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Sharp MZ-80B

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Sharp MZ-80B
Sharp MZ-80B
An MZ-80B at the Osaka City Science Museum (photo: Darklanlan, CC BY 4.0)
Specifications
ManufacturerSharp Corporation
TypePersonal computer
Released1981 (Japan)[1]
Intro price¥278,000[1]
CPUSharp LH0080A (Z80A) at 4 MHz[2]
Memory64 KB in Sharp's service manual; 32 KB on export machines according to other sources[2][1][3]
StorageBuilt-in cassette deck under software control[2]
DisplayBuilt-in 9-inch green CRT, 40 × 25 or 80 × 25 characters; 320 × 200 graphics with an option[2][1]
Sound400 mW speaker[2]
ROM2 KB IPL ROM, 2 KB character generator ROM[2]
Power240 V AC 50 Hz (European model in the service manual); 100 V in Japan[2][1]
Dimensions450 × 270 × 520 mm (W × H × D)[2]
WeightAbout 16 kg[2]
OS / Firmware—
PredecessorSharp MZ-80K
Model no.MZ-80B

The Sharp MZ-80B is a personal computer that Sharp Corporation released in 1981, with a 4 MHz Z80A processor, a 9-inch green monitor, a full keyboard with numeric pad and function keys, and a cassette deck in one case.[1][2] Sharp's service manual calls it a stepped-up version of the Sharp MZ-80K, but the two are not compatible.[4][1] Apart from the character generator, its only ROM is a 2 KB IPL, which loads the monitor and the language from tape or disk into RAM.[1][2]

History

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Sharp sold the MZ-80B in Japan from 1981 at 278,000 yen. It was followed in 1982 by the MZ-80B2, which had one plane of graphics RAM fitted as standard and a changed power supply, and by the MZ-2000, which runs MZ-80B programs at the BASIC level.[1] Japanese Wikipedia records that export machines had 32 KB of RAM as standard, with the rest an option, and a character generator with reversed letters in place of the katakana.[1]

Hardware

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MZ-80B units (service manual)
Unit Main parts
CPU board LH0080A (Z80A), LH0081A PIO (IC24) for the keyboard, 8255 (IC23) for the cassette deck and sound, 8253 (IC19) for the clock, 2 KB IPL ROM, 2 KB character generator, 16K dynamic RAMs, 2 KB video RAM, 16 MHz crystal
Power supply (DBOXD0028PAZZ) SG3524N switching regulators for +12 V (IC301) and +5 V (IC401), FS7905 regulator for −5 V (IC201), and an unregulated 12 V output
Monitor (DPWB-0221PAZZ) E2728B31 9-inch tube, µPC1031H vertical deflection (IC2001), LA4200 sound amplifier (IC2002)
Cassette recorder Reel motor, capstan motor, brake and panel solenoids, relays RY1 to RY3

[2][5][6][7]

The sources disagree on the standard memory. Sharp's service manual gives 64 KB in 32 16K chips. SharpMZ.net's technical data gives 32 KB, expandable to 64 KB, and Japanese Wikipedia says export machines had 32 KB.[2][3][1] A machine restored by Retro.Engineer had a memory expansion board fitted.[8]

The cassette deck is under software control. The service manual's specifications give 1,800 bit/s, while Japanese Wikipedia gives 2,000 baud.[2][1] The rear panel has the IPL reset switch, brightness and volume controls, the mains inlet and switch, a ground terminal and six access windows for I/O modules.[9] Options fitted inside include the MZ-80EU expansion port, which takes up to six interface cards, the MZ-80IO2 universal I/O card, the MZ-80GMK expansion graphic RAM and the MZ-80FI floppy disk interface for the MZ-80FB and MZ-80FBK drives.[2][9]

Known faults

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  • The two 0.047 µF 250 V mains filter capacitors C101 and C102 on the power supply's primary board. On the machine Retro.Engineer restored, one exploded about ten seconds after the first power-on; both were replaced.[8][6]
  • Vertical collapse, a single horizontal line on the screen. Retro.Engineer traced it to C2010, a 1 µF 35 V tantalum on the monitor board, which had shorted. Sharp's fault chart names C2010 among the parts to check when the raster is too narrow.[8][10]
  • A perished cassette drive belt.[8]

See Sharp MZ-80B Troubleshooting Guide and Sharp MZ-80B Capacitor Replacement Guide.

Documentation

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  • Sharp MZ-80B Service Manual: Sharp's English service manual, with fault charts, circuit diagrams and the parts list for the machine and its options.
  • SharpMZ.net hosts the MZ-80B owner's manuals, the SB-1510 monitor reference manual and BASIC manuals.[11]

