Sharp X68000 XVI
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| An X68000 XVI, model CZ-634C, with the 16MHz, 10MHz, TIMER and HD BUSY lamps on the right-hand tower (photo: htomari, CC BY-SA 2.0) | |
| Specifications | |
|---|---|
| Manufacturer | Sharp |
| Type | Personal computer |
| Released | May 1991[1] |
| Intro price | ¥368,000 (XVI); ¥518,000 (XVI-HD)[2] |
| CPU | MC68HC000 at 16.67 MHz, switchable to 10 MHz[3][2] |
| Memory | 2 MB, expandable to 12 MB[3] |
| Storage | Two 5.25-inch 2HD floppy drives; 80 MB 3.5-inch SCSI hard disk in the XVI-HD[3] |
| Display | Up to 768 × 512; 65,536 colours at 512 × 512[3] |
| Sound | Yamaha YM2151 FM, OKI MSM6258 ADPCM[3] |
| Power | 100 V AC, 50/60 Hz[3][4] |
| Dimensions | 155 × 364 × 270 mm (main unit)[4] |
| Weight | 8.1 kg (CZ-634C), 8.8 kg (CZ-644C)[4] |
| OS / Firmware | — |
| Successor | Sharp X68030 |
| Model no. | CZ-634C-TN (XVI), CZ-644C-TN (XVI-HD) |
The Sharp X68000 XVI (models CZ-634C and CZ-644C) is the 16 MHz version of the Sharp X68000, sold in Japan from May 1991.[1][2] It keeps the twin-tower case of the earlier models, with the clock switchable between 16 and 10 MHz, 2 MB of memory as standard and a SCSI port; the XVI-HD adds an 80 MB hard disk.[3][2]
The XVI uses the power supply that owners call the SH4, board UADP-0069CEZZ, which is also fitted to the Sharp X68000 EXPERT, EXPERT II, Sharp X68000 SUPER and Sharp X68030.[5][6] Sharp's service manual for the XVI has the circuit diagrams of that supply and of the main, control, analogue, I/O and keyboard boards with every component value.[7][6] Sharp now gives that manual away as a free e-book; it is the only X68000 service manual in Sharp's reissued series.[8] The faults that owners write up are leaking electrolytic capacitors in that supply, a flat backup battery and floppy drive faults.[9][10]
History
[edit | edit source]Sharp put the XVI and XVI-HD on sale in May 1991 at ¥368,000 and ¥518,000.[1][2] They came only in titanium black (model suffix -TN), like the SUPER before them, and the case was reshaped. The XVI-HD set won a Good Design Award in 1991.[2] The Sharp X68000 Compact of February 1992 used the same 16 MHz design in a smaller case with 3.5-inch drives, and the Sharp X68030 replaced the twin-tower machines in March 1993.[1][2]
Hardware
[edit | edit source]Boards
[edit | edit source]Poe, a Japanese repairer, lists the XVI's boards, which are the same in the XVI and XVI-HD: main board K7243DE, control board K7244DE in the base, analogue board K7245DE, expansion slot board K7246DE, interface boards K7247DE and K7248DE in the left-hand tower, and the lamp boards K7249DE to K7251DE.[11] The service manual's circuit diagrams carry the same numbers (DUNTK7243DE01 for the main board, DUNTK7244DE01 for the control board and DUNTK7245DE01 for the analogue board).[7]
Processor and memory
[edit | edit source]The MC68HC000 runs at 16.67 MHz, and the clock can be switched to 10 MHz; the power lamp board carries a lamp for each speed, labelled 16MHz and 10MHz on the right-hand tower.[3][2][7][12] The main board has a socket for an MC68881 floating-point coprocessor.[7][2] Memory beyond the standard 2 MB goes first on an internal connector, which takes up to 6 MB more in 2 MB steps; the expansion slots then take the total to 12 MB.[3] The internal connector exists because the slots run at 10 MHz.[2]
Power supply
[edit | edit source]The supply sits in the left-hand tower seen from the front.[9] It runs from 100 V mains only, through a 125 V 4 A fuse, and produces +5 V for the main board, +5 V, +12 V and −12 V for the control board, +5 V and +12 V for the floppy drives and the hard disk, and a separate +5 V standby rail (VCC2) from a small second converter.[6] The rear panel has the main POWER switch, the mains inlet and a switched AC outlet marked MAX 300W.[6][13] As on the other tower models there is a main switch on the rear as well as the front switch, and software can switch the machine on and off.[2] Sharp's manual says to switch on at the rear and then the front, and to switch off at the front and wait for the 16MHz or 10MHz lamp to turn red before switching off at the rear; that lamp is red when only the rear switch is on and green when the machine is running. The service outlet is live whenever the mains plug is in, whatever the switches are set to.[14]
