The X68000 (Japanese: エックス ろくまんはっせん, Hepburn: Ekkusu Rokuman Hassen) is a home computer made by Sharp Corporation. It was first sold in Japan in 1987 and was not available outside of Japan.

The first version of the X68000 uses a 10 MHz Motorola 68000 processor and has 1 MB of RAM, but it does not include a hard drive. The last version was released in 1993 and includes a faster 25 MHz Motorola 68030 processor, 4 MB of RAM, and an optional 80 MB SCSI hard drive. The computer’s RAM can be expanded to 12 MB, but most games and programs only need up to 2 MB.

The X68000 has graphics technology similar to arcade video games from the late 1980s. Special chips help create scrolling images, tiled backgrounds, and many on-screen characters. Sound is produced using multiple chips that support 8 channels of FM synthesis and one channel of advanced sound technology. These sounds are combined into two analog stereo channels through a DAC chip. Because of its strong graphics and sound capabilities, the X68000 was often used for playing video games.

Operating system

The X68k uses an operating system named Human68k, which was created for Sharp by Hudson Soft. Human68k is similar to MS-DOS and uses English commands that work like those in MS-DOS. Files that can be run on the system have the .X extension. Earlier versions of the operating system only showed text for basic tools like "format" and "switch," while later versions included graphical forms for these tools. At least three main versions of the operating system were released, with additional updates in between.

Early models of the system used a graphical user interface called "VS" or "Visual Shell." Later models came with a different interface called SX-Window. A third interface, Ko-Window, was also available and had a design similar to Motif. These graphical interfaces could be started from floppy disks or the system's hard drive. Most games could be started and played from floppy disks, while some could be installed on the hard drive, and others required installation on the hard drive.

After the system was released, software such as Human68k, console tools, SX-Window C compiler sets, and BIOS ROMs were made freely available for download as public domain software. Other operating systems, such as OS-9 and NetBSD for the X68030 model, were also available for use.

Case design

The X68000 has two soft-eject 5.25-inch floppy drives, or in the compact models, two 3.5-inch floppy drives. The case has a unique design with two connected towers, separated by a retractable carrying handle. This system was one of the first to use a power switch controlled by software. When pressed, the switch tells the system's software to save and shut down. The screen goes black and the sound stops before the system turns off.

The system's keyboard has a mouse port on both sides. The front of the computer has a headphone jack, volume control, joystick, keyboard, and mouse ports. The top has a retractable carrying handle only on non-Compact models, a reset button, and a non-maskable interrupt (NMI) button. The rear includes many ports, such as stereoscopic output for 3D goggles, FDD and HDD expansion ports, and expansion slots for the I/O board.

Display

The monitor can handle horizontal scanning rates of 15, 24, and 31 kHz. It works as a television that can receive cable signals (NTSC-J standard) and has a composite video input. This monitor was a high-quality device for playing arcade games that use JAMMA-compatible boards because it has an analog RGB input and supports all three horizontal scanning rates used in arcade games.

Disk I/O

Early machines used a rare system called the Shugart Associates System Interface (SASI) for connecting hard disks. Later models switched to a widely accepted standard called the Small Computer System Interface (SCSI). SASI drives could be set up to hold 10, 20, or 40 MB of data and could be divided into separate sections called partitions.

The Human68K system does not support the long file names used in modern Windows systems. Instead, it uses file names with up to 18 characters, which is more than the 8-character limit of the older FAT file system. By default, Human68K ignores any characters beyond the first 8 unless a special tool is used. This means that files or folders with the same name when viewed using 8-character names but different names using 18-character names are treated as identical. The Human68K system treats uppercase and lowercase letters as different and allows filenames with lowercase letters and special Japanese characters encoded in Shift JIS. These features can cause problems when a DOS system tries to read such files.

If a user of the X68000 system limits filenames to the 8-character format used by DOS and uses only uppercase Latin letters, disks created on the X68000 will work with other Japanese systems like the NEC PC-8801, Fujitsu FMR, and FM Towns computers. The standard disk format used by the X68000 includes 77 tracks, 2 heads, 8 sectors, 1024 bytes per sector, and spins at 360 revolutions per minute, providing a total storage capacity of 1232 KiB.

