PLCC 44 PROM programming with TL866

Even the retro world is moving away from the regular DIP packaging sometimes. The Atari Falcon, and third party ROM boards from Exxos, use the 27C4096 PROM in PLCC packaging to hold TOS (the operating system). The TL866 with its DIP40 socket cannot obviously handle these, but a quick search shows us that there exists many adapter packages available to purchase that will sort out various types of popular socket formats. Including 44 pin PLCC. However, the most common such adapter isn’t meant for PROMs, but for micro controllers (like the AT89C51 used for the example below). While the pin assignment is almost the same, for the critical purpose of programming the NC pins are swapped.   $ minipro -p AT27C4096@DIP40 -r test.bin Found TL866A 03.2.86 (0x256) Invalid Chip ID: expected 0x1E00F400, got 0xFFFFFFFF (unknown) (use '-y' to continue anyway at your own risk)   If we want to program PROMs with this adapter, we need to perform a slight modification.  

  Simply, but carefully, bridge pins 12-13 and 33-34 on the PLCC adapter (not the DIP!) and off you go.  

  $ minipro -p AT27C4096@DIP40 -w dualtos_swapped.img Found TL866A 03.2.86 (0x256) VPP=13.5V, VDD=6.5V, VCC=5V, Pulse=100us Chip ID OK: 0x1E00F400 Writing Code... 77.79Sec OK Reading Code... 5.58Sec OK Verification OK   Happy programming.