# Revision history

"Those days, the Third Age of Middle-earth,
are now long past, and the shape of all lands
has been changed."

This emulator started as a player routine for C64 music on the Amiga. Versions V1.x were written in 68K assembly language, versions V2.x in a mix of 68K assembly and C. V3.x/V4.x are portable versions written in C++.

### V1.x/V2.x

- Amiga 68K versions

### V3.0

- First release of BeOS/Unix version, features processor-level 1541 emulation and built-in SID emulation

### V3.0a

- Implemented SID test bits
- Combined SID waveforms respect pulse width
- Corrected idle state graphics display
- Processor-level 1541 emulation respects .d64 error info
- CPU emulation optimized (6510 and 6502 split)
- VIC emulation optimized (raster counter in local variable in EmulateLine())
- BeOS: Now exiting the audio subscriber with ExitStream(TRUE)
- Unix: Fixed missing thread_func() declaration
- Unix: getcwd(AppDirPath) was missing in main_x.i
- Unix: Speed limiter works

### V3.0b

- Implemented REU emulation
- Formatting disks with ID possible under processor-level 1541 emulation
- Corrected and optimized SID waveform/envelope calculation (signed arithmetic)
- Corrected idle state display again (ECM text)
- 1541 D64 mode ignores drive numbers when opening the directory
- Processor-level 1541 emulation deactivates when idle
- BeOS: Sound output quality is now 16 bits
- Unix: Quits more cleanly, reactivates key repeat
- Unix: Fixed alignment problem with text_chunky_buf in VIC.h

### V3.0c

- 1541 DIR mode can load directory with "$0"
- Rearranged the CPU code (more macros, less inline functions)
- SID envelope generators rewritten, envelopes are now recalculated for every sample
- SID calc_buffer function now takes pointer to WORD buffer
- Unix: Sound for Linux
- Unix: Prefs window implemented (needs Tcl/Tk)
- Unix: Corrected x64 disk image detection on little-endian systems
- Unix: SVGAlib support works again, accesses frame buffer directly if possible
- Unix: Added support for SHM under X11

### V3.0d

- SID filter emulation implemented
- SID master volume setting works again
- Flags are recalculated in MOS6526::SetState()
- Changed CBOOL->bool in some places
- Fixed bug with char_in in MOS6510::new_config()
- BeOS: Emulation thread priority lowered
- Unix: Some changes for DEC Alpha
- Unix: Joystick support for Linux

### V3.0e

- Removed the CBOOL data type
- Unix: Sound for HP-UX
- Unix: Keyboard layout matches the picture in the docs more closely
- Unix: Diagonal directions of keypad joystick emulation work
- Unix: +/- on numerical keypad modifies SkipFrames
- Unix: F9 invokes SAM
- Unix: Drive LEDs and speedometer implemented
- Unix: Some changes to the GUI
- Unix: Random number generator is initialized
- Unix: Name of prefs file can be given as an argument
- Unix: Calls XFlush() and XSync() in C64Display::Update()

### V3.0f

- Improved DIR/D64 drive reset, resetting the C64 resets the drives
- Implemented 'G' command for DIR/D64 drives
- Corrected translation of 0xc1..0xda characters in conv_from_64()
- BeOS: Implemented smart "Insert next disk" menu item
- Unix: Improved the speedometer/LED bar
- Unix: Self-calibrating joystick routines
- Unix: No need to enter path of 'wish' in TkGui.tcl

### V3.0g

- New T64/LYNX mode for 1541 emulation
- 1541fs.cpp/match() used to treat the pattern "foo" as "foo*"
- 1541 DIR mode uses tmpfile() for opening temporary directory files
- 1541 D64 mode allows wildcards for selective directory reading
- Increased compatibility of processor-level 1541 emulation in various places (C64<->1541 communication, VIA registers, memory map, disk change flag)
- Inlined MOS6526::EmulateLine() and some small public functions of MOS6502_1541
- New prefs option to enable/disable SID filter emulation
- Joystick calibration is reset when joystick options change
- BeOS: Self-calibrating joystick routines

