1.5 KiB
ROM Selection and Configuration Guide
The "Leningrad-2 2025 Revision" PCB provides flexible options for installing ROM chips. You can use standard vintage EPROMs or modern alternatives depending on your goals.
Supported ROM Chips
1. **Standard 48K Setup:**
* **2764 (К573РФ4/6)** — Requires two separate chips. One holds the lower part of the ROM (Basic-48), and the other holds the upper part.
* **27128 (К573РФ8)** — A single chip that holds the entire 16 KB ZX Spectrum 48K ROM.
2. **Expanded Setup (with TR-DOS / BDI):**
* **27256** — Allows you to store two different versions of TR-DOS or customized firmware.
* **W27E256** — A modern, electrically erasable (EEPROM) drop-in replacement for the 27256. Highly recommended for easy flashing.
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## Jumper Settings for ROM
* **JP4 (ROM Type Selection):**
* **Short** this jumper if you are installing **two 2764** chips.
* **Leave Open** if you are using a single **27128** or **27256** chip.
* **J12 (TR-DOS Firmware Selection):**
* Active only when using a **27256** ROM. It switches between the two firmware banks stored on the chip.
* **JP5–JP9 (Memory Expansion Support):**
* Must be soldered/shorted to ensure correct address lines routing for future memory expansions and multi-bank ROM configurations.