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Sharp X68000

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Sharp X68000
Sharp X68000 CZ-600C opened (Dave Jones)
A black CZ-600C with its main board K5023DE (left) and video board K5024DE (right) taken out (photo: Dave Jones, CC BY 2.0)
Specifications
ManufacturerSharp
TypePersonal computer
ReleasedMarch 1987[1]
Intro price¥369,000[2]
CPUHitachi HD68HC000 (68000) at 10 MHz[1]
Memory1 MB, expandable to 12 MB[1]
StorageTwo 5.25-inch 2HD floppy drives (1 MB); SASI hard disk port[1]
DisplayUp to 768 × 512; 65,536 colours at 512 × 512[1]
SoundYamaha YM2151 FM, OKI MSM6258 ADPCM[1]
Power100 V AC, 50/60 Hz; 44 W (10 W or less on standby)[3][4]
Dimensions155 × 363 × 270 mm (main unit)[3]
Weight7.7 kg (main unit)[3]
OS / FirmwareHuman68k[1]
SuccessorSharp X68000 ACE
Model no.CZ-600C (CZ-600CE grey, CZ-600CB black)

The Sharp X68000 (model CZ-600C) is a 68000-based personal computer that Sharp sold in Japan from March 1987.[1] It was the first of the 20 models Sharp sold in the X68000 series up to 1993.[1] The machine has two towers joined at the base: one holds the two 5.25-inch floppy drives and the power supply, the other holds the main board and two expansion slots.[4] The keyboard, mouse and display are separate.

The CZ-600C's power supply was used in no other model, and its boards carry different part numbers from those of the ACE that replaced it.[5][2][6] The repairs that owners have written up for it concern leaking electrolytic capacitors, the memory backup cell on the main board, and the floppy drives.[2][7]

History

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Sharp announced the X68000 in 1986 and put it on sale in March 1987 at ¥369,000, with the arcade game Gradius supplied.[1][2] It was first sold in grey (CZ-600CE). A black version followed in November 1987.[2][4] The Sharp X68000 ACE replaced it in March 1988.[1]

Hardware

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Boards

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The right-hand tower holds two boards. The main board, K5023DE, carries the CPU and DMA controller on a raised sub-board, the sound section and the Sharp custom chips ET, BUDDHA, CYNTHIA and CYNTHIA JR. The video board, K5024DE, carries the video RAM and the custom chips VINAS1, VINAS2, VSOP and RESERVE.[8][9][10][11][12] Poe's repair notes list the other boards: K5026DE for the expansion slots, K5027DE for the interface board and K5028DE to K5030DE for the lamps on the two towers.[2]

Poe describes two production lots. Early grey machines have parts marked RH-IX0898CEZZ and RH-IX0897CEZZ, an extra half-height board level in the right tower, and a crystal oscillator mounted upright. Later lots have IX0898CE and IX0897CE and the oscillator lying flat, where electrolyte from the backup cell can reach it.[2]

The 1 MB memory expansion for this model, CZ-6BE1, fits on the main board; it has to be fitted before any larger memory card in an expansion slot is added.[2][4]

Power supply

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The power supply sits in the drive tower (on the left seen from the front), beside the floppy drives.[8] The unit in Dave Jones's teardown is labelled UADP-0047CEZZ.[13] It runs from 100 V mains and was used only in the CZ-600C. The machine draws 44 W, or 10 W or less on standby.[3] The rear panel carries the main power switch, the mains inlet and a switched 100 V outlet rated at 300 W for a display.[14][5][4] The tower models have a front power switch and a main switch on the rear, and the machine can switch itself on and off under software control.[4] With the main switch on, a signal on the REMOTE connector can also switch it on.[14]

Floppy drives

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The two 5.25-inch 2HD drives eject discs with a motor, and each slot has an EJECT button beneath it.[4][8] A DISK EJECT button on the rear forces a disc out when it will not eject normally.[15] Poe re-greased the eject motor and its gears when he serviced the drives.[2] Poe lists the CZ-600C drive unit as K-61432-71, built only for this model, with a Seiko Epson SST-20C120L stepping motor.[7][2] The drive in Dave Jones's machine carries the labels CMECF0010CE01 and K-61433-01.[16]

