To the question: What's an emulator? I would answer:
![]() IntroductionIf you spent your childhood afternoons on a computer using a cassette recorder or an unreliable floppy disk connected to a kind of computer, you've got for sure an interest for the emulators.
Executor is a software application that allows Motorola 68000-based classic Mac OS programs to be run on various x86-based operating systems. Executor was created by ARDI (Abacus Research and Development, Inc.). It emulates a Macintosh 128K, Macintosh 512k, Macintosh 512ke or a Macintosh Plus. PearPC: PearPC is the first free, open source PowerPC Architecture emulator out there, and it seems to have made great progress so far. Though not ready for stable usage, it can run Mac OS X 10.3 more or less. SheepShaver: SheepShaver is a PowerPC emulator written by Christian Bauer.
If you've got an Amiga, and your sadic teachers and supervisors demand that reports from you are typed with micro$oft Word, you should also be interested by emulators, at least for the following reasons:
Usefulness of such software8 bit emulatorsIt's good to be able to play Lode Runner or Zorgon's Revenge on your amiga,but that's not very constructive. It is pure nostalgy, and nowaday's gamesare much better, most of all those using mapped 3D with 16 billons of colors,THX sound, dolby surround with the pentium processor directly connected to the CD-ROM 24x on internet thank you intel.
And even on Amiga, the games are better (not those from US Gold).
Nowaday's Amigas are able to emulate 8 bit computers with a decent speed,so the games are very playable. However, I know no tool which is absolutelynecessary and which only runs on a 8 bit cpu (maybe BASIC).
16-32 bit emulationIt's serious matter. This kind of emulator is generally
![]() Macintosh EmulationOn Amiga, it's 'easy' (if I dare), because the 680x0 processor needs not to be emulated, and -funny fact- Shapeshifter allows to run Mac system with a 68060, which provides the fastest Mac on the market (don't talk me about the PowerMac, half of the current software are emulated).
On the Amiga, Shapeshifter blasted its competitors by its impressive functionalities
As I say, Shape (may I call you Shape?) is excellent. Once in the world aguy makes money with computer software without being called bill. He deserves it.Moreover, the author is not greedy, as he also wrote a very good and totally free C64 emulator, including source code.Finally, he's a bit like bill, who gives explorer for free...
Such a nice guy.
Let's mention the amazing speed of Executor on PC (yes) which performs dynamic compilation from 68000 to i386. Very impressive.The only problem is that Executor authors re-wrote the Macintosh ROMs(for better speed, and maybe also for a copyright problem) based on system6.5, and that means you can't make the OS evolve.
But anyway that's a beautiful program. PeeCee emulationThe PC-Task and PCX emulators are well programmed, but are a bit uselessbecause games are unplayable because too slow (or the amiga version exists)and the macintosh emulation can handle 'serious' applications (such as M$-Office or Works), and other well-known ones (Photoshop, Netscape) at avery good speed.
Really, except for some old Pascal program the sources of which you've lost, really I can't see any interest.
Or you are PC-addicted. In that case, buy a PC and stop breaking balls.
Atari ST emulationWho does not know the Amiga big brother, in the same frame of mind, but without the highly superior Amiga hardware, with the ugly us gold games, but also with unique software like Cubase, Studio 24 or Colonial Conquest and Super Sprint?
It's hard to code a ST emulator which would be both fast and compatible with games.
Actually, I doubt that any emulator can run any arcade game (the ones which trash the system and use their own code) when the code is not interpreted but runs freely, like in the Macintosh emulators.It's easier to achieve on a Mac because the OS is almost impossible to bypass.
Anything considered, there is no ST emulator on Amiga for the processorshigher that the 68000.
Amiga EmulationUAE taken apart, I cannot see one. UAE is *amazing*. A huge work, an impressive programmers coordination, excellent compatibility, even with the oldcrappy-programmed-by-pitbulls us gold software, or the ones with very special space tricks to improve scrolling smoothness with bitplane change at line 120, and sound modulation using the floppy controller in DMA.For the Unix/Linux version, the interest is obvious: play again at games not released on PC, and play at decent games on workstations.(with a SGI Impact 10000, I can say that the speed is good).
If you run UAE under Linux and you reduce the screen resolution to 320x200,you nearly beleive you're on amiga.
I'm impressed.
And the amiga version, dummy?
Okay, I was talking about the Linux version, which now features sound, AGA modes, FPU emulation, 68020 CPU emulation, and dynamic compilation if that was not enough. We would never have thought about it a few months ago.
There had to be a mad man in this world to port UAE on amiga, and Samuel Devulder played that part. Even if the emulation is less performant (because of the planar display, because of the C slowness, because of problems ofporting Unix -> AmigaOS), it's still great work, and this could evenbe a path to the new Amiga generation based on PPC (do you really beleivethere will be another Amiga generation?)
How it worksI see you're doubting about my abilities to explain how all this work.I can do it.The displayThe method is roughly speaking the same for all emulators: they refresh the screen by a timer interrupt and convert the virtual video memory (of the emulated computer) to display the picture on the amiga screen.
