Leningrad2-Upgrade-Kit

Memory Expansions and AY/TS for Leningrad-2.

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This repository contains hardware expansion board projects designed for the RAM and sound upgrade of the "Leningrad-2" home computer.

These modules allow you to upgrade the stock 48K base model to a full 128KB or 256KB system. This expansion is essential for running modern homebrew games, advanced demos, and heavy software.

The boards are designed with a primary goal: minimizing messy wire-wrap modifications ("spaghetti wiring"). They connect directly to the system expansion slot, transforming the basic Leningrad-2 48K into a powerhouse 128K+ class machine.

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🎸 All-in-One Module Features

• Memory: Upgrade to 128KB (Standard Spectrum 128 mapping) or 256KB using classic DRAM chips.
• Sound: Integrated AY-3-8910 sound chip (or YM2149F equivalent).
• Turbo Sound (Optional): Supports dual AY/YM chips to achieve full 6-channel Turbo Sound capabilities.
• Beep Mixer: The standard motherboard Beeper signal is mixed directly into the main audio channel output.
• Circuitry: Standard port decoding logic (#7FFD for memory paging and #BFFD/#FFFD for sound chip registers).
• Compatibility: Full support for games and demos requiring official memory bank switching.

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🧩 Hardware Construction & Connection (Bus Through-Port)

The upgrade boards feature a Bus Through-port design. They plug directly into the main system connector of the Leningrad-2, while providing an identical expansion slot connector on top.

• Plug-and-Play: This allows you to stack other peripherals—like BDI (TR-DOS) or DivMMC controllers—directly on top of this expansion board without using flat ribbon cables.
• Motherboard Integration: Optimized for seamless operation with my custom version of the Leningrad-2-48k.
• Universal Compatibility: The board can also be wired to any standard vintage or third-party version of the Leningrad-2. In this case, you will only need to manually route a few core control signals according to the provided schematic.

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📦 Modular RAM Replacement (RAM Plug-in Board)

As an alternative to chip stacking ("piggybacking"), this project includes a specialized adapter PCB that holds 16x KR565RU5 (КР565РУ5 / 4164) DRAM chips to replace the stock computer memory.

• Installation: The adapter plugs directly into the original RAM IC sockets (or footprints) on the Leningrad-2 motherboard.
• Universal Fit: The pin group layout completely matches the original RU5 memory chip placement found across all known Leningrad-2 PCB revisions.
• Key Advantage: No messy chip stacking. It provides a clean install, a reliable contact interface, and superior cooling/ventilation for the RAM chips.
• Solderless Upgrade: Equipped with thin male pin headers (PLS-type) that slide perfectly into standard round-hole machined IC sockets on the mainboard. It preserves the clean, aesthetics and long-term hardware reliability.

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🛠️ Project Modules

1. Leningrad 2 Expansion 128k & AY-3-8910 (YM2149F)

• Schematics | Placement | Gerber Files

2. Leningrad 2 Expansion 128k & Turbo Sound 2x YM2149F (AY-3-8910)

• Schematics | Placement | Gerber Files

3. Leningrad 2 Expansion 256k & Turbo Sound 2x YM2149F (AY-3-8910)

• Schematics | Placement | Gerber Files

4. RAM Plug-in Board 2x64

• Schematics | Placement | Gerber Files

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🔧 Mainboard Preparation

• For my custom Leningrad-2-48k revision: Preparation is as simple as configuring the onboard jumpers JP5 to JP11 (clearly labeled on the PCB silkscreen).
• For stock/vintage motherboards: Please consult the descriptive documentation and schematics provided in this repository to properly tap the missing address lines.

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💾 Memory Testing Software

To verify your new memory configuration, you can use the following diagnostic tools included in the repository:

• GTEST
• HFT