Memory backup cell

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A rechargeable GS GB50H-3 nickel-cadmium cell (3.6 V, 50 mAh) on the main board keeps the contents of the 16 KB SRAM, which holds the memory switch settings, while the machine is unplugged.[2][1][4] Poe photographed one that had leaked onto the board.[2]

Specifications

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X68000 (CZ-600C) specifications (owner's manual and IPSJ Computer Museum)
Item Specification
CPU Hitachi HD68HC000, 10 MHz
Sub-CPU OKI MSM80C51, for keyboard scanning and television control
ROM 128 KB IPL and BIOS (the IPSJ Computer Museum gives 256 KB); 768 KB character generator
Main memory 1 MB, expandable to 12 MB
Video memory 512 KB text, 512 KB graphics, 32 KB sprite
Backed-up memory 16 KB SRAM
Display modes 768 × 512, 512 × 512, 512 × 256, 256 × 256
Colours 65,536 per dot in 512 × 512 mode
Sprites 128 patterns of 16 × 16 dots; 128 per screen, 32 per line
Sound Yamaha YM2151 eight-channel FM; OKI MSM6258 ADPCM
Floppy drives Two 5.25-inch 2HD, 1 MB each
Hard disk Optional external SASI drive (CZ-500H, CZ-501H, 10 MB)
Expansion Two I/O slots
Power 100 V AC, 50/60 Hz; 44 W, 10 W or less on standby
Size and weight Main unit 155 × 363 × 270 mm, 7.7 kg; keyboard 463 × 33 × 196 mm, 1.5 kg
Operating system Human68k

[3][1]

Known faults

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  • Leaking electrolytic capacitors in the power supply, on the boards and in the floppy drives. See Sharp X68000 Capacitor Replacement Guide.
  • A leaking backup cell on the main board. On later-lot boards the electrolyte can corrode the crystal oscillator, and the machine then lights its power lamp but shows no picture.[2]
  • Floppy drives with leaking capacitors and dried-out grease.[2][7]
  • Corroded contacts in the floppy drive cable connectors.[2]

These are covered in the Sharp X68000 Troubleshooting Guide.

Documentation

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Sharp has republished the service manual for the Sharp X68000 XVI free of charge through its COCORO BOOKS e-book store, but not one for the CZ-600C.[17] Poe's capacitor lists and the Dave Jones teardown photographs are the most detailed public records of this model's boards.

Repair guides

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  • Drive tower with the UADP-0047CEZZ power supply (Dave Jones, CC BY 2.0)
    Drive tower with the UADP-0047CEZZ power supply (Dave Jones, CC BY 2.0)
  • Sound section of the main board K5023DE (Dave Jones, CC BY 2.0)
    Sound section of the main board K5023DE (Dave Jones, CC BY 2.0)
  • Video board K5024DE (Dave Jones, CC BY 2.0)
    Video board K5024DE (Dave Jones, CC BY 2.0)
  • Floppy drive with its Seiko Epson stepping motor (Dave Jones, CC BY 2.0)
    Floppy drive with its Seiko Epson stepping motor (Dave Jones, CC BY 2.0)
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References

