, complete key code map,
key matrix bitmap, reset sequence, FPGA notes
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