### V3.0h

- Implemented SID notch filter, better resonance frequency calculation
- Fixed bug with SID filter option
- CIA timer B one-shot mode stops timer when counting undeflows of timer A
- Implemented lightpen trigger
- BeOS: Fixed for BeOS DR8, improved the GUI a bit
- Unix: Some fixes to the TkGui (T64, SIDFilters, removed speed display)
- Unix: Main window no longer resizable
- Unix: SVGALib support works again

### V3.1

- BeOS: Joysticks work again

### V3.1a

- Frodo SC ported
- Processor-level 1541 emulation supports reading GCR data, removed the faked job loop
- Corrected ISB, RRA, SBX and SHA instructions
- The last line of Y expanded sprites wasn't drawn
- Light pen registers work
- Small fixes to 1541d64/1541t64
- CIA 2 PRA write: IEC lines respect DDRA
- Better triangle waveform (12 bits)
- SID emulation can play sampled sounds
- New "Ignore SID Volume" prefs item for better sample playing
- '*' on numerical keypad toggles speed limiter
- BeOS: '/' on numerical keypad toggles processor-level 1541 emulation
- BeOS: Safer quitting
- BeOS: Option to use GameKit (screen)
- BeOS: Replaced srand(system_time()) with srand(real_time_clock())
- Unix: Sun makefile

### V3.1b

- Corrected SID sustain behaviour
- Reading from write-only SID registers returns the last byte written to the SID
- No more distortions when playing samples
- Removed the "Ignore SID Volume" prefs item again
- Combined SID waveforms now sampled from a 6581R4
- Improved 1541 VIA timer operation
- Fixed bug in 1541 head movement
- Raster IRQs can be triggered by writing to $d011/$d012
- Some changes for the MacOS port
- Included autoconf stuff from Bernd
- Frodo SC: Fixed some CIA timer bugs

### V3.1c

- Ported to AmigaOS
- Fixed bug in IEC::Reset()
- Fixed bug when writing to SID registers >24
- The SID noise waveform should now sound the same on all platforms
- Removed all calls to tolower() in SAM.cpp because of possible side-effects if tolower() is a macro
- Drive LEDs are only updated once per frame
- .d64/.t64 files are opened with read permissions only
- Fixed bug with read_char buffering in 1541fs.cpp/1541t64.cpp
- Frodo SC: Fixed memory trashing bug in MOS6569::draw_background()
- Unix: Drive LEDs blink on error
- Unix: Added more patches from Bernd

### V4.0

- The C64 ROM files are now included
- Unix: Added SVGAlib keyboard patches from Bernd

### V4.0a

- Corrected BRK, ANE, ARR, SBX and DCP instructions
- Frodo SC: Improved the CIA timers
- Frodo SC: MOS6526::EmulateCycle() split into MOS6526::EmulateCycle() and MOS6526::CheckIRQs()
- Frodo SC: Corrected interrupt behaviour of branch instructions
- BeOS: Sound calculation is now done in stereo

### V4.1

- Integrated Win32 and RiscOS ports
- Snapshot support
- Added page-crossing and "borrowed" cycles in line-based CPU emulation (Frodo PC)
- Added precise CIA cycles for line-based emulation (Frodo PC)
- Optional fixed-point arithmetic and precomputed filters in SID.cpp
- Optional dynamic alignment checks in VIC.cpp
- Changed typedefs and constants (BYTE, WORD etc.)
- Unix: Better configure script
- Unix: Sound support for Solaris 2.x
- Unix: Joystick can be toggled between port 1/2 with the NumLock key
- Unix: US keyboard layouts supported
- BeOS: Fixed for BeOS AA:DR9
- BeOS: Can now switch between window/screen mode while the emulation is running, speeded up full screen mode
- BeOS: Prefs saved in /system/settings/Frodo_settings by default