Editing Atari 600XL General Maintenance (section)

=== Internal RAM Upgrades ===
If the unit has been internally upgraded:
* '''Inspect solder joints''' on any added wires or IC sockets. Poor soldering is the most common cause of failure in modified units.
* '''Check IC socket contacts''' — If upgrade RAM chips are in sockets, remove and reseat them periodically to prevent oxidation-related contact failures. Consider replacing single-wipe sockets with dual-wipe types for improved reliability.
* '''Verify RAM chip compatibility''' — Acceptable DRAM chips for the 600XL include 4164, 4264, 4464 (for 64 KB upgrades), and 41256 (which will function at the required density). The speed rating should be 200ns (-20) or faster.