Check sum error
Sharp Sharp MZ
Severity: ModerateWhat Does This Error Mean?
Check sum error means the data loaded from tape did not match its verification checksum. Some data was corrupted during loading — usually due to a dirty head, worn tape, or signal quality issues. Clean the tape head and try loading again.
Affected Models
- Sharp MZ-80K
- Sharp MZ-80A
- Sharp MZ-80B
- Sharp MZ-700
- Sharp MZ-800
- EmuZ emulator
Common Causes
- Tape head dirty — oxide buildup affecting the signal
- Tape worn or degraded over time
- Electrical interference during loading
- Tape copied at incorrect speed
- Corrupted tape image file (in emulators)
How to Fix It
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Clean the tape head with isopropyl alcohol.
The Sharp MZ's built-in cassette deck collects oxide over time. A clean head dramatically improves loading reliability.
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Rewind and try loading again — checksum errors can be intermittent.
Sometimes a second attempt succeeds. The exact tape position and speed can vary slightly between attempts.
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Try loading at a slightly different speed if your deck has fine speed control.
Some tape decks run slightly fast or slow. A tiny speed difference can cause checksum mismatches.
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On emulators: re-download the tape image file.
The MZF or MZT file may be corrupted. Download a fresh copy from a different source.
Frequently Asked Questions
What is a checksum?
A checksum is a small number calculated from the data and stored at the end of the tape block. When loading, the Sharp MZ recalculates the checksum and compares it to the stored value. If they do not match, the data was corrupted during loading.
Is the Sharp MZ's built-in cassette more reliable than external players?
Generally yes. Sharp tuned the built-in deck to match the exact signal levels the computer expects. External players may have different frequency response curves that cause more loading errors.