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║   ZX-PORTSCANNER V1.0                                            ║
║   Sinclair ZX Spectrum I/O Port Scanner & Analyzer               ║
║   github.com/bad-antics | NullSec Retro Series                   ║
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Overview

ZX-PORTSCANNER is a BASIC utility for the Sinclair ZX Spectrum that scans and displays the state of I/O ports. Essential for hardware debugging, peripheral detection, and understanding the Spectrum's architecture.

Features

• Port Map Display: Shows all documented ZX Spectrum I/O ports
• Keyboard Matrix Scan: Reads all 8 keyboard half-rows
• Full Port Scan: Scans all 256 base ports for active devices
• Binary Display: Shows port values in binary for bit analysis
• Colored Output: Uses INK colors for better readability

ZX Spectrum I/O Map

Port	Function
$FE	ULA (Keyboard/Tape/Speaker/Border)
$FF	Floating Bus
$7FFD	128K Memory Paging
$BFFD	AY-3-8912 Data Register
$FFFD	AY-3-8912 Address/Register
$1FFD	+3 Disk/Printer

Usage

1. Load the program: LOAD ""
2. Run: RUN
3. View the port map and keyboard scan
4. Press any key for full 256-port scan

Keyboard Matrix

The Spectrum keyboard is organized as an 8×5 matrix:

Row	Keys	Port
0	CAPS-V	$FEFE
1	A-G	$FDFE
2	Q-T	$FBFE
3	1-5	$F7FE
4	0-6	$EFFE
5	P-Y	$DFFE
6	ENTER-H	$BFFE
7	SPACE-B	$7FFE

Compatibility

• ZX Spectrum 16K/48K
• ZX Spectrum 128K
• ZX Spectrum +2/+2A
• ZX Spectrum +3
• Fuse/ZXSpin/Spectaculator emulators

Loading

From Tape

LOAD ""
RUN

From +3 Disk

LOAD "scanner.bas"
RUN

Technical Notes

• Uses Spectrum BASIC IN function for port reading
• Port values of $FF typically indicate no device
• Keyboard ports return $FF when no key pressed (active low)
• 128K ports only respond on 128K models

Part of the NullSec Retro Series

Single-script security and system tools for vintage computing platforms.

License

MIT License - See LICENSE file