Commodore 1541 Drive ROM addresses
; Commodore 1541 / OC-118 Disk Drive ROM Map
; V1.0 1 Sep 1994
; Note: This Memory map is collected from the 1541 disassembly
; which was made by Peter Weighill. I cannot guarantee accuracy
; of all details.
;
; Data types in headers (for reassembler):
;
; DATA Misc data
; TEXT String terminated with 00
; WORD Vectors in LO/HI byte pairs
; CHIP I/O Area
; EMPTY ROM containing AA's or FF's
;
c000 Unused EMPTY
;c100 File Manager Routines
c100 Turn LED on
c118 Turn LED on
c123 Clear error flags
c12c Prepare for LED flash after error
c146 Interpret command from computer
c194 Prepare error msg after executing command
c1bd Erase input buffer
c1c8 Output error msg (track and sector 0)
c1d1 Check input line
c1e5 Check input line
c1ee Check input line
c268 Search character in input buffer
c2b3 Check line length ptr in command
c2dc Clear flags for command input
c312 Preserve drive number
c33c Search for drive number
c368 Get drive number
c38f Reverse drive number
c398 ?
c3bd Check drive number
c3ca Verify drive number
c440 Flags for drive check DATA
c44f Search for file in directory
c63d Test and initalise drive
c66e Name of file in directory buffer
c688 ?
c6a6 Search for end of name in command
c6ce ?
c6de ?
c7ac Clear Directory Output Buffer
c7b7 Create header with disk nmae
c806 Print 'blocks free.'
c817 'Blocks free.' DATA
c823 Perform [S] - Scratch command
c87d Erase file
c8b6 Erase dir entry
c8c1 Perform [D] - Backup command (Unused)
c8c6 Format disk
c8f0 Perform [C] - Copy command
ca88 Perform [R] - Rename command
cacc Check if file present
caf8 Perform [M] - Memory command
cb20 M-R memory read
cb50 M-W momory write
cb5c Perform [U] - User command
cb84 Open direct access channel, number
cc1b Perform [B] - Block/Buffer command
cc5d Block commands "AFRWEP" DATA
cc63 Block command vectors WORD
cc6f Get parameters form block commands
ccf2 Decimal values 1, 10, 100 DATA
ccf5 B-F block free
ccfe ?
cd03 B-A block allocate
cd36 ?
cd3c Get byte from buffer
cd42 Read block from disk
cd56 B-R block read
cd5f U1, Block read without changing buffer pointer
cd73 B-W block write
cd97 U2, Block read without changing buffer pointer
cda3 B-E block execute
cdbd B-P block pointer
cdd2 Open channel
cdf2 Check buffer number and open channel
ce0e Set pointer for REL file
cd2c ?
cd6e Divide by 254
ce71 Divide by 120
cdd9 Erase work storage
dee2 Left shift 3-byte register twice
cee5 Left shift 3-byte register once
ceed ?
cefa ?
cf09 ?
cf1e ?
cf8c Change buffer
cf9b Write data in buffer
cff1 Write data byte in buffer
d005 Perform [I] - Initalise command
d00e ?
d042 Load BAM
d075 Calculate blocks free
d09b ?
d0c3 Read block
d0c7 Write block
d0eb Open channel for reading
d107 Open channel for writing
d125 Check for file type REL
d12f Get buffer and channel numbers
d137 Get a byte from buffer
d156 Get byte and read next block
d19d Write byte in buffer and block
d1c6 Increment buffer pointer
d1d3 Get drive number
d1df Find write channel and buffer
d1e2 Find read channel and buffer
d227 Close channel
d25a Free buffer
d28e Find buffer
d307 Close all channels
d313 Close all channels of other drives
d339 ?
d37f Find channel and allocate
d39b Get byte for output
d44d Read next block
d460 Read block
d464 Write block
d475 Allocate buffer and read block
d486 Allocate new block
d48d Write dir block
d4c8 Set buffer pointer
d4da Close internal channel
d4e8 Set buffer pointer
d4f6 Get byte from buffer
d506 Check track and sector numbers
d552 Get track and sector numbers for current job
d55f Check for vaild track and sector numbers
d572 DOS mismatch error
d586 Read block
d58a Write block
d599 Verify execution
d5c6 Additional attempts for read errors
d676 Move head by half a track
d693 Move head one track in or out
d6a6 Attempt command execution multiple times
d6d0 Transmit param to disk controller
d6e4 Enter file in dir
d7b4 OPEN command, secondary addr not 15
d8f5 Open a file with overwriting
d9a0 Open file for reading
d9e3 Open file for writing
da09 Check file type and control mode
da2a Preparation for append
da55 Open directory
dac0 Close routine
db02 Close file
db62 Write last block
dba5 Directory entry
dc46 Read block, allocate buffer
dcb6 Reset pointer
dcda Construct a new block
dd8d Write byte in side-sector block
dd95 Manipulate flags
ddab Verify command code for writing
ddb7 ?
