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TECH-NOTES FOR
Advanced Demuffin 1.1
Written by
The Stack
Copyright 1983
Corrupt Computing
If you want source code for any of Corrupt Computing's line of
utilities, just contact THE INSPECTOR on THE TWILIGHT PHONE.
================================================================
ZERO PAGE LOCATIONS
$22 WNDTOP These 2 zero page locations, WNDTOP and WNDBTM,
$23 WNDBTM are used so that the character that the
character output routines in the monitor will
output characters only in the window below the
first 3 lines and above the bottom 2 lines.
The top 3 and bottom 2 lines are used for title
lines and status display. These locations
should be restored to normal upon return from
your RWTS if it uses them, although most RWTS's
don't use these reserved monitor locations.
$26 GBASL These 2 zero page locations are used by many
$27 GBASH routines throughout Advanced Demuffin, such as
the PRINT routine and the routines to display
the status codes on the disk map, but they do
not need to be saved before going to your RWTS.
Many RWTS's, including RWTS 3.3, use these
locations in several places.
$36 CSWL CSWL and CSWH should always point to the address
$37 CSWH of the current character output routine.
Advanced Demuffin sets these locations to point
to $FDF0, the standard character output
routine. Note that the outputed characters
will no longer go through DOS as there may be
no DOS in the machine. Advanced Demuffin
changes the contents of these locations to
point to $Cx00 when a number from 1-7 is
pressed during a conversion or after a
conversion is completed, where x is the number
pressed. These locations should be restored to
point to $FDF0 if your RWTS uses them in any
way. Most RWTS's, including RWTS 3.3, don't
use them at all.
$4A TEMP1 Although most RWTS's don't use these locations,
$4B TEMP2 they are used as scratch locations by Advanced
$4C TEMP3 Demuffin and are VERY IMPORTANT! Be sure and
save them if your RWTS even looks at them. The
most important location to save is $4B, which
contains the page number that the current
sector is being loaded into. Note that this is
a duplicate of the X register upon entry into
the user's IOB module at $1400.
PRE-PROGRAM NON-ZERO PAGE LOCATIONS
$200 BUF Page 2, the character input buffer, is used as a
buffer to hold the file name of the RWTS or IOB
module to be loaded. This page may be used by
your RWTS, but your RWTS may not reside in the
area between $200-$21E (unless you don't plan
on loading anything), as this portion of page 2
will be destroyed upon a load.
$3F2 RESET Advanced Demuffin sets this pointer to pnint to
$FF59. This means that whenever the RESET key
is pressed, the Apple will jump into the
monitor. If this is not desired, $12C9 (low
byte) and $12CE (high byte) may be changed to
have the RESET key go wherever you want it to
go including $801 (Advanced Demuffin entry).
$12C9 normally contains a $59 and $12CE
normally contains an $FF.
$3F5 AMPVEC Advanced Demuffin sets up these locations to
$3F8 CTYVEC jump to the Advanced Demuffin entry point
($801) when Applesoft recieved the "&" command
and when the monitor recieved the CTRL-Y
command. This provides a useful way to get
back into Advanced Demuffin after exit.
$400-$7FF Many times Advanced Demuffin displays data and
status marks on the screen by storing this data
directly into this area of memory. This
includes all marks on both the track map and
the disk map as well as numbers on the bottom
screen line, and dashes and other messages on
the 3rd and 23rd lines.
INTER-PROGRAM LOCATIONS
$800 This is the location where Advanced Demuffin is
designed to run at. This location contains an
$EA (NOP) as the byte at $800 is often replaced
by a $00. This is NOT the entry point to
Advanced Demuffin ($801 is the entry) although
if there is an $EA here it won't make any
difference if you use this as the entry.
$801 START0 This is the entry point to Advanced Demuffin 1.1
where there are two instructions, SEI and CLD,
before the actual START of Advanced Demuffin.
$803 START This is the actual start of the program which
sets CSWL and CSWH to point to the monitor
routine COUT1, sets the RESET, AMPVEC, and
CTYVEC as mentioned above (see appropriate
label), sets the full screen as a window except
for the top 3 and the bottom 2 lines, clears
the screen, puts the title at the top, the
status line at bottom, and starts off the
program by displaying the menu.
