Z80 CPU Testing Software - ZX port

for identifying Zilog Z80 CPU variants and clones

ZX Spectrum and clones

• Download: z80typeZX.tap - Program to load

LOAD ""

Documentation

• Technical Details: DOCUMENTATION.md - Specifications
• Z80 ID Guide: Z80ID.md - Z80 CPU Variant Identification Guide

Tested Hardware & Emulators

Real Hardware ✅

System	Model/Issue	CPU Detection	Notes
ZX Spectrum 48K	Issue 3	✅ Working	Hysteresis detection
ZX Spectrum 48K	Issue 4	✅ Working	Hysteresis detection
ZX Spectrum 48K	Issue 5	✅ Working	Hysteresis detection
ZX Spectrum 128K	-	✅ Working	AY chip detection
Pentagon	Clone	✅ Working	Russian clone
TK95	Clone	✅ Working	Brazilian clone
Timex TC 2048	-	✅ Working	Timex control register
Timex TC 2068	-	✅ Working	Timex control register

Emulators ✅

Emulator	Status	Detection Method	Notes
Fuse	✅ Working	Hysteresis and AY	Cross-platform
QtSpecem	✅ Working	Timex control register	Qt-based
ZXSP	✅ Working	Hysteresis	macOS/Windows

CP/M Systems

• Source: Original CP/M version from skiselev/z80-tests

A>ASM Z80TYPE
A>LOAD Z80TYPE
A>Z80TYPE /D    # Run with debug info

What It Does

Identifies your Z80 CPU type with high accuracy:

• NMOS Z80s: Zilog Z80/Z8400, Sharp LH5080A, NEC D780C, NEC D780C-1, KR1858VM1
• CMOS Z80s: Zilog Z84C00, Toshiba TMPZ84C00AP, NEC D70008AC
• U880 Clones: East German MME U880, Thesys Z80

Verify authentic vs remarked CPUs - Detect counterfeit or relabeled chips

Example Output

Z80 Processor Type Detection (C) 2024 Sergey Kiselev
Detected CPU type: Zilog Z84C00

ZX Spectrum: Interactive border color test (press B for black, W for white) or automatic detection methods
CP/M with /D: Shows raw test results and detailed flag analysis for research

Building from Source

ZX Spectrum

zmakebas -a10 -nZ80TEST z80typeZX.bas
pasmo --tap z80typeZX.asm z80typeZX1.tap
cat out.tap z80typeZX1.tap > z80typeZX.tap

Requirements

• ZX Spectrum: Pasmo assembler, zmakebas
• CP/M: ASM.COM, LOAD.COM

Supported Hardware

System	Method	Notes
ZX Spectrum 48K	ULA hysteresis / Visual fallback	Automatic, manual backup
ZX Spectrum 128K/+2/+3	AY chip test	Automatic detection
Timex 2048/2068	Control register	Automatic detection
CP/M Systems	SIO interrupt	RC2014, RCBus modules

How It Works

1. Hardware Detection: Automatically identifies available hardware
2. Detection Method Selection (in priority order):
   • AY chip test → For 128K/+2/+3 models or 48K with AY add-on (highest priority)
   • Timex control register → For TC2048/TC2068 systems
   • ULA hysteresis test → For standard 48K models (automatic)
   • Visual border test → Manual fallback if needed
3. CPU Analysis: Uses undocumented instruction behavior for identification

Different Z80 variants handle undocumented instructions differently, creating unique "fingerprints" for identification.

Usage Notes

• Detection completes automatically - results display immediately
• ZX Spectrum: Program returns to BASIC after showing results and pressing any key
• CP/M: Returns to command prompt, use /D for detailed output

Known Limitations

• Some rare clones may show as "Unknown"
• Results may vary between individual CPU specimens
• Emulator accuracy depends on implementation quality

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Technical Details

Detection Algorithm

Hardware Detection → CMOS/NMOS Test → U880 Bug Test → Flag Pattern Analysis → CPU ID

CPU Signatures

Common CPUs

CPU	CMOS	U880	XF/YF	Notes
Zilog Z80	00h	0	FFh	Standard NMOS
Zilog Z84C00	FFh	0	FFh	Standard CMOS
Sharp LH5080A	00h	0	30h	CMOS-like NMOS

Clone CPUs

CPU	CMOS	U880	XF/YF	Notes
NEC D780C	00h	0	FDh	NMOS clone
NEC D780C-1	00h	0	F0h	NMOS clone
NEC D70008AC	FFh	0	<20h	CMOS clone
Toshiba TMPZ84C00AP	FFh	0	3Fh	CMOS variant
KR1858VM1	00h	0	F4h	Soviet clone

U880 Family

CPU	CMOS	U880	XF/YF	Notes
U880 (new)	varies	1	FFh	Carry bug present
U880 (old)	varies	1	≠FFh	Carry bug + variant flags

Files

• z80typeZX.asm - ZX Spectrum assembly source
• z80typeZX.bas - BASIC loader
• z80typeZX.tap - TAP file
• DOCUMENTATION.md - Technical specs
• Z80ID.md - Z80 CPU Variant Identification Guide
• Results.md - Test results database

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Credits

• Original: Sergey Kiselev (2024) — z80-tests
• ZX Spectrum Port: Rui Ribeiro (2025)
• Spectrum Cassette, EAR and MIC Port behaviour documentation: Pera Putnik (1999)

License

GPL-3.0 License