ddf1 Write a block of a REL file
ddfd Write bytes for following track
de0c Get following track and sector numbers
de19 Following track for last block
de2b buffer pointer to zero
de3b Get track and sector
de50 Write (?)
de57 R
de5e W
de65 R
de6c W
de73 R
de95 Get following track and sector from buffer
dea5 Copy buffer contents
dec1 Erase buffer Y
ded2 Get side-sector number
dedc Set buffer pointer to side-sector
dee9 Buffer pointer for side-sector
def8 Get side sector and buffer pointer
df1b Read side-sector
df21 Write side-sector
df45 Set buffer pointer in side-sector
df4c Calculate number of blocks in a REL file
df66 Verify side-sector in buffer
df93 Get buffer number
dfd0 Get next record iin REL file
e03c Write block and read next block
e07c Write a byte in a record
e0ab Write byte in REL file
e0f3 Fill record with 0s
e105 Write buffer number in table
e120 Get byte from REL file
e1cb Get last side-sector
e207 Perform [P] - Position command
e2e2 Divide data blocks into records
e304 Set pointer to next record
e31c Expand side-sector
e44e Write side-sector and allocate new
e4fc Table of error messages DATA
; Format: error numbers
; description
; (with start and end letters +$80) If value AND $7F less
; than $10 then look up text in pointer table.
;
;e4fc Ok
;e500 Read error
;e50b File too large
;e517 Record not present
;e522 Overflow in record
;e52f Write error
;e533 Write protect on
;d540 Disk id mismatch
;e546 Syntax error
;e552 Write file open
;e556 File exists
;e55f File type mismatch
;e567 No block
;e570 Illegal track or sector
;e589 File not open
;e58d File not found
;e592 Files scratched
;e59f No channel
;e5aa Dir error
;e5af Disk full
;e5b6 Cbm dos v2.6 1541
;e5c8 Drive not ready
e5d5 Indexed words DATA
; Format: index number
; description
e60a Prepare error number and message
e645 Print error message into error buffer
e680 TALK
e688 LISTEN
e69b Convert BIN to 2-Ascii (error message buffer)
e6ab Convert BCD to 2-Ascii (error message buffer)
e6bc Write OK in buffer
e6c1 Print error on track 00,00 to error buffer
e6c7 Print error on current track to error buffer
e706 Write error message string to buffer
e754 Get character and in buffer
e767 Get a char of the error message
e775 Increment pointer
e77f ?
e780 Check for auto start removed
e7a3 Perform [&] - USR file execute command
e84b Generate checksum
e853 IRQ routine for serial bus
e85b Service the serial bus
e909 Send data
e99c DATA OUT lo
e9a5 DATA OUT hi
e9ae CLOCK OUT hi
e9b7 CLOCK OUT lo
e9c0 Read IEEE port
e9c9 Get data byte from bus
e9f2 Accept byte with EOI
ea2e Accept data from serial bus
ea59 Test for ATN
ea6e Flash LED for hardware defects, self-test
eaa0 Power-up RESET routine
ebff Wait loop
ec9e Load dir
ed23 ?
ed59 Transmit dir line
ed67 Get byte from buffer
ed84 Perform [V] - Validate command
edb3 ?
ede5 Allocate file blocks in BAM
ee0d Perform [N] - New (Format) command
eeb7 Create BAM
eef4 Write BAM if needed
ef3a Set buffer pointer for BAM
ef4d Get number of free blocks for dir
ef5c Mark block as free
ef88 Set flag for BAM changed
ef90 Mark block as allocated
efcf Erase bit for sector in BAM entry
efe9 Powers of 2 DATA
eff1 Write BAM after change
f005 Erase BAM buffer
f011 ?
f05b ?
f0df ?
