I'm trying to find a viable 4MB RAM upgrade path for my STFM with a C103414-001 Rev 1.1 motherboard.
Board details:
8x NEC 424256-10 (256Kx4) DRAM in two banks (U3-U6, U10-U13) — fully populated, stock 1MB
MMU is marked C025912-38, in PLCC package, soldered directly to the board (not socketed)
Shifter (C025914-38A) is socketed
GLUE is C025915-38A (also visible, not yet checked if socketed)
I understand the standard plug-in kit (item #0035) requires a socketed MMU, which mine isn't — so that's not an option for me.
Since the MMU is a soldered PLCC and not the SMT (80-pin) variant either, I'm unsure which upgrade path applies to my board. Questions:
Is there a known-good way to add 4MB RAM to this specific board revision (C103414-001 Rev 1.1) with a soldered PLCC MMU?
If the DRAM-swap method (8x 1Mx4 DIP DRAM + A9 line + 33-ohm resistor to MMU) is the way to go, which physical pin on the PLCC MMU corresponds to what would be pin 64 on the DIP MMU package? The PLCC pin numbering obviously doesn't match the DIP pinout 1:1, so I want to get this right before I start soldering.
Has anyone here done this specific mod on a C103414-001 board with a PLCC MMU? Would love to see photos/wiring if so.
I'll attach a couple of photos of the board and the MMU area. Any pointers appreciated — thanks in advance!
(KI helped me with my bad english
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