When released in September 1992 at the Glendale Atari Fair in California, "Gemulator" was the world's first Atari ST emulator for the PC. Written in almost nothing but 486 machine code, Gemulator 1.0 was capable of running Atari ST software at full 68000 speeds on Intel 486 based MS-DOS computers. Gemulator was upgraded in 1993 to add emulation of Apple Macintosh Plus computers running Mac System 6. This was followed in 1995 with releases to run on Microsoft Windows 3.1 and Windows 95. In 1998 we added support for Windows 98 and NT 4.0, and spun off a sister product called "Gemulator SoftMac" (or simply as "SoftMac") which added the ability to emulate 32-bit color Mac models such as the Macintosh II and Macintosh Quadra. On November 30 2008, Gemulator 9.0 was officially released, supporting a built-in 68000/68030 debugger, improved compatibility with Windows Vista and recent multi-core 64-bit processors.

Download Gemulator (releases and betas)

Product Features

Hardware and Software Requirements

Speed and Compatibility

Installing Gemulator

Configuring Gemulator

Using Gemulator

SoftMac Documentation

Product Features

All versions of Gemulator released since 1992 share a common set of features:

• 520ST/1040ST hardware emulation.

• Motorola 680x0-series CPU emulation.

• 512K to 4M of emulated Atari ST memory.

• ST Low (320x200 16-color), ST Medium (640x200 4-color), ST High (640x400 monochrome) graphics support.

• Modem, printer, and sound support

• 720K and 1.44M floppy disk support, able to read Atari ST formatted floppies

• Atari ST hard disk support (via VHD disk image files)

• Mouse and keyboard support

• Support for TOS 1.0, TOS 1.2, TOS 1.4, TOS 2.06, and MagiC

With all versions of Gemulator, you can run most of the major desktop publishing, graphics, word processing, and finance software written for Atari ST computers. For example, you can edit and run your GFA Basic programs, run Pagestream and print your documents, run Calamus SL and print your documents, query your Data Manager ST databases, write documents with Word Writer ST, draw graphics with Degas Elite, run some old Macintosh software using Magic Sac, and most other things you do on an Atari ST computer.

Windows-hosted releases of Gemulator add additional capabilities that go beyond those of the original MS-DOS version:

• STE emulation, support for STE-only TOS (TOS 1.6, TOS 1.62, and TOS 2.05)

• 800x600, 1024x768, 1280x1024, and 1600x1200 video modes

• Full screen and windowed modes of operation

• up to 14 megabytes of Atari ST memory

• Support for very large hard disk partitions, CD-ROMs, and network drives

• external SCSI hard disk support

• Easy-to-use point and click configuration

• Black and white Macintosh Plus emulation with support for System 6 and System 7

Gemulator 9 and Gemulator SoftMac releases add these Macintosh related features:

• Selectable 68000, 68010, 68020, 68030, and 68040 emulation

• 68881/68882 floating point co-processor emulation

• Apple Macintosh II, Macintosh IIci, and Macintosh Quadra emulation

• Built-in 68000 debugger and third party debugger support

• Support for the open source Atari TOS ROM clone known as "EmuTOS"

Gemulator's main limitations are that copy protected floppy disks are not supported, MIDI ports are not supported, and timing dependent software is not supported. For example, programs such as Spectrum 512 which run only on 8 MHz Atari ST models, but not on 16MHz STE or 32 MHz TT models will not run on Gemulator either. This is because Gemulator typically runs much faster than the standard 8 MHz speed of an ST.

For specifics about running Macintosh applications and Mac OS, please see the SoftMac page.

High resolution graphics

Gemulator takes advantage of the higher graphics resolutions available in your PC's video card. In addition to emulating the 3 standard Atari ST screen resolutions (320x200 in 16 colors, 640x200 in 4 colors, and 640x400 monochrome) Gemulator also supports 640x480, 800x600, 1024x768, and 1280x1024 in monochrome and 16-color modes. Note: Gemulator Classic is limited to a maximum 640x480 resolution.

More memory than a real ST

Gemulator can emulate a 520ST, a Mega ST 4, or a MegaSTE with up to 14 megabytes of memory (8 megabytes on Gemulator Classic for MS-DOS). The amount of memory being emulated can be set at 512K, 1 meg, 2 meg, 4 meg, 8 meg, or 14 meg, and can be changed at any time while running Gemulator.

Disk support

Access your Atari single sided 360K, double sided 720K, and high density 1.44M floppy disks, as well as 800K disks and boot disks. Gemulator can even read those old TOS 1.0 formatted floppy disks that PCs normally can't read.

Note: Copy protected floppy disks are not supported. Windows 3.1 and Windows NT do not support the TOS 1.0 formatted disks.