Backup battery
[edit | edit source]The 16 KB SRAM holds the memory switch settings.[3][2] It is backed up by a 3.0 V battery on the control board in the base.[7][9] Fram found the battery in his XVI-HD completely flat.[9]
Drives
[edit | edit source]The two 5.25-inch drives eject discs automatically, and each slot has an EJECT button beneath it.[2][12] Poe reports that version 07 of the drive unit is found in late machines such as the XVI, though not in all of them, and has repaired a version 06 drive from an XVI.[10] The XVI-HD has an 80 MB 3.5-inch hard disk on the internal SCSI bus, and the rear SCSI connector takes external drives.[3][13]
Specifications
[edit | edit source]| Item | Specification |
|---|---|
| CPU | MC68HC000, 16.67 MHz (switchable to 10 MHz) |
| Floating-point unit | MC68881, optional, in a socket on the main board |
| Sub-CPU | MSM80C51 in the keyboard |
| ROM | 1 MB character generator ROM, including the IPL and BIOS |
| Main memory | 2 MB; 6 MB more on the internal connector; 12 MB maximum |
| Video memory | 512 KB text, 512 KB graphics, 32 KB sprite |
| SRAM | 16 KB, battery-backed |
| Display | Up to 768 × 512; 512 × 512 with 65,536 colours; 31.5 kHz and 15.98 kHz modes |
| Sprites | 16 × 16 dots, 128 patterns; 128 per screen, 32 per line |
| Sound | YM2151 FM (8 channels); MSM6258 ADPCM |
| Drives | Two 5.25-inch 2HD; 80 MB 3.5-inch hard disk in the CZ-644C |
| Interfaces | Expansion floppy, SCSI, keyboard, analogue RGB, TV control, RS-232C, mouse, Centronics printer, two joysticks, audio in and out with headphones, image input |
| Expansion | Two I/O slots |
| Power | 100 V AC, 50/60 Hz; 41 W (CZ-634C), 46 W (CZ-644C) |
| Size and weight | 155 × 364 × 270 mm; 8.1 kg (CZ-634C), 8.8 kg (CZ-644C) (owner's manual) |
[3] The owner's manual and the IPSJ Computer Museum give 81 MB for the XVI-HD's hard disk, where the service manual gives 80 MB. The owner's manual also gives lower power figures, 37 W (CZ-634C) and 42 W (CZ-644C), with 99 W maximum and 6 W or less on standby.[4][1][3]
Known problems
[edit | edit source]- Leaking power supply capacitors: the SH4 supply's electrolytics leak. In Fram's XVI-HD the electrolyte ran down onto the base board, shorted parts of the standby circuit round R33 and R34, burst a power transistor and blew the fuse.[9] See the Sharp X68000 XVI Capacitor Replacement Guide.
- A flat backup battery: the settings in SRAM are lost when the 3.0 V battery on the control board is flat.[9][7]
- Floppy drives: the drives have their own electrolytic capacitors, some of which Poe has found leaking.[10]
Repair guides
[edit | edit source]- Sharp X68000 XVI General Maintenance
- Sharp X68000 XVI Troubleshooting Guide
- Sharp X68000 XVI Capacitor Replacement Guide
Documentation
[edit | edit source]- Sharp X68000 XVI Service Manual (CZ-134, April 1991)
- Sharp X68000 XVI Owner's Manual (TINS-4643CEZZ)
Related pages
[edit | edit source]References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 X68000, IPSJ Computer Museum, Information Processing Society of Japan—link(accessed 2026-10-21) Series table: X68000 XVI, CZ-634C, May 1991, 68000 at 16 MHz, 2 MB; X68000 XVI-HD, CZ-644C, 2 MB, 81 MB hard disk, SCSI; X68030 (CZ-500C) followed in March 1993. Twenty X68000-series models were sold up to 1993.
- ↑ 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 X68000, Wikipedia (Japanese)—link(accessed 2026-10-21) Model table: X68000 XVI CZ-634C and XVI-HD CZ-644C, May 1991, ¥368,000 and ¥518,000, colour code -TN, tower case, 2 MB; 16 MHz mode added and body shape changed; CZ-644C-TN set won a 1991 Good Design Award. The XVI and Compact XVI use a Motorola MC68000 with the clock selectable between 16 and 10 MHz, and a dedicated socket for the floating-point unit on the main board. Main memory can be added inside the machine up to 8 MB, because the expansion slots run at 10 MHz. From the SUPER onwards the only colour is titanium black. The tower models have a rear main power switch and can be switched on and off by software.
- ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 Sharp, service manual CZ-134 for the CZ-634C-TN and CZ-644C-TN (File:Sharp X68000 XVI Service Manual.pdf), 1-2 specifications, printed pages 4 to 7 (PDF pages 4 to 7): MPU MC68HC000 (16.67 MHz); keyboard sub-CPU MSM80C51; DMAC HD63450; optional FPU MC68881 (16.67 MHz); MFP MC68901; CRTC IX1093 (VICON); sprite controller IX0906 (CYNTHIA); FDC µPD72065; video controller IX1095 (VIPS); SCSI controller MB89352; SCC Z8530; RTC RP5C15; FM sound YM2151; ADPCM MSM6258; PPI µPD8255. CG ROM 1 MB including the IPL and BIOS. Main memory 2 MB, 6 MB more on the internal connector in 2 MB units, up to 12 MB; text VRAM 512 KB; graphic VRAM 512 KB; sprite VRAM 32 KB; SRAM 16 KB. Two internal 5-inch 2HD drives; internal 3.5-inch 80 MB hard disk (optional for the CZ-634C). Two expansion I/O slots. 100 V AC, 50/60 Hz; 46 W (CZ-644C), 41 W (CZ-634C). Sprites: 16 × 16 dots, 128 patterns, 128 per screen and 32 per line. Described at Sharp X68000 XVI Service Manual.
- ↑ 4.0 4.1 4.2 4.3 Sharp, X68000 XVI・XVI HD 取扱説明書 (owner's manual, File:Sharp X68000 XVI Owner's Manual.pdf), B.2 specifications, printed pages 127 and 128 (PDF pages 143 and 144): 68000 at 16 or 10 MHz; 80C51 for keyboard scanning and TV control; IPL and BIOS ROM 128 KB, character generator 768 KB; 2 MB main memory up to 12 MB; FM sound 2 channels, 8 octaves, 8 voices, ADPCM; 81 MB 3.5-inch hard disk in the CZ-644C, optional in the CZ-634C; two 1.2 MB 5.25-inch drives with auto-load and auto-eject; sockets for additional RAM and a floating-point coprocessor; two I/O slots (10 MHz); CZ-634C 37 W rated, CZ-644C 42 W rated, both 99 W maximum and 6 W or less on standby; 100 V AC 50/60 Hz; 10 to 35 °C; main unit 155 × 364 × 270 mm, 8.1 kg (CZ-634C) or 8.8 kg (CZ-644C). Described at Sharp X68000 XVI Owner's Manual.
- ↑ 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. The SH4 schematic is in the XVI and X68030 service manuals.
- ↑ 6.0 6.1 6.2 6.3 Sharp, service manual CZ-134 (File:Sharp X68000 XVI Service Manual.pdf), 22, power supply basic wiring diagram, printed pages 97 and 98 (PDF page 85): board UADP-0069CEZZ; AC 100 V inlet (125 V 7 A) and switched outlet (125 V 15 A, 300 W maximum) through the power switch; fuse F1 125 V 4 A; bridge DB1 (RBV404M); reservoir C9 470 µF 180 V; switching transistor Q1 (2SK643, 2SK724 or 2SK735); transformer T1 (K01717AA001); +12 V regulator IC22 (SI3122V); −12 V regulator IC23 (µPC78M12HF); +5 V from rectifier D27 (FMB-33S or FMB-34S) and choke L21; standby converter T2 (K01716AA002) with Q31 (2SC2333) and IC31 (µPC78M05HF) for the +5 V VCC2 rail; fan MMF06B12DM on +12 V. Connector A (control board): A1 +5 V, A2 GND, A3 +12 V, A4 −12 V, A5 +5 V (VCC2), A6 P.C; connector B (main board): B1 +5 V, B2 GND; P and Q (floppy drives): +12 V, GND, +5 V; D (hard disk): D1 +5 V, D2 GND, D3 +12 V. A crop is at File:Sharp X68000 XVI power supply schematic (service manual).png.
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 Sharp, service manual CZ-134 (File:Sharp X68000 XVI Service Manual.pdf): main board diagrams (1) to (5), printed pages 75 to 84 (PDF pages 73 to 77), board DUNTK7243DE01 with the MPU (IC22, MC68HC000-16), the FPU socket (IC13, MC68881-16) and the video output stage; control board diagram, printed pages 85 and 86 (PDF page 78), board DUNTK7244DE01 with the MFP, SCC, FDC, ADPCM, FM sound, the RP5C15 clock (IC208) with its 32.768 kHz crystal, and a 3.0 V backup battery; I/O and connector diagrams, printed pages 89 and 90 (PDF page 80); analogue board diagram, printed pages 93 and 94 (PDF page 83), board DUNTK7245DE01 with the RGB output stage and connector; keyboard diagram, printed pages 101 and 102 (PDF page 87), with an 80C51 keyboard controller. The power lamp board DUNTK7249DE01 carries the 16M MODE and 10M MODE lamps, the HD BUSY and TIMER lamps and the 16/10 MHz switch.
