This document is based off what little I could glean from the 64DD BIOS,
existing code and annotations in expansion-pak enabled cartridges,
and some basic eye-and-ear sort of work. With any luck, it may prove useful.
64DD file system is internally called LEO. All commands start with a common 8 byte header.
LBA ROM mirrors LBA RAM, and each is divided into 7 segments. LBA appears to range from 0 to 0x10C4.
command header format:
CM00CN00 STCD0000 message follows
CM command #
CN control bitflags
ST status
CD condition codes
control bitflags:
80 enable post queue
01 start command, set when determining writable filesize and when translating to LBA
02 standby mode
drive state:
01 no disk
02 head retracted
04 spindle stopped
status:
00 no error
02 check condition
08 busy
error conditions:
00 no error
01 drive not ready
02 diagnostic failure
03 command error
04 data error
05 clock failure
0B disk unreadable
15 seek error
16 write error
17 read error
18 lookup error
19 track or spindle failure
1F invalid opcode
20 LBA out-of-range
21 write-protection encountered
22 command terminated
23 queue full
24 bad timer value
29 device not found
2A no disk present
2B drive reset
2D disk not booted
2E disk not swapped
2F disk swapped
30 IPL: clock not set correctly
31 disk ejected illegally
32 IPL: reset - diagnostic failure
33 IPL: reset - ejected illegally
These are names found internally in debug messages, so they may have come from source
LEOCmdClearQue 01 clear queue command
0x0 8 header
LEOCmdInquiry 02 version inquiry command
0x0 8 header
0x8 1 device type
0x9 1 version
0xA 1 device number
0xB 1 BIOS version
0xC 4 RESERVED
LEOCmdTestUnitReady 03 test if unit ready command
0x0 8 header
0x8 1 test
0x9 3 RESERVED
LEOCmdRezero 04 reinitialize command
0x0 8 header
LEOCmdRead 05 read command
0x0 8 header
0x8 4 LBA
0xC 4 transfer blocks
0x10 4 p->buffer
0x14 4 # raw bytes
LEOCmdWrite 06 write command
0x0 8 header
0x8 4 LBA
0xC 4 transfer blocks
0x10 4 p->buffer
0x14 4 # raw bytes
LEOCmdSeek 07 seek command
0x0 8 header
0x8 4 LBA
LEOCmdStartStop 08 start/stop drive command
0x0 8 header
LEOCmdReadCapacity 09 read disk capacity
0x0 8 header
0x8 4 LBA start
0xC 4 LBA end
0x10 4 capacity in bytes
LEOCmdTranslate 0A translate LBA command
0x0 8 header
0x8 4 LBA start
0xC 4 in
0x10 4 out
LEOCmdModeSelect 0B mode select command
0x0 8 header
0x8 1 page
0x9 1 RESERVED
0xA 1 standby time
0xB 1 sleep time
0xC 1 LED on time
0xD 1 LED off time
0xE 2 RESERVED
LEOCmdReadDiskId 0C pull disk ID command
0x0 8 header
0x8 4 p->target
LEOCmdReadTimer 0D read timer command
0x0 8 header
0x8 2 RESERVED
0xA 1 year
0xB 1 month
0xC 1 day
0xD 1 hour
0xE 1 minute
0xF 1 second
LEOCmdWriteTimer 0E write timer command
0x0 8 header
0x8 2 RESERVED
0xA 1 year
0xB 1 month
0xC 1 day
0xD 1 hour
0xE 1 minute
0xF 1 second
+_+
Miscellaneous:
Disk version info:
0x0 4 game ID, typically D--R or E--R, meaning 'disk' or 'expansion', 2 letter name, region
0x4 1 version
0x5 1 disk number
0x6 2 usage
0x8 8 serial line number
0x10 1 RESERVED
0x11 2 year
0x13 1 month
0x14 1 day
0x15 1 hour
0x16 1 minute
0x17 1 second
0x18 2 company code
0x1A 6 RESERVED
drive state:
0 drive active
1 drive standby
2 drive sleep
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