Alex-2-Graf/Leningrad-2-128k-SRAM
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> [English](README.md) | [Русский](README.ru.md)
Following the successful launch of the Leningrad-2-48k project and incorporating community feedback, this version transitions from dynamic RAM (DRAM) to static RAM (SRAM).
Following the successful launch of the [Leningrad-2-48k](https://github.com/Alex-2-Graf/LENINGRAD-2-48k) project and incorporating community feedback, this version transitions from dynamic RAM (DRAM) to static RAM (SRAM).
This architectural shift required a significant redesign of the memory management unit. As a direct benefit, the system memory has been expanded to 128K directly on the mainboard without requiring any external expansion daughterboards.
@ -12,24 +12,26 @@ Additionally, the freed-up PCB space allowed the integration of two YM2149F soun
The final result of these upgrades is the **"Leningrad 2 NEXT 128K + TS 2025"** motherboard. Following hardware assembly, testing, and minor debugging, the project was officially given a new name by close friends: **"Aurora"**.
![](Foto/L2_2.01.jpg)
***
### Revisions & Hardware Modules
#### Mainboard Revisions
* **Revision 2.01** ([Schematics](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM) / [Gerber](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM)) — *Initial release. Features a humorous design note: at the urgent request of the PCB manufacturer, the board text was changed from "Made in..." to "Designed in..." ;)*
* **Revision 2.02** ([Schematics](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM) / [Gerber](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM)) — *The latest stable revision. Adds a power LED indicator and fixes the joystick port routing.*
* **Revision 2.01** ([Schematics](Export/Leningrad%202%20128k%20SRAM%202.01%202025.pdf) / [Gerber](Gerber/Leningrad%202%20128k%20SRAM%202.01%202025%20gerber%20made%20in%20Italy.zip)) — *Initial release. Features a humorous design note: at the urgent request of the PCB manufacturer, the board text was changed from "Made in..." to "Designed in..." ;)*
* **Revision 2.02** ([Schematics](Export/Leningrad%202%20128k%20SRAM%202.02%202025.pdf) / [Gerber](Gerber/Leningrad%202%20128k%20SRAM%202.02%202025%20Gerber.zip)) — *The latest stable revision. Adds a power LED indicator and fixes the joystick port routing.*
#### Bus Adapters & Expansion Boards
* **Nemo-bus and ZX-bus Adapter** ([Gerber](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM)) — *Differs from the previous project version by routing the `/IORQ-GE` signal directly to its intended destination. On older Revision 1 adapters, `/IORQ-GE` went to pin A19 (+beta); it now routes to pin A17. To upgrade a Rev 1 adapter to Rev 2 specs, simply cut the trace going to A19 and solder a jumper wire to A17.*
* **"Yolka" (3x Nemo-bus & 1x ZX-bus) Slot Expansion Board** ([Schematics](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM) / [Gerber](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM)) — *An expansion backplane made possible by the new onboard hardware arbiter.*
* **Upgraded Slot Expansion Board** ([Schematics](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM) / [Gerber](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM)) — *A redesigned backplane where the ZX-bus connector is replaced with a standard Leningrad-2 edge connector. It also adds a dedicated +5V/+12V power input molex. Vintage ZX-bus cards can still be connected here using adapters ([First](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM) / [Second](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM)).*
* **Nemo-bus and ZX-bus Adapter** ([Gerber](Gerber/L2_NS_Rev_1_1_Gerber.zip)) — *Differs from the previous project version by routing the `/IORQ-GE` signal directly to its intended destination. On older Revision 1 adapters, `/IORQ-GE` went to pin A19 (+beta); it now routes to pin A17. To upgrade a Rev 1 adapter to Rev 2 specs, simply cut the trace going to A19 and solder a jumper wire to A17.*
* **"Yolka" (3x Nemo-bus & 1x ZX-bus) Slot Expansion Board** ([Schematics](Export/Back_L2_Nemo_x3_Spec_Ver2.1.pdf) / [Gerber](Gerber/Back_L2_Nemo_x3_Spec_Ver2.1_gerber.zip)) — *An expansion backplane made possible by the new onboard hardware arbiter.*
* **Upgraded Slot Expansion Board** ([Schematics](Export/Back_L2_Nemo_x3_L2.pdf) / [Gerber](Gerber/Back_L2_Nemo_x3_L2_gerber.zip)) — *A redesigned backplane where the ZX-bus connector is replaced with a standard Leningrad-2 edge connector. It also adds a dedicated +5V/+12V power input molex. Vintage ZX-bus cards can still be connected here using adapters ([First](Gerber/Nemo2ZX_BUS_v1.zip) / [Second](Gerber/Nemo2ZX_BUS_v2.zip)).*
#### Keyboard PCB Options
Two mechanical keyboard variants were designed for different mounting styles:
1. **Chassis Mounted:** Designed to fit directly into a computer case ([Gerber](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM)).
2. **Sandwich / Double-Decker Mounted:** Designed to stack directly on top of the mainboard ([Gerber](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM)).
* **Mechanical Switch Support:** Dedicated PCB layouts have been added for **ReDragon-MX-ZT02** ([Gerber](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM)) and **ReDragon_Slim_ZT04** ([Gerber](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM)) switches.
1. **Chassis Mounted:** Designed to fit directly into a computer case ([Gerber](hGerber/ZX-Keyboard_Gerber.zip)).
2. **Sandwich / Double-Decker Mounted:** Designed to stack directly on top of the mainboard ([Gerber](Gerber/L2-40Key_gerber.zip)).
* **Mechanical Switch Support:** Dedicated PCB layouts have been added for **ReDragon-MX-ZT02** ([Gerber](Gerber/L2-40Key-slim-GERBER.zip)) and **ReDragon_Slim_ZT04** ([Gerber](Gerber/ZX-40Key-slim-Gerber.zip)) switches.
***
@ -45,17 +47,17 @@ In general, hardware assembly and tuning are straightforward. The functions of t
## ROM & Video Configuration
* **ROM**: Detailed EPROM files and configuration info can be found [here](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM).
* **VGA**: Firmware and instructions for the RP2040-Zero converter are available [here](https://github.com/Alex-2-Graf/Leningrad-2-128k-SRAM).
* **ROM**: Detailed EPROM files and configuration info can be found [here](ROM).
* **VGA**: Firmware and instructions for the RP2040-Zero converter are available [here](VGA).
---
## Recommended Accessories
* BDI-TR-DOS
* DivMMC
* LGT-Turbo-Sound-emulator
* ZX-EQ Nemo-bus Edition
* [BDI-TR-DOS](https://github.com/Alex-2-Graf/Leningrad2-BDI-TR-DOS)
* [DivMMC](https://github.com/Alex-2-Graf/Leningrad2-DivMMC)
* [LGT-Turbo-Sound-emulator](https://github.com/Alex-2-Graf/LGT-Turbo-Sound-emulator)
* [ZX-EQ Nemo-bus Edition](https://github.com/Alex-2-Graf/ZX-EQ)
---