- ↑ 復刻サービスマニュアルX68000, Sharp, COCORO BOOKS—link(accessed 2026-10-21) Series page listing one title, サービスマニュアル X68000 CZ-634C/CZ-644C, price ¥0. The title page gives the e-book release as 13 January 2015 and the printed edition as April 1991.
- ↑ 9.0 9.1 9.2 9.3 9.4 9.5 X68kXVI HDの電源リペア– Fram, 2015-05-23—link(accessed 2026-10-21) An XVI-HD sold as not powering on. The power supply is in the left-hand tower seen from the front. Capacitors marked "Long Life" had leaked; electrolyte ran onto the back of the supply board, onto the supply case and down the cable to the base board. The conductive electrolyte had shorted the zener diode, R33, R34 and a transistor, a power transistor below them had burst and the fuse had blown. After washing the board and replacing all the capacitors and the burnt parts the supply worked; the supply switches its outputs on when its own main switch is on, so it can be tested on the bench. The backup battery was completely flat; he replaced it with a CR2032 in a holder so that it can be changed without dismantling the base board, then initialised the SRAM and set up the machine again with SWITCH.X. The machine had Sharp's 2 MB memory board fitted.
- ↑ 10.0 10.1 10.2 SHARP X68000 FDD K61432-71 K61432-72 K-61435-72 修理– Poe, 2020-02-23—link(accessed 2026-10-21) The drive used from the ACE to the X68030 exists in several versions; version 07 is fitted to late machines such as the XVI and X68030, though not to all of them, and Poe lists the wheel-board capacitors of a version 06 drive from an XVI. Capacitor lists for versions 03, 04 and 07; electrolytics under the spindle motor and on the motor driver board found leaking; the spindle and stepping motors should not be removed just to change capacitors.
- ↑ SHARP X68000 XVI CZ-634C/X68000 XVI-HD CZ-644C SH4 修理 備忘録– Poe—link(accessed 2026-10-21) Boards common to the XVI and XVI-HD: main board K7243DE; control board (base) K7244DE; analogue board K7245DE; expansion slots K7246DE; right-tower lamp (POWER) K7249DE; left-tower lamps K7250DE and K7251DE; left-tower interface boards K7247DE (upper) and K7248DE (lower). The analogue board has eight capacitors and is one of the hardest boards in the XVI to remove them from.
- ↑ 12.0 12.1 Sharp X68000 XVI– htomari, Wikimedia Commons—link(accessed 2026-10-21) Photograph of a CZ-634C-TN: X68000 XVI badge, drive slots 0 and 1 with card inserts and an EJECT button beneath each, 16MHz, 10MHz, TIMER and HD BUSY lamps, PHONES, JOY STICK 1, POWER, VOLUME, KEYBOARD and MOUSE on the base. Hosted here as File:Sharp X68000 XVI CZ-634C front (htomari).jpg.
- ↑ 13.0 13.1 Sharp X68000 XVI back– htomari, Wikimedia Commons—link(accessed 2026-10-21) Photograph of the rear of the same XVI: I/O slots 1 and 2 (with a MIDI card), PRINTER, REMOTE, FG, STEREOSCOPIC, TV CONTROL, SEE THROUGH COLOR, ANALOG RGB OUT, IMAGE IN; ventilation grille, FG, AC100V OUT (MAX 300W), AC100V inlet, POWER switch, EXPANSION FDD and SCSI; RS-232C, AUDIO IN and OUT and JOY STICK 2 on the base. Hosted here as File:Sharp X68000 XVI CZ-634C rear panel (htomari).jpg.
- ↑ Sharp, XVI owner's manual (File:Sharp X68000 XVI Owner's Manual.pdf), 3.1 and 3.2, front and rear of the computer, printed pages 14, 19 and 20 (PDF pages 30, 35 and 36), and 4.3, power, printed page 24 (PDF page 40): the 16MHz and 10MHz lamps double as the power lamp, red with only the rear main switch on and green with the front switch on; the service outlet AC100V OUT (up to 300 W) is live whenever the plug is in, regardless of the switches; switch on rear then front, off front then rear after the lamp has turned red; 10 seconds or more between switching off and on.
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