$F1E IOB This is the IOB that Advanced Demuffin uses when
it uses RWTS. The built-in IOB module (IOB33)
which is described below, as well as the
default user IOB module (at $1400) also use
this IOB. The default contents of this IOB are
described in detail below:
$F1E:01 60 IOB DFB $01,$60
$F20:01 DRIVE DFB $01
$F21:00 VOLUME DFB $00
$F22:00 TRACK DFB $00
$F23:00 SECTOR DFB $00
$F24:2F 0F DW DCT
$F26:00 DPAGL DFB $00
$F27:80 DPAG DFB $80
$F28:00 00 DFB $00,$00
$F2A:01 CODE DFB $01
$F2B:00 ERROR DFB $00
$F2C:00 60 01 DFB $00,$60,$01
$F2F:00 01 DCT DFB $00,$01
$F31:EF D8 DFB $EF,D8
Note that the slot number used by Advanced Demuffin could easily
be changed bu changing $F1F to the $x0 where x is the slot
number of the desired drive.
$F33 IOB33 This is the built-in IOB module used to write to
3.3 formatted disks. A disassembled listing of
it is included below:
$F33- IOB33 STY SECTOR ;Store sector
$F36- STX DPAG ;and page number
$F39- LSR A ;Convert phase # to track #
$F3A- STA TRACK ;and store it
$F3D- LDA DRV ;Check # of drives
$F40- STA DRIVE ;and store it as drive to write to
$F43- THERE LDA #2 ;Set command code to write
$F45- STA CODE ;and store it
$F48- JSR GORWTS ;and go to 3.3 RWTS to write it
$F4B- LDA #1 ;Restore read
$F4D- STA CODE ;command code
$F50- LDA ERROR ;Check for an error
$F53- BCC RTS4 ;Exit if none
$F55- CMP #$10 ;Write protect error?
$F57- SEC ;Keep carry set
$F58- BNE RTS4 ;Not write protect, exit w/carry set
$F5A- LDY #$27 ;Display write protected
$F5C- MOV4 LDA WPER1,Y ;error message
$F5F- STA SCLN1,Y ;and ask whether
$F62- LDA WPER2,Y ;to continue or
$F65- STA SCLN2,Y ;start over
$F68- DEY
$F69- BPL MOV4
$F6B- JSR PRINT ;Print 3 beeps
$F6E- DFB $07,$07,$87
$F71- KEY10 JSR KEYIN ;Read a key - go back to menu if esc
$F74- CMP #$C3 ;Continue?
$F76- BEQ CONTIN ;Yes, branch
$F78- CMP #$D3 ;Start over?
$F7A- BNE KEY10 ;No
$F7C- PLA ;Yes
$F7D- PLA ;Pull return address off stack
$F7E- JSR REPLNS ;Replace top 2 lines w/ title lines
$F81- JMP GOTVAL ;Starts over
$F84- CONTIN JSR REPLNS
$F87- BMI THERE ;Always taken
$13FA-$13FB These 2 bytes are unused
$13FC-$13FF These 4 bytes are reserved for the address and
the length of the IOB module when it is being
loaded. Advanced Demuffin loads the first
sector from the track/sector list of the IOB
module at $13FC. Since the first 4 bytes of
this sector contain the address and the length
of the file, those bytes reside in these
locations. Therefore, the actual IOB module
will start at $1400 (just below).
$1400 IOBM This is the user IOB module. The LOAD NEW IOB
MODULE will load a file into this area (see
above). A disassembled listing of the default
user IOB module is included in the main manual.
$1419-$14FB These bytes between the user IOB module and RWTS
3.3 are left free for an IOB module longer than
the default one. This allows an IOB module to
take up as much as $FC bytes total.
$14FC-$14FF These 4 bytes are unused.
$1500-$1CDB RWTS 3.3 resides in this area of memory. It is
just standard RWTS that has been relocated to
run at this address. Advanced Demuffin uses
the entry at $1A00.
Below are some other locations used as scratch by Advanced
Demuffin. These may be looked at by your IOB module in
determining various options about how it is to read sectors
from the source disk if desired.
$1CE0 SCVER This location contains either a $0C or a $0F
for 13 and 16 sector modes, respectively.
