Скачать или смотреть TI-99/22 Build — Counterfeit 74LS ICs, Board Fixes & DIY PicoPEB (Diagnostic Update)

TI-99/22 Build — Counterfeit chips, board fixes & building a PicoPEB

Welcome back to Earie’s 8-bit workshop and the next episode of the TI-99/22 build. The system still won’t boot, so in this diagnostic update we inspect the board, apply community-recommended fixes, investigate a likely counterfeit 74LS problem, and build a PicoPEB logger to capture CPU commands.

What’s in this episode
• Close board inspection: popped and cracked capacitors (replaced), mislabeled resistors fixed.
• AtariAge community advice and design fixes (remove problematic reset button, remove the rear power LED, replace incorrect crystal with 10.738635 MHz).
• Evidence of counterfeit 74LS ICs from China — why they’re a likely culprit.
• Why we’re switching to 74HCT replacements and where that helps.
• Building a mostly pre-assembled PicoPEB (dabone’s SMD remix of JasonACT’s original design) — and my first SMD soldering attempts after the PSRAM was out of stock at JLCPCB.

Next steps: swap in 74HCT logic chips and re-run PicoPEB diagnostics. Hopefully: first boot.

Links & Resources
• TI-99/22 project (Dan Werner): https://github.com/danwerner21/TI99_22
• PicoPEB JasonACT original design: https://forums.atariage.com/topic/372...
• PicoPEB (dabone SMD remix): https://github.com/dabonetn/ppeb-cr
• Counterfeit IC report (cpuville): http://cpuville.com/News-and-issues.html
• AtariAge forums: https://atariage.com/forums
• TI-99/22 playlist:    • Building the TI-99/22: A Modern Replica of...