Aleste520v4

Aleste 520EX — Staggered Mechanical Keyboard Subsystem (keyboard/)

This directory contains the complete KiCad 9.0 schematic, routed 2-layer PCB, 3D switch/stabilizer models, and Bill of Materials for the Aleste 520EX Staggered Mechanical Keyboard (358.0 × 122.0 mm), reverse-engineered directly from the hardware keyboard scan EPROM (rom/RFVDKEY.BIN, IC U65) and system BIOS (rom/AL512.BIN, offset 0x1EEF).

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1. Files in keyboard/

• Aleste520_Keyboard.kicad_pro: KiCad 9.0 project file.
• Aleste520_Keyboard.kicad_sch: Complete electrical schematic (0 ERC errors/warnings) with 82 staggered matrix keys (SW1..SW82), 82 1N4148 anti-ghosting diodes (D1..D82), 1 hardware reset key (SW83), and dual 2x06 (2.54 mm) IDC connectors (J1, J2).
• Aleste520_Keyboard.kicad_pcb: Fully routed 2-layer PCB (358.0 × 122.0 mm, 0 DRC violations, 0 unconnected pads) featuring:
  • Authentic staggered physical key layout with 6.25U (119.06 mm) Spacebar (SW81) and PCB-mount Cherry MX stabilizer holes at ±50.0 mm (Button_Switch_Keyboard:SW_Cherry_MX_6.25u_PCB).
  • Staggered modifier footprints (1.50U TAB, 1.75U CAPS, 2.00U SHIFT, 1.50U RETURN, 1.50U CTRL, 1.25U RUS/LAT, 1.25U COPY, 1.50U GRAPH, and 1.25U top function keys).
  • Separate right-hand Numpad & Cursor block (F0..F9, FDOT, ENTER, UP/DOWN/LEFT/RIGHT) and isolated top-right RESET key (SW83).
  • Centered top silkscreen title between MH2 (124.0, 4.0) and MH3 (244.0, 4.0).
  • 10 M3 (3.2 mm drill) anti-flex mounting holes (MH1..MH10) placed completely outside all keycap skirts.
• 3dmodels/: Colored VRML 2.0 and STEP 3D models for all Cherry MX key widths (1.00u, 1.25u, 1.50u, 1.75u, 2.00u, and 6.25u with stabilizers and wire).
• keyboard_top.png & keyboard_bottom.png: Raytraced 3D renders of the populated keyboard PCB.
• Componenti_Tastiera_Aleste520.csv: Complete Bill of Materials (BOM).

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2. Decoded Hardware Keyboard Matrix (KM0..KM10 × KM11..KM18)

On the Aleste 520EX motherboard, counter U63 and 2716 EPROM U65 (RFVDKEY.BIN) drive 74LS154 4-to-16 column demultiplexer U80 (KM0..KM10, active-low) and 74LS151 8-to-1 row multiplexer U81 (KM11..KM18), shifting the scanned state into U84 (74LS374) to emulate the Amstrad CPC / MSX keyboard matrix on AY-3-8910 (U18) Port A (X1..X8).

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3. Staggered Physical Layout & Keycap Sizes

• Row 0 (Y = 26.0 mm — Function & System Control Row):
  • ESC (1.00U) | F1 (1.25U) F2 (1.25U) F3 (1.25U) F4 (1.25U) F5 (1.25U) | SELECT (1.25U) STOP (1.25U) CLR (1.25U) DEL (1.25U) | isolated RESET (1.00U) at X = 339.5 mm
• Row 1 (Y = 43.5 mm — Number Row + Numpad Row 1):
  • 1 2 3 4 5 6 7 8 9 0 - ^ \ (all 1.00U) || F7 F8 F9 UP (1.00U)
• Row 2 (Y = 61.0 mm — QWERTY Row + Numpad Row 2):
  • TAB (1.50U) Q W E R T Y U I O P @ [ || F4 F5 F6 DOWN (1.00U)
• Row 3 (Y = 78.5 mm — Home Row + Numpad Row 3):
  • CAPS (1.75U) A S D F G H J K L ; : ] || F1 F2 F3 LEFT (1.00U)
• Row 4 (Y = 96.0 mm — Shift Row + Numpad Row 4):
  • SHIFT (2.00U) Z X C V B N M , . / RETURN (1.50U) || F0 FDOT ENTER RIGHT (1.00U)
• Row 5 (Y = 113.5 mm — Bottom Spacebar Row):
  • CTRL (1.50U) RUS/LAT (1.25U) COPY (1.25U) SPACE (6.25U, 119.06 mm with ±50.0 mm Cherry MX stabilizers) GRAPH (1.50U)