The 2024 Advanced PCB Remake of the Atari 800XL System Board uses 4 custom programmed chips. They are as follows:

EMMU (U26): The EMMU, or Extended Memory Management Unit, controls the SRAM banking. In the event that the board is to be configured for 64k only, this chip is optional. This chip requires programming for your memory management scenario, such as 320k or 128k with XE banking, etc.

GLU (U2): The GLU, or General Logic Unit, controls the SRAM and I/O chips. This chip also controls other features that would normally have been controlled by separate chips.

MMU (U3): The MMU, or Memory Management Unit, is a custom programmed ATF22V10C that monitors the address bus lines and enables other chips based upon the called address.

ROM (U4): The ROM contains the operating system and BASIC programming language. As there are two possible options, for the ROM/BASIC combination, they are as follows:

• Bank 1 -- Atari OS Revision 3, with a fix for self test bank testing, and Atari BASIC Revision C.
• Bank 2 -- OS 6.42 (or newer) and Altirra BASIC 1.59.

Chips can be ordered separately.

Each chip is programmed and tested prior to shipping.