What is it?Frodo is an emulator for the Commodore 64 computer. It allows original software from the Commodore 64 to be loaded from disk and played on your Macintosh.What is required to run it?MacFrodo will run on any Macintosh, 68K or PowerPC, with a 256 colour screen. For best results, a screen of size 800x600 pixels is recommended although the emulator will run on 640x480 screens. MacFrodo will set your monitor to 256 colours automatically when you run it. For sound support, MacFrodo requires a PowerPC based Macintosh. How do I use it?The point of MacFrodo is to run old C64 software. The first step in doing this is to get hold of the program you want in .D64 or .T64 format. A large archive of C64 games is available at ftp://arnold.hiof.no/ on the internet. Unfortunately there is no easy way to insert your old C64 disks or tapes directly into the Macintosh. Once you have your image file, insert it into Drive 8 using the Insert Disk (or Insert Tape) command in the Drive 8 submenu of the Drives menu. Then, you should type LOAD"*",8,1 (note that this is the same for Tape or Disk images) and press return. With a bit of luck you should see a message SEARCHING FOR * followed by LOADING. When the ready prompt appears, type RUN and press return.If you cannot get your software (.D64 disk image) to work, you can try turning on the Better 1541 Emulation option. This slows down MacFrodo noticably but it increases compatibility with so-called Fastloading software. Note that all disk/tape images are ejected when you turn this option on or off, and that only Drive 8 will work in this mode.If the program still doesn't work, try using Frodo SC (see below).What is the difference between Frodo and Frodo SC?Frodo SC is a special version of Frodo that doesn't work with a line-based emulation but instead with a cycle-based one. That means that the emulator switches between 6510 and VIC in every emulated ø2 clock phase. By doing this, Frodo SC achieves an extreme precision (nearly all $d011 and $d016 effects can be emulated), but at the expense of speed (Frodo SC is considerably slower than regular Frodo).Frodo SC is operated in the same way as Frodo and also uses the same settings. Frodo SC has only a few incompatibilities to a real C64: • Color of $ff bytes read by VIC when BA is low and AEC is high is not correct • On the left and right side of the screen, sprites are not clipped but blanked out • Sprite collisions are only detected within the visible screen area (excluding borders) • The sprite data fetch ignores the state of BA • On BA low and AEC high, the VIC always reads $f in D8-D11 • Color register modifications are visible 7 pixels too late • Some opcodes like $8b/$ab don't create the same (partly unpredictable) results as on a real 6510 • BRK cannot be interrupted by IRQ/NMI • The TOD clock should not be stopped on a read access, but be latched • The SDR interrupt is faked • Some small incompatibilities with the CIA timers • The readable SID registers are not emulated correctly What about the keyboard/joystick mapping?The keyboard layout in MacFrodo is in the original C64 format. This can cause a bit of confusion for those who never had an original Commodore 64. The important keys (letters and numbers) are where you would expect them to be. The symbols are in different places however.One joystick is implemented, using the numeric keypad on the right hand side of your keyboard. The joystick port can be swapped using the Swap Joysticks menu item in the Options menu.F9 will open SAM, the built in Frodo Debugger. F10 and F11 will adjust the current frame rate. F12 will Reset the emulated C64.So, what do all the options do? Video: • Skip Every Other Line - This speeds up the drawing in double size mode. The speed gain is small but it is noticable, especially when a lot of things are moving on the screen. • Hide Menus and Cursor - With this option on (and Show Mac Desktop disabled) the entire Mac screen will be taken over by the emulated C64 window. • Show Mac Desktop - With this option enabled, the black background in double size mode is not drawn, so you can see other programs running in the background. Cycles: • Cycles per line (CPU) and Cycles per bad line (CPU) - This controls the number of clock cycles available to the CPU per normal raster line and per Bad Line. If a program is showing flickering lines or graphical flaws you should try slightly altering both values. For "Bruce Lee" you must enter "62" for the "Cycles per line (CPU)". • Cycles per line (CIA) - This is for controlling the speed of the CIA timers. Entering a higher value increases the frequency of cursor blinking and key repeat. Some programs don't run correctly with the default value (e.g. "Ballblazer" which needs a value of 65). • Cycles per line (1541) - This sets the number of cycles available to the 1541 processor emulation per raster line. There is normally no need to change this value. This setting has no effect if Better 1541 emulation is turned off.Speed: • Draw (n) Frames - Rendering every frame of the Commodore 64 screen, while providing much smoother graphics, does slow down the emulator. If the emulator is running at below 100% on your system you should set this option to skip some frames. This value can also be adjusted by pressing F10 (skip more frames) and F11 (skip fewer frames) while the emulator is running. • Show Speed Indicator - Appends a bar with the current emulator speed (% of original C64) and disk drive activity lights to the bottom of the emulator window. • Run at n% of Actual Speed - This option allows you to set the maximum speed the emulator will run at (between 20% and 500%). The current speed is visible in the main emulator window beside the disk drive indicator lights. The Video options tend to affect the speed which the emulator will run at on your computer.Emulation: • REU - This sets the size of the REU (RAM Expansion Unit) emulated by Frodo or turns the REU emulation off ("None"). Only few programs actually use the REU (operating systems like ACE and GEOS, and some utilities). • Sprites On - This allows you to switch the display of sprites on and off. Turning them off speeds up the emulation a little when there are a lot of sprites on the screen. • Sprite Collisions - This determines whether collisions between sprites and between sprites and graphics should be detected. Turning off collisions will make you invincible in some games (sadly, your enemies are likely to become invincible, too. • Fast Reset - This allows you to disable the memory test that
