MEGA65 quickstart
Click here to access the MEGA65 help summary main page
Foreword: if you're in hurry, you can more-or-less read only the bold style text in this page and follow those advises.
Since Xemu/MEGA65 emulates the MEGA65, it must reflect one of its key features as well, the usage of an SD-card. Thus, for usable MEGA65 emulation you need the emulation of an SD-card, in the form of an (at least 4 Gbytes long) SD-card image file with the proper content, more like a real MEGA65 needs a real (at least 4 Gbytes long, SDHC) SD-card with the expected content. However preparing a proper SD-card image can be problematic for newcomers (since it’s not a “real” card), thus there is some helper functionality in Xemu/MEGA65 to ease this process.
This description applies to first-time users who doesn't have any Xemu/MEGA65 configuration yet, thus emulation is not yet possible. As every computers (including emulated computers) need some initial code to be run after power on situation (often stored in ROM), with specific computers also need a prepared media where system software / OS can be "booted from". MEGA65 being more complex than an average 8 bit class machine also needs the latter.
This chapter does not deal with these issues, and assumes you have the emulator already. If you need the emulator itself, you can download from: https://github.lgb.hu/xemu/
Note: if you compiled Xemu by yourself for UNIX systems (including Linux) you may not have menu support (the right click thing) if you didn't have GTK3 development libraries installed at the compilation time, or Xemu has failed to detect it (on Mac and Windows, Xemu uses native APIs of those OSes, so you don't need GTK3 there).
Visit this page to learn more about this topic: MEGA65 ROM "how to get it" tutorial for Xemu
If you installed wrong ROM version, or you decide later, to use another ROM, you can do it. See later, it's selecting "Disks >> SD-card >> Update files on SD image" from the menu (beware, it replaces your default D81 as well).
It's important to remember, that accessing Xemu's menu is done by right mouse clicking into the emulator window. Left click will does something different: it grabs your mouse and enter into mouse emulation mode (you can cancel it with pressing both SHIFTs together on your keyboard). Though in newer Xemu builds, mouse grabbing is disabled by default since it causes some unwanted surprise for many people (you can still enable it via the menu, if you really need mouse emulation as well).
After launching Xemu/MEGA65 at the first time you'll prompted with a question if it's OK to create a 4Gbyte sized SD-card image file for you. Note, as it's written before, it's a must, as MEGA65 based on the SD-card presence, thus an emulated SD-card. Even if you think 4Gbyte is too much space, it won't work otherwise, this is the only way. Also please note: on most modern OSes the image file itself is a so called "sparse file" which means, it really does not take 4Gbyte disk space, even if you see its length is 4Gbyte.
In nutshell, you must allow Xemu to create the SD-card image file at this point to be able to continue.
In technical terms, on a real MEGA65 you would need to partition and format your SD-card, then put some specific files onto it, including some files from the MEGA65 project (which are open source, free software in the sense of GNU/GPL license) and the C65 ROM (which is not free software at all). In case of an emulator, it's even a more complicated task involving dealing with SD-card image file, rather than a "real" SD-card.
Xemu offers two useful functionalities built-in to help you here. It's provided as two menu options.
Right click into the emulator window causes a pop-up menu appearing
You must select "SD-card >> Re-format SD image" (that is, in the "SD-card" submenu) which does the fdisk/format work for you automatically
At this point, you need to do only one thing, to install/update the needed files on the SD-card image.
Select the "Disks >> SD-card >> Update files on SD image" menu point this time. It will asks for the ROM image, you have already downloaded
Beware, this replaces your default D81 as well
This latter functionality uses your provided ROM image to put onto the SD-card, also with several other files which can be provided by Xemu itself, since the lack of any legal/license problem (ie mega65-core components).
After this step, your MEGA65 emulation should work basically. Note, that you can use these functions of Xemu later as well, but surely, formatting the disk image causes ALL data and settings destroyed which was stored on your SD-card (in case of emulation, the image file of the SD-card). However, updating files (the second functionality I've mentioned) can be used later as well, to update "system files" you can have several reasons to do that:
- New version of Xemu, not compatible with old system files, so you need to update those (but probably not format/fdisk again)
- Other version of C65 ROM you want to use/try
However, it's important to mention, that even the default D81 on your SD-card image is overwritten, be careful with that, if you saved something onto the default "mounted" D81 (drive 8)!
Your selected ROM image is saved as file MEGA65.ROM in the so called preferences directory of the emulator which is also the default directory open when asked for the ROM. Thus, if you need later to repeat the updating files process, you can simply select MEGA65.ROM from that directory instead of your download one. Surely at the first time, it does not apply, since you haven't specified any ROM images yet.