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  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 X68000, IPSJ Computer Museum, Information Processing Society of Japan—link(accessed 2026-10-21) Announced 1986, first sold March 1987; MC68000-family CPU, 1 MB RAM as standard; X68000 specification table: HD68HC000 at 10 MHz, MSM80C51 sub-CPU for keyboard scanning, 256 KB IPL/BIOS ROM and 768 KB character generator ROM, 1 MB main memory expandable to 12 MB, 512 KB text VRAM, 512 KB graphic VRAM, 32 KB sprite VRAM, 16 KB SRAM, display modes 768×512, 512×512, 512×256 and 256×256, 65,536 colours in 512×512 mode, 128 sprites of 16×16 dots, YM2151 eight-channel FM and MSM6258 ADPCM, two 5-inch 2HD (1 MB) drives, optional CZ-500H and CZ-501H 10 MB hard disks, Human68k; came with Gradius; series table with first sale dates and model numbers for every X68000 and X68030 model.
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 SHARP X68000 修理– Poe—link(accessed 2026-10-21) Repair notes for a CZ-600C: model table (CZ-600C, March 1987, ¥369,000, black added November 1987); board numbers K5023DE (main board, same on early and late lots), K5026DE (expansion slots), K5027DE (interface board), K5028DE to K5030DE (LED boards); 1 MB RAM board CZ-6BE1; GS Ni-Cd GB50H-3 3.6 V 50 mAh SRAM battery; early-lot boards with RH-IX0898CEZZ and RH-IX0897CEZZ and an upright crystal oscillator, later lots with IX0898CE and IX0897CE and the oscillator lying flat; power supply type table (CZ-600C supply used only by the first model); FDD unit K-61432-71 with Seiko Epson SST-20C120L stepping motor; keyboard DSETK0016CE01 (grey) and DSETK0016CE02 (black) with Alps green switches; full electrolytic capacitor lists.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Sharp, X68000 取扱説明書 (owner's manual, File:Sharp X68000 CZ-600C Owner's Manual.pdf), B.2 specifications, printed pages 179 and 180 (PDF pages 193 and 194): 68000 at 10 MHz and 80C51 for keyboard scanning and television control; ROM 128 KB (IPL, BIOS) and 768 KB (character generator); main memory 1 MB, up to 12 MB; 128 sprites per screen, 32 per line; two 1 MB 5-inch drives with auto-load and auto-eject; two I/O slots; 100 V AC 50/60 Hz, 44 W (10 W or less on standby); main unit 155 × 363 × 270 mm, 7.7 kg. Described at Sharp X68000 CZ-600C Owner's Manual.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 X68000, Wikipedia (Japanese)—link(accessed 2026-10-21) History and model list: black CZ-600C added November 1987; the twin-tower case (called the "Manhattan shape") with two auto-eject 5.25-inch 2HD drives and the power supply in one tower and the main board and two expansion slots in the other; main power switch on the rear of the tower models; specification sheet giving 100 V AC 50/60 Hz.
  5. ↑ 5.0 5.1 X68000シリーズ電源のハンダ面から見た抵抗配置図– Kunihiko Ohnaka (kunichiko), 2020-10-10—link(accessed 2026-10-21) Power supply by model, quoted from Poe's site: CZ-600C own unit; ACE SH2; ACE-HD SH3; EXPERT, EXPERT II, SUPER, XVI and X68030 SH4; PRO "PRO-BOX"; PRO II SH5; Compact and X68030 Compact SH7. Measured in-circuit resistances for SH4 and SH5 boards; SH4 schematic in the XVI and X68030 service manuals; SH5 repair in which Q31 and Q32 had failed short and the fuse had blown.
  6. ↑ X68000 ACE/ACE-HD CZ-601C CZ-611C / FDDユニット K61432-72 / 電源 SH2･SH3 修理– Poe, 2021-01-20—link(accessed 2026-10-21) ACE board numbers: main board K5709DE, control board (base) K5710DE with the Ni-Cd cell, analogue board K5711DE.