Gemulator 2000 also automatically accesses all the hard disk partitions and CD-ROM drives connected to your PC. Earlier versions of Gemulator required setting up separate Atari ST hard disk partitions, and while this is still an option it is no longer required. Gemulator automatically takes care of large hard disk partitions, Stacker and DoubleSpace partitions, and other hard disk formats that TOS did not originally support.

That's right: Gemulator 2000 eliminates GEM's 32 megabyte partition size limit!

MFP, Yamaha, video, DMA, and Blitter chip support

As mentioned earlier, Gemulator is not only a complete 68000 emulator, but it also emulates all of the special hardware chips used inside Atari ST computers. This includes the video chip, so that programs which write directly to screen memory run just fine. NVDI 4, Warp 9, Quick ST 3, Turbo ST, and other screen accelerators are fully supported.

Multiple modem and printer support

Atari programs can access any printer or modem that Windows supports. You can switch between them on the fly, by specifying which COM port and which LPT port to use as the Atari modem and printer ports. On Gemulator 96, modem baud rates beyond 19200 baud are also supported, including 28800, 38400, 57600, and 115200 baud.

Hardware Requirements

Gemulator supports a combination of plug-in hardware called the "Gemulator ROM card" which holds actual ROM chips, ROM BIOS image files which contain "ripped" BIOS ROMs in a disk file, and disk based operating systems such as Atari's TOS 1.0, the TOS replacement "Magic", and various release of Mac OS.

The hardware portion is an 8-bit ISA card that includes the Atari ST or STE TOS ROMs. The card plugs into any empty ISA slot in your PC or docking station. One or more sets of Atari ST or STE TOS ROM chips and/or Apple Macintosh Plus ROM chips must be plugged in to the card to operate, since it is these ROMs that contain the boot code to an Atari or Macintosh operating system.

You can eliminate the ROM card and real ROMs by using what are called ROM image files. These are ROM dumps created on your real Atari ST or Apple Macintosh computer. In place of Atari ST ROMs you can also use a TOS compatible Atari ST operating system such as MagiC 2, MagiC 4, MagiC 5, KAOS TOS, or an early disk release of TOS 1.0 or TOS 1.4. A TOS ROM image file should be named TOS.IMG and placed in the same directory as the Gemulator program.

Up to four 2-chip sets of TOS ROMs may be plugged in to one Gemulator card, or a combination of one 2-chip and one 6-chip set of ROMS as shown in the picture. You may also plug in a 2-chip set of 64K or 128K Mac ROMs which can be found in old Magic Sac and Spectre cartridges.

Up to 50 sets of ROM BIOSes can be installed simultaneously in your PC, using a combination of one or more ROM cards and ROM image files. Up to 8 ROM cards can be plugged in to one computer at once provided there are enough ISA slots available.

If you do not have a way to create a ROM image file, you will need to obtain a ROM card and populate it with your own ROM chips. The ROM card can accept all types of Atari ROMs from the 520ST, 1040ST, 1040STE, Mega ST, Mega STE, Macintosh 512, and Macintosh Plus. The card also accepts other ROMs which are not supported by Gemulator 2000 directly but can be used by SoftMac 2000 and other emulators.

The TOS ROMs come in sets of 2, 4, and 6 chips, in either 28-pin or 32-pin packages. If you don't have loose ROMs but have an Atari computer, unscrew the cover from your Atari and find the ROMs on the motherboard. If your Atari ST computer has a 6-chip set of 28-pin ROMs, those can be used, as can 2-chip sets of 32-pin ROMs from an Atari STE or Mega STE computer. Each ROM will either have a part number stamped on, or have a label taped on top. The following is a list of North American Atari TOS ROMs and part numbers that we've cataloged so far that we support.

Atari TT ROMs come as a 4-chip set of 32-pin ROMs. Those ROMs will be supported at some future time.

Some Atari ST ROMs come as a 2-chip set of 28-pin ROMs. Those ROMs are not supported at this time due to differences in pin layout of those particular ROM chips used.

Macintosh 512 and Macintosh Plus ROMs come as a 2-chip 28-pin set and are supported. 4-chip sets of Macintosh ROMs (Macintosh II and higher) require using SoftMac 2000 or later. See the Macintosh ROM Chart for a list of compatible Mac ROMs.

Software Requirements

Gemulator 2000 runs on all DirectX compatible versions of Windows - Windows 95, Windows 95 OSR2, Windows 98, Windows NT 4, and Windows 2000. It runs on all Intel 486 compatible 32-bit processors (486, Pentium Classic, Pentium Pro, Pentium MMX, Pentium II, Pentium III, AMD K6, AMD K7 Athlon). Gemulator is Pentium optimized and mostly written in Intel assembly language to provide up to 5 times the speed of other Atari ST and Macintosh Plus emulators, and runs up to 50 times faster than real Atari ST and Macintosh Plus computers.