Expansion

Many add-on cards were made available for the system, including networking (Neptune-X), SCSI, memory upgrades, CPU improvements (JUPITER-X 68040/060 accelerator), and MIDI I/O boards. The system has two joystick ports, both 9-pin male and supporting Atari standard joysticks and MSX controllers. Capcom made a converter that was originally sold packaged with the X68000 version of Street Fighter II. This converter allowed users to connect a Super Famicom or Mega Drive controller to the system. The adapter was designed specifically to let users connect the Capcom Power Stick Fighter controller to the system.

Technical specifications

• Main CPU: X68000 (1987) to SUPER (1991) models used the Hitachi HD68HC000 (16/32-bit) running at 10 MHz. XVI (1991) to Compact (1992) models used the Motorola 68000 (16/32-bit) running at 16 MHz. X68030 (1993) models used the Motorola MC68EC030 (32-bit) running at 25 MHz.
• Sub-CPU: Oki MSM80C51 microcontroller unit (MCU).
• GPU (graphics processing unit) chipset: Sharp-Hudson Custom Chipset. X68000 (1987) model used the CYNTHIA Jr/Sr Sprite Controller, VINAS CRT Controller, VSOP Video Controller, and RESERVE Video Data Selector. ACE (1988) to X68030 (1993) models used the CYNTHIA Sprite Controller, VICON CRT Controller, VIPS Video Controller, and CATHY Video Data Selector.
• Sound chips: Yamaha YM2151 (eight FM synthesis channels), Yamaha YM3012 (floating point DAC with 2-channel stereo output), Oki MSM6258 (one 4-bit ADPCM mono channel at 15.6 kHz sampling rate).

• ROM: 1 MB total (128 KB BIOS, 768 KB Character Generator).
• Main RAM: 1–4 MB (expandable up to 12 MB).
• VRAM: 1,056 KB total, with 512 KB for graphics, 512 KB for text, and 32 KB for sprites.
• SRAM: 16 KB static RAM.

• Color palette: 65,536 colors (16-bit RGB high color depth).
• Maximum colors on screen: 65,536 (in 512×512 resolution).
• Screen resolutions (all using the 65,536 color palette): 256×240 pixels (16 to 65,536 colors), 256×256 pixels (16 to 65,536 colors), 512×240 pixels (16 to 65,536 colors), 512×256 pixels (16 to 65,536 colors), 512×512 pixels (16 to 65,536 colors), 640×480 pixels (16 to 64 colors), 768×512 pixels (16 to 64 colors), 1024×1024 pixels (16 to 64 colors).
• Graphics hardware (VINAS 1 + 2, VSOP, CYNTHIA / Jr, RESERVE): Hardware scrolling, priority control, super-impose, dual tilemap background layers, sprite flipping.
• Graphical planes: 1–4 bitmap planes, 1–2 tilemap planes, 1 sprite plane. Bitmap planes: 1 layer (512×512 resolution at 65,536 colors on screen, or 1024×1024 resolution at 64 colors on screen), 2 layers (512×512 resolution at 256 colors per layer, 512 colors combined), 4 layers (512×512 resolution at 16 colors per layer, 64 colors combined). BG tilemap planes: BG plane resolutions (256×256 for 2 layers or 512×512 for 1 layer), BG chip/tile size (8×8 or 16×16), colors per BG layer (256). BG colors on screen: 256 (1 layer) or 512 (2 layers). BG tiles on screen: 512 (16×16 tiles in 256×256 layers) to 4096 (8×8 tiles in 512×512 layer). Sprite plane: Sprite count (128 on screen, 32 per scanline, 256 sprite patterns in VRAM, expandable to 512 with scanline raster interrupt method), sprite size (16×16), colors per sprite (16 colors from 16 palettes), sprite colors on screen (256), sprite tile size (8×8 or 16×16), sprite tile count (128–512 on screen, 256–1024 in VRAM).

• Expansion: 2 card slots (4 on Pro models).
• I/O Ports: 2 MSX compatible joystick ports, audio IN/OUT stereo scope/3D goggles port, TV/monitor control RGB/NTSC video image I/O expansion (2 slots), external FDD (up to 2), SASI/SCSI (depending on model), RS232 serial port, parallel port, headphone and microphone ports.
• Floppy Drives: Two 5.25-inch floppy drives (1.2 MB each).
• Hard disk: 80 MB (Sharp CZ-5H08), 81 MB (Sharp CZ-68H), 160 MB (Sharp CZ-5H16).
• Operating systems: MS-DOS, CP/M, and others.
• Power: 120 V AC.
• Weight: Not specified

Legacy

In 2022, ZUIKI Inc. announced a preview of a new small console named the X68000 Z, which is a smaller version of the X68000.