  7. ↑ 7.0 7.1 7.2 SHARP X68000 FDD K61432-71 K61432-72 K-61435-72 修理– Poe, 2020-02-23—link(accessed 2026-10-21) Four broad versions of X68000 drive: K-61432-71 for the CZ-600C only, K-61432-72 (later K-61435-72) for the ACE to X68030, one for the PRO and PRO II, and the 3.5-inch drive of the Compact models; capacitor lists for K-61432-71 version 09 and versions 03, 04 and 07; electrolytics under the spindle motor and on the motor driver board found leaking; Hitachi HA13431 spindle motor driver; E-ring fitting; head adjustment depends on the index sensor timing, so the spindle and stepping motors should not be removed just to change capacitors.
  8. ↑ 8.0 8.1 8.2 Sharp X68000 Personal Computer Teardown (17265064954)– Dave Jones, Wikimedia Commons—link(accessed 2026-10-21) Photograph: front of a black CZ-600C (HIGH RESO., TIMER and POWER lamps, drive slots 0 and 1, PHONES, JOY STICK 1, VOLUME, KEY BOARD and MOUSE sockets) with the main board marked K5023DE and the board marked K5024DE beside it.
  9. ↑ Sharp X68000 Personal Computer Teardown (17884657232)– Dave Jones, Wikimedia Commons—link(accessed 2026-10-21) Photograph of the main board's sound and video output section: IC41 ET (IX0904CE), IC42 BUDDHA, IC16 Mitsubishi M51387P, electrolytics C2, C3, C18, C21, C22, C26, C28 and C36, trimmers VR1 to VR3.
  10. ↑ Sharp X68000 Personal Computer Teardown (17699842898)– Dave Jones, Wikimedia Commons—link(accessed 2026-10-21) Photograph of board K5024DE: MB81461-12 video RAM in IC1 to IC32, IC41 VINAS1 (IX0902CE), IC42 VINAS2 (IX0903CE), IC50 VSOP, IC37 RESERVE (IX0907CE), electrolytic C45.
  11. ↑ Sharp X68000 Personal Computer Teardown (17861279076)– Dave Jones, Wikimedia Commons—link(accessed 2026-10-21) Close-up of IC67 CYNTHIA and IC63 CYNTHIA JR (IX0908CE) on the main board.
  12. ↑ Sharp X68000 Personal Computer Teardown (17887580335)– Dave Jones, Wikimedia Commons—link(accessed 2026-10-21) Photograph of the processor sub-board: Hitachi HD68HC000PS10 CPU and HD63450PS10 DMA controller, with the BUDDHA chip on the main board beside it.
  13. ↑ Sharp X68000 Personal Computer Teardown (17267174853)– Dave Jones, Wikimedia Commons—link(accessed 2026-10-21) Photograph of the inside of the drive tower of a CZ-600C: floppy drive and the metal-cased power supply labelled UADP-0047CEZZ (ZSSE640J).
  14. ↑ 14.0 14.1 Sharp, X68000 取扱説明書 (File:Sharp X68000 CZ-600C Owner's Manual.pdf), 3.2, rear of the computer, printed pages 12 and 13 (PDF pages 26 and 27): I/O slot covers, REMOTE (with the main switch on, a signal here can switch the computer on even with the front switch off), PRINTER, frame earth, STEREOSCOPIC, TV CONTROL, SEE THROUGH COLOR, IMAGE IN, ANALOG RGB OUT, RS-232C, audio in and out, JOY STICK 2, main POWER switch, 100 V inlet, switched AC 100 V outlet (300 W maximum), EXPANSION FDD, HARD DISK and DISK EJECT.
  15. ↑ Sharp, X68000 取扱説明書 (File:Sharp X68000 CZ-600C Owner's Manual.pdf), 6.3, printed page 42 (PDF page 56): if a foreign object or a program crash stops a disc ejecting, use the DISK EJECT button on the rear, which forces the disc out regardless of the drive's state and can corrupt the disc if used during normal operation; do not block the disc as it ejects; put nothing but discs and the protective sheet in the drives; thick or lifting labels can stop a disc ejecting.
  16. ↑ Sharp X68000 Personal Computer Teardown (17884614772)– Dave Jones, Wikimedia Commons—link(accessed 2026-10-21) Photograph of a CZ-600C floppy drive in the tower: Seiko Epson SST-20C120L stepping motor (M2057, 12 V 0.69 A), drive labels CMECF0010CE01 and K-61433-01, electrolytics on the drive board.
  17. ↑ 復刻サービスマニュアルX68000, Sharp, COCORO BOOKS—link(accessed 2026-10-21) The series holds one title, the service manual for the X68000 CZ-634C/CZ-644C (XVI), priced at ¥0; Sharp notes it is published to preserve the historical record of its past products.


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