Repair guides

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  • MZ-80B (Darklanlan, CC BY 4.0)
    MZ-80B (Darklanlan, CC BY 4.0)
  • Power supply boards from the service manual
    Power supply boards from the service manual
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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 MZ-80, Wikipedia (Japanese)—link(accessed 2026-10-21) MZ-80B: released 1981, 64 KB all-RAM design, 278,000 yen; Z80A at 4 MHz; only an IPL in ROM, the monitor loaded into RAM; text in 40 or 80 columns; optional graphics of 320 × 200 in up to two planes (MZ-8BG, MZ-8BGK); green monitor; cassette deck under software control (fast forward, rewind, eject, search) at 2,000 baud; Japanese model 100 V, 65 W, 450 × 520 × 270 mm, about 16 kg; sold abroad with 32 KB as standard; MZ-80B2 (1982) with one plane of graphics RAM fitted and a changed power supply; successor MZ-2000 compatible at BASIC level.
  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 Corporation, Service Manual, Personal Computer MZ-80B (File:Sharp MZ-80B Service Manual.pdf), specifications, printed pages 1 and 2 (PDF pages 3 and 4): LH0080A (Z80A) at 4 MHz; ROM 2 KB; RAM 64 KB (dynamic), 32 16K RAM chips; video RAM 2 KB; character generator 2 KB; LH0081A (Z80A PIO), 8253 and 8255; 9-inch green CRT, 40 × 25 or 80 × 25 characters by software; cassette at 1,800 bit/s, Sharp PWM, manual or automatic control, 4.75 cm/s, C30 to C60 tapes; sound 400 mW at 440 Hz; 92 keys with ten numeric keys, function keys, cursor keys and tape deck keys; AC 240 V 50 Hz; power supply outputs 5 V, −5 V, 12 V regulated and 12 V unregulated; display E2728B31 9-inch tube, 12 V 1.1 A, 11.0 kV; width 45 cm, depth 52 cm, height 27 cm; about 16 kg. Hosted with a description at Sharp MZ-80B Service Manual.
  3. ↑ 3.0 3.1 Technical data of the MZ-80B, SharpMZ.net—link(accessed 2026-10-21) RAM 32 KB, expandable to 64 KB as an option; IPL ROM 2 KB; 9-inch green CRT; cassette at 1,800 bit/s; AC 220 V 50 Hz, about 45 W; about 16 kg.
  4. ↑ Sharp, MZ-80B service manual (File:Sharp MZ-80B Service Manual.pdf), cover: "The MZ-80B, stepped up version of the MZ-80K, is a personal computer with many new functions"; Z-80 (4 MHz version); ten numeric keys and ten function keys; cassette recorder with an electromagnetic mechanism that can be stopped and started remotely; I/O cards fitted inside with the optional expansion port.
  5. ↑ Sharp, MZ-80B service manual (File:Sharp MZ-80B Service Manual.pdf), CPU board section, printed page 8 (PDF page 10): cassette and audio blocks, check IC23 (8255); keyboard block, check IC24 (LH0081A); clock block, check IC19 (8253); RAM checked with the RAM checker.
  6. ↑ 6.0 6.1 Sharp, MZ-80B service manual (File:Sharp MZ-80B Service Manual.pdf), replacement parts list: CPU board crystal 16 MHz (PDF page 72); monitor TV board DPWB-0221PAZZ, IC2001 µPC1031H, IC2002 LA4200 (PDF page 72); cassette relays RY1 and RY3 (G2V) and RY2 (G2E) (PDF page 75); power supply unit DBOXD0028PAZZ, IC201 FS7905, IC301 and IC401 SG3524N, Q301 and Q401 2SA770, Q302 and Q402 2SA673C, fuses F101 and F102 T630 mA, F201 T1 A, F301 T1.6 A, F401 and F402 T3.15 A, C101 and C102 0.047 µF 250 V (PDF page 76).
  7. ↑ Sharp, MZ-80B service manual (File:Sharp MZ-80B Service Manual.pdf), block diagram of the cassette tape recorder, printed page 24 (PDF page 26): reel motor, capstan motor, brake solenoid, panel solenoid, relays RY2 and RY3, Hall IC tape rotation detection, micro-switch cassette detection.
  8. ↑ 8.0 8.1 8.2 8.3 Sharp MZ-80B, Retro.Engineer, 2024-11-22—link(accessed 2026-10-21) The back opens like a car bonnet, showing the power supply, logic board and expansion cage; a memory expansion board on the logic board; CRT driver board and a combined tape controller and audio amplifier board in the top housing; supply rails checked with the logic board disconnected; a RIFA capacitor missed on inspection exploded about ten seconds after first power-on, and both RIFAs were replaced; belt replaced; vertical collapse traced from test point 7 to C2010, which was short-circuited; BASIC SB-5510 written to tape from an MZF file with mzf2wave; floppy controller with a DB-37 connector following the Shugart interface.
  9. ↑ 9.0 9.1 Sharp, MZ-80B service manual (File:Sharp MZ-80B Service Manual.pdf), "Fig. 3 Rear View of MZ-80B", printed page 4 (PDF page 6); system configuration, printed page 3: up to six interface cards in the expansion port.
  10. ↑ Sharp, MZ-80B service manual (File:Sharp MZ-80B Service Manual.pdf), monitor TV trouble shooting chart, printed page 21 (PDF page 23): raster too narrow, if the vertical oscillator waveform at pin 4 of IC2001 is wrong check the V-HOLD control, C2010 and R2014.
  11. ↑ MZ-80B downloads, SharpMZ.net—link(accessed 2026-10-21)


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