$1CE1 STPHS This location contains phase number to start
reading data from the disk with. It defaults
to $00. (Since it is a phase #, a $01 would
mean track .5, etc.)
$1CE2 ENPHS ENPHS is the same as STPHS except that it
contains the last phase to read data from.
$1CE3 STSEC STSEC contains the first sector within the phase
specified by STPHS that data should be read
from.
$1CE4 ENSEC ENSEC contains the last sector within the phase
specified by ENPHS that data should be read
from.
$1CE5 CRPHS This location contains the current phase that
data is being read from.
$1CE6 CRSEC This location contains the current sector that
data is being read from.
$1CE7 BGSEC BGSEC contains the sector number within the
phase specified by BGPHS (below) that data has
started being read from this pass. i.e. If you
are converting an entire 16 sector disk with
the default options and the default buffer size
($70 pages), during the first pass BGPHS and
BGSEC will both contain a $00 (phase 00, sector
00 was the start phase, sector in this pass).
During the second pass, BGPHS and BGSEC will
contain $0E and $00, respectively. (The second
pass started with track 07, sector 00 and track
07 is phase $0E).
$1CE8 BGPHS See above.
$1CE9 BYPHS This byte contains the increment in phases.
i.e. The default increment, 1.0, would be $02.
$1CEA NRETRY This byte contains the maximum number of retries
(normally $01).
$1CEB RETRY This byte is used as a counter counting down
from the maximum number of retries to $00. On
the first attempt to read a sector, RETRY will
equal NRETRY. If the carry is set upon return
from the user's IOB module, RETRY will be
decreased. If it is less than zero, a read
error will result. If not, a read will be re-
attempted. This process will continue until
the sector either reads correctly or until
RETRY is less than zero.
$1CEC DRV This location contains either a one or a two
respective to the number of drives being used.
The built-in IOB module uses this location to
determine which drive to write data to.
$1CED-$1CEF These 3 bytes are unused
$1CF0 BUFST BUFST contains the page number of the start of
the buffer. This buffer is used to store data
read off the source disk. By changing this
location and/or BUFEN (below) you can easily
change the buffer size and the location of
Advanced Demuffin's buffer. This location
normally contains a $20 meaning that the buffer
normally starts at $2000.
$1CF1 BUFEN BUFEN contains the page number of the first page
not to be included in Advanced Demuffin's
buffer (see above). i.e. If this location
contained a $90 (the default value) and BUFST
(see above) contained a $20 (the default again)
the buffer would reside from $2000 to $8FFF
(which it normally does). However, this
byte may be changed from a $90 to another
value, such as a $B8, making the buffer much
larger. In this example, your buffer would be
$9800 bytes long! This will, of course, erase
DOS when you attempt to convert the disk; but
no problem - Advanced Demuffin does not require
DOS anyway. (Not even for loading RWTS and IOB
modules!) Another use for changing this byte
the one before it is to move the buffer to a
different place. i.e. If you had a hi-res
screen on hi-res page 1 ($2000-$3FFF) that you
wanted to keep in memory, you could simply
change BUFST ($1CF0) to $40, forcing the buffer
to start at $4000 instead of $2000 - saving
your screen.
$1F00 DIRSEC This page is used as a scratch page when loading
sectors from the disk. i.e. When loading a
RWTS or an IOB module, the directory sector
containing the name of the file to load will be
read into this page. The track and sector of
the track/sector list will be found and the
track/sector list will then be loaded here.
$BD00 USRRWTS This is address JuMPed to by the default user
RWTS. You should either have an RWTS here or
the IOB module should be changed to point to a
different location. Note the $BD00 does not
necessarily have to be the start of the RWTS
when using the default user IOB module, it must
be the ENTRY POINT of the RWTS. In fact, most
RWTS's have a STARTING ADDRESS of $B800 but an
ENTRY POINT at $BD00. Keep this in mind when
you load an RWTS module from disk.
$C000 KEYBD These are the only hardware locations used by
$C010 KEYCLR Advanced Demuffin other than during the screen
dump where $Cx00 is JSRed to (where x is the
slot number).
The following monitor routines are used by Advanced Demuffin:
$F847 GBASCALC
$FB2F INIT
$FC58 HOME
$FD8E CROUT
$FDED COUT
$FDF0 COUT1
$FF59 MONITOR