Gemulator 2000 supports disk images, both for floppy disks and hard disks. Use .ATR, .XFD, .ST, .MSA, .DSK, .IMG, .VHD and other disk image formats directly with Gemulator! Gemulator 2000 also supports direct connection of Macintosh and Atari SCSI devices such as ZIP disks, Jaz disks, and CD-ROMs via the PC's SCSI bus.

Speed and Compatibility

Speed

The faster your PC's processor, the faster Gemulator runs. Which processor you should use depends on how fast you need for your Atari software to run.

For 1040ST and Mega ST speed of operation, we recommend using a 486/33 or 486/50 processor. For Falcon or TT speed of operation, you will need to use a 75 Mhz or 90 Mhz Pentium as a minimum. Faster Pentiums scream.

These recent screen shots taken with Gemulator 96 (ok, we haven't updated this for Gemulator 2000, just know that the numbers will be faster!) show Gemulator running at blistering fast speeds on a 200 MHz PC. The screen shot on the left is using regular TOS 2.06 ROMs. The screen on the right shows the same benchmarks when using the MagiC operating system. If you have a newer PC running at 500 MHz or 800 MHz, your speed will be proportionally faster!

15 times faster than an original Atari 1040ST!

Compatibility

Gemulator runs almost 100% of ST and STE software at full Atari ST speed or faster. Only copy-protected and timing dependent Atari programs are not supported - programs that typically also do not run on Mega STE, Falcon, or TT computers either, or programs that make use of MIDI or joystick ports. Most MIDI programs in particular are heavily copy protected, which has made it difficult to add this feature.

Popular Atari programs that have been tested and run on Gemulator include:

Calamus / Calamus SL
Pagestream 2.1
GFA Basic
Tempus / Tempus II
Word Writer / First Word Plus
Atari Works
Multi Writer
Flash! / Flash II
Megamax C / Laser C
Neodesk 4
Quick ST / Warp 9 / NVDI
MagiC operating system
Data Manager ST
Phasar
Speedo GDOS
and many more.

Please note. This is NOT a complete compatibility list by any means. Nor do we even maintain such a list since we cannot possibly purchase and test each and every Atari ST program ever written. Our testing, and user feedback, of hundreds of different Atari ST and STE programs has confirmed that most compatibility problems are due to copy protected or timing dependent software.

Gemulator is ideal for running Calamus SL and Pagestream, because it offers the ability to load your existing desktop publishing documents on Windows 95, to use 1600x1200 graphics, and to use up to 14 megabytes of Atari ST memory doing it. Such a system using real Atari TT computers would cost about $3000. A Pentium based Windows 95 system capable of running Gemulator with these capabilities costs half as much.

Configuring GEMULATOR

The very first time that you run Gemulator you may be prompted with a First Time Setup dialog box. This is a one time procedure that tells Gemulator what port address the ROM card can be found at, and whether to scan the hard disk for disk based versions of TOS and any ROM image files. Gemulator will search for Atari and Macintosh ROM image files in the same directory as Gemulator itself.

Assuming that the ROM card is at address $240, you can select the Search ROM Cards option then click the Search button. If you have installed MagiC or TOS on floppy onto the hard disk, also select the Search Hard Disk option. If no ROMs get detected, click on the Settings button. You will get the ROM Card Settings dialog.

Make sure that the port address is set correctly and that the switch settings shown in the dialog match the settings on the card. When the address is correct, click the Scan button. The contents of each ROM socket will then be shown. Make sure that TOS ROMs do not appear in the wrong order or that sockets that contain ROMs don’t show as empty. If they do, shut off your computer, take out the Gemulator ROM card, and check that you installed the ROMs correctly.

Click Close to return to the First Time Setup dialog. When ROMs and/or ROM images are being detected, click the Close button again.

The next step is to customize Gemulator using the Properties dialog box. This dialog contains the important configuration controls for Gemulator. It works just like any other Windows dialog. You can get directly to this dialog by pressing Alt + F11.

When you have made your changes you can activate them by clicking on the OK button; if you want to abandon your changes click on Cancel. Click on Save to save the current set of Gemulator settings to disk. They will be the default settings next time you run Gemulator.

The following is a description of each of the various properties:

Using GEMULATOR

When booting in Macintosh mode, make sure that at least one of the Mac disk drives is configured with a bootable disk image or device. SCSI devices such as Mac formatted CD-ROMs, Mac ZIP disks, and even external Mac hard disks can be booted from and accessed.