For sure it will be slow, except if we forget to be stupid:
The processorIf both machines (emulated and amiga) use the same processor, then the only method is to redirect the system calls connected to low level ressources,like sound, floppy disk, SCSI ports, parallel and serial ports.
Macintosh emulators manage very well with this technique, but the problems begin when some 'wicked' software (like there are thousands on the Amiga) use hardware banging in the hardware registers, bypassing the system interfaces (the devices, on amiga).The emulator does not notice those accesses and it can crash nastily, except if the emulator uses MMU to catch those accesses (not done on Shapeshifter,which would explain why some games crash, but I think it is done onA-Max IV).
If both don't have the same CPU, then, the emulator has to 'translate' thebinary code in 68000 assembler, either in an interpretive way (rather easy), or by dynamic compilation (very hard, but very efficient, except for self-modifying code).
Dynamic compilation is only worth if we want to emulate a powerful computer, like a 32 bit architecture. For 8 bit machines, it's of minor interest, and moreover problems could appear due to the rudimentary operating system of those computers. Actually those 'OS' assume that the speed of the processor isconstant, and some timing problems could occur: real time clocks, keyboarrrrrrrrrrrrrrrrrrd...
PeripheralsLow-level emulation is more suitable for 8 bit emulations than high level emulation (i.e. patching the OS routines that access hardware registers), ina compatibility issue (c.f. Frodo by C. Bauer versus A64).
Indeed, old games and applications wildly poke into the hardware registers, even if they use BASIC.
Conversely, for a 16-32 bit emulation, it's better to catch the system calls at a higher level because only a few programs use low level calls (virus...), and MMU traps can complement the low level accesses.
Speed is better if system calls are trapped at a higher level (e.g: read a block on a SCSI disk).
Shapeshifter reaches a very good speed using this method, but Macintosh is abit special, as programmers generally respect programming guidelines (not exactly true on the amiga).
You have been had, confide it.
Okay, I stop those stupid technical details here.
Available emulators on the AmigaI gathered here the emulators I knew for our great computer. For the ones I don't know, I cannot do so.If you know some other one, or the information I'm providing is inaccurateor wrong, don't hesitate to contact me for a correction. I won't feelannoyed.
For C64 ROMs, you can get the PC64 emulator (for PC) and install it: the ROMs are provided. What about the WEB?That's a online fanzine, so I have to talk about the Web.
I gathered for you some cool URL's. You'll thank me later.
Some interesting newsgroups
![]() As a conclusionWell, I hope I did not bother you too much. In the other case, the 'HOME' button will get you outof here.
See you lads.
(Redirected from VMac (emulator))
vMac 0.1.9 running System 1.1 on System 7.5
vMac was an open source emulator for Mac OS on Windows, DOS, OS/2, NeXTSTEP, Linux-Unix, and other platforms. Although vMac has been abandoned, Mini vMac, an improved spinoff of vMac, is currently developed. vMac and Mini vMac emulate a Macintosh Plus and can run Apple Macintosh System versions 1.1 to 7.5.5. vMac and Mini vMac support CPU emulation from Motorola 68000 to 68040, display output, sound, floppy disk insert, HFV image files, and more. Some vMac ports include extra features such as CD-ROM support, basic serial port (SCC) support, Gemulator ROM board support, and various performance improvements. Although the website is still in operation, most vMac development slowed to a halt in 1999, and no official releases have been made since. Many of the developer e-mail addresses listed on the website are not currently working.
Overview[edit]
Mini vMac, vMac's spinoff, is still being maintained and developed by Paul C. Pratt. Currently Mini vMac supports Macintosh 128K, 512K, 512Ke, Plus, SE and Classic, with active development for Macintosh II, Macintosh Portable and PowerBook 100 support. Due to complaints about the rarity of the original II,[citation needed] it also accepts Macintosh IIx and Macintosh SE/30ROM files. The precompiled versions available for download at Mini vMac's SourceForge project emulates a Macintosh Plus with 4 MiB of RAM.
vMac and Mini vMac require a Macintosh Plus ROM file and Macintosh system software to work. Macintosh ROM files are owned by Apple and cannot be legally distributed. However, the Windows and Unix ports of vMac (not Mini vMac) support the Gemulator ROM board from Emulators Inc., which allows users to add genuine MacPlus ROM chips to their x86 machine via an ISA expansion slot. This board can also support ROM chips from other early Macintosh systems, but the publicly released versions of vMac only supported the Macintosh Plus. Macintosh system software is available from Apple's Support Downloads Website (see External links below).
As mentioned, Mini vMac also requires a specific ROM image for the computer emulation desired. A software application for these 68000 Macs may be downloaded from the Mini vMac website for retrieval of a system's ROM image, along with a complete tutorial for locating an old Mac, retrieving the ROM and working with disk images.
See also[edit]
External links[edit]
Retrieved from 'https://en.wikipedia.org/w/index.php?title=VMac&oldid=916416275'
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