f10f Get buffer number for BAM
f119 Buffer number for BAM
f11e Find and allocate free block
f1a9 Find free sector and allocate
f1fa Find free sectors in current track
f220 Verify number of free blocks in BAM
f24b Establish number of sectors per track
f258 Dummy subroutine
;
;f259 Disk Controller Routines
;
f259 Initialise disk controller
f2b0 IRQ routine for disk controller
f2f9 Head transport
f36e Execute program in buffer
f37c Bump, find track 1 (head at stop)
f393 Initialise pointer in buffer
f3b1 Read block header, verify ID
f410 Preserve block header
f418 Work Return value 01 (OK) into queue
f41b Work Return value 0B (READ ERROR) into queue
f41e Work Return value 09 (READ ERROR) into queue
f423 Job optimisation
f4ca Test command code further
f4d1 Read sector
f50a Find start of data block
f510 Read block header
f556 Wait for SYNC
f56e Test command code further
f575 Write data block to disk
f5e9 Calculate parity for data buffer
f5f2 Convert buffer of GCR data into binary
f691 Test command code further
f698 Compare written data with data on disk
f6ca Command code for find sector
f6d0 Convert 4 binary bytes to 5 GCR bytes
f77f GCR (5-bit) nybble table DATA
f78f Convert 260 bytes to 325 bytes group code
f7e6 Convert 5 GCR bytes to 4 binary bytes
f8a0 Conversion table GCR to binary - high nybble
; $FF means invalid
f8c0 Conversion table GCR to binary - low nybble
; $FF means invalid
f8e0 Decode 69 GCR bytes
f934 Convert block header to GCR code
f969 Error entry disk controller
f97e Turn drive motor on
f98f Turn drive motor off
f99c Job loop disk controller
f9cb ?
f9d9 ?
fa05 Move head to next track
fa1c Calculate number of head steps
fa3b Move stepper motor short distance
fa4e Load head
fa63 ?
fa7b Prepare fast head movement
fa97 Fast head movement
faa5 Prepare slow head movement
fac7 Formatting
fda3 Write SYNC 10240 times, erase track
fdc3 Read/write ($621/$622) times
fdd3 Attempt counter for formatting
fde5 ?
fdf5 Copy data from overflow buffer
fe00 Switch to reading
fe0e Write $55 10240 times
fe30 Convert header in buffer 0 to GCR code
fe67 Interrupt routine
fe85 Constands for disk format
fe85 Directory track DATA
fe86 Start of bam DATA
fe87 Length of bam per track DATA
fe88 End of bam DATA
fe89 Table of command words DATA
; "VIDMBUP&CRSN"
; Validate, Initialise, D(Backup unused),
; Memory, Block, User,
; Position, ∧USR execute, Copy,
; Rename, Scratch, New (Format).
fe95 Low byte of command addresses DATA
fea1 High byte of command addresses DATA
fead Bytes for syntax check DATA
feb2 File control methods "RWAM" DATA
feb6 File types "DSPUL" DATA
febb Names of file types DATA
febb 1st letter "DSPUR" DATA
fec0 2nd letter "EERSE" DATA
fec5 3rd letter "LQGRL" DATA
feca Error LED bit value DATA
fecd Masks for bit command DATA
fed1 Number of sectors per track DATA
fed5 Constands for disk format DATA
fed5 'A' marker for 1541 format DATA
fed6 4 track ranges DATA
fed7 Number of tracks DATA
fed8 Tracks on which sector numbers change DATA
fedb Control bytes for head postion DATA
fee0 Buffer address high bytes DATA
fee6 ROM checksum DATA
fee7 From UI command $EB22, to reset
; Without RAM/ROM test
feea Patch for diagnostic routine from $EA7A
fef3 Delay loop for serial bus in 1541 mode, from $E97D
fefb Patch for data output to serial bus, from $E980
ff01 U9 vector, switch 1540/1541
ff10 Patch for reset routine, from $EAA4
ff20 Patch for listen to serial bus, from $E9DC
ff2f Unused EMPTY
ffe6 Format [C8C6]
ffe8 Turn motor off [F98F]
ffea USER vectors
ffea UA, U1 [CD5F]
ffec UB, U2 [CD97]
ffee UC, U3 [0500]
fff0 UD, U4 [0503]
fff2 UE, U5 [0506]
fff4 UF, U6 [0509]
fff6 UG, U7 [050C]
fff8 UH, U8 [050F]
fffa UI, U9 [FF01]
fffc Hardware vectors
fffc RESET [EAA0]
fffe IRQ [FE67]
Converted to a human readable format by the IIRG