Exiting Gemulator

Gemulator can be terminated in several ways:

Using the Windows mouse pointer and click on the close box, that big X in the top right corner of the Gemulator window.

If you have a Windows keyboard, press the Menu key to bring up the Gemulator main menu and either press Alt+F4 or click on Exit.

If you have a regular keyboard, press Control+F11 to bring up the Gemulator main menu then press Alt+F4 or click on Exit. All unsaved work will be lost, so it is best to do this from the Atari ST desktop when no programs are running or one the Mac OS has been shut down.

Mouse Pointers

Since both Atari ST and Macintosh use graphical operating systems that make use of the mouse, it isn’t possible for both them and Windows to have control of the mouse at the same time. When you first start Gemulator you will find that you have two mouse pointers on screen! The working one will be the Windows mouse; the second, stationary, one is the emulated computer’s mouse.

In order for Gemulator to get control of the mouse, click the Windows mouse pointer anywhere on the Gemulator window. If you need to get the Windows mouse pointer back, simply press the F11 key, or press both mouse buttons at the same time.

The Atari ST mode supports these keyboard shortcuts for mouse actions:

• Alternate + cursor keys Move mouse

• Alternate + Shift + Cursor keys Fine mouse movements

• Alternate + Insert Left mouse button

• Alternate + Home Right Mouse button

Special Keystrokes

The following keystrokes have special meaning in Gemulator:

• Ctrl+F11 Brings up the Gemulator main menu dialog

• Alt+F11 Brings up the Properties dialog box

• Shift+F11 Brings up the Disk Properties dialog box

• Ctrl+F12 Reboots the emulated computer

• Alt+F12 Reboots and switches modes

• Shift+F12 Reboots and switches monitor types

• F11 Shows the Windows mouse

• Page Up Atari ST Help key

• Page Down Atari ST Undo key

• Home Atari ST Clr Home key

• Alt Macintosh command key (Apple logo key)

• Ctrl+F10 Switches Atari 8-bit mode (800, XL, XE)

• Shift+F10 Toggles Atari 8-bit BASIC cartridge

• F10 Atari 8-bit System Reset key

Atari ST TOS 2.06

TOS 2.06 is the latest, fastest, and least buggy version of Atari ST and STE TOS produced by Atari. It also has some new features not found in TOS 1.0, TOS 1.04, TOS 1.6, or other earlier versions of TOS. Icons can be dragged to the desktop. Disk directories can be opened by pressing Alt and the drive letter. The desktop settings are stored in the file NEWDESK.INF instead of the older DESKTOP.INF.

If you have TOS 2.06 installed, the Atari ST desktop does not immediately show up. Instead, an Atari logo appears, followed by a memory test, followed by a 90 second countdown which shows a large black bar on the screen. This countdown was added to TOS to give hard disks time to spin up. Since your PC’s hard disk is already up and running, and your PC has already performed its own memory test, you can safely skip both the memory test and the countdown by simply pressing any key on the keyboard when you see the logo.

Once the GEM desktop is up, you can use the keyboard to open disk drive directories. Just press Alt and the drive letter at the same time.

If you have TOS 2.05 installed, the logo is not displayed but the countdown still takes place. Although you will see just a white screen during the countdown, you can just press any key to skip it.

Accessing Atari ST Formatted Floppy Disks

Old versions of TOS had a bug that caused them to format floppy disks incorrectly. This bug prevented IBM PCs from reading Atari floppy disks, even though Atari computers could read MS-DOS disks.

The problem was corrected in TOS 1.4 and later versions of TOS. However, you may still have some disks formatted the old way.

There are three ways to read information from such disks:

1. Format a blank disk on the PC and then use your Atari computer to copy the files from the old disk to the new disk. Once copied, reformat all your old disks.

2. Activate the Atari Disk Mode option in Gemulator 98. This will allow Windows 95 to read the Atari disks and you can then use the PC to copy the files from these disks onto freshly formatted disks. Note: this trick only works on Windows 95. Windows 3.1 and Windows NT are more picky and can only read real MS-DOS disks.

3. Use an Atari ST utility such as DC Formatter or MOSDOS to re-write only the boot sector on the floppy disk. This fixes the disk without reformatting or losing any information. We supply the utility MOSDOS in the UTIL folder of the Gemulator 98 program disk.

Don't forget that you can run multiple copies of Gemulator at the same time. Of course this uses up a lot of memory, so make sure you have enough swap file space and preferably at least 12 megabytes of physical memory before attempting this. Use the Import Settings menu command to load a different configuration into each instance of Gemulator to emulate different computers with different configurations all at once.