The 'NMK-111' and 'NMK-112' are two custom chips found on many arcade PCBs from NMK manfacturer.
They share the same QFP64 package :
Technically speaking the 'NMK-111' is used for latching RGB output (just before the 'NMK-007' R/2R DACs) and handling palette RAM. It's also used for handling background VRAM.The 'NMK-112' is used for OKI MSM6295 audio samples ROM banking.
Some time ago I sent 'Furrtek' (https://x.com/furrtek) a couple of chips, he promptly decapped and imaged the silicon dies.After some time 'Recreativos Piscis' (https://x.com/Recre_Piscis) identified the cells of the dies making schematics of the internal structure and writing Verilog code of it.The last step was making a proper replacement of the chips, this is what I made using the castellated half holes design in order to mimic the QFP64 package.I chose a small CPLD to embed the logics :
Both replacements worked fine at first try.Here is testing of the 'NMK-111' reproduction as RGB latch on a Macross PCB :
View: https://youtu.be/dRoUz3GVPPA
Here is testing of the same reproduction as background VRAM handler :
Here is testing of the 'NMK-112' reproduction :
View: https://youtube.com/shorts/14BoHLLGxvk
A huge thank again to 'Furrtek' and 'Recreativos Piscis' for their brilliant work without which this result would not have been possible.
They share the same QFP64 package :
Technically speaking the 'NMK-111' is used for latching RGB output (just before the 'NMK-007' R/2R DACs) and handling palette RAM. It's also used for handling background VRAM.The 'NMK-112' is used for OKI MSM6295 audio samples ROM banking.
Some time ago I sent 'Furrtek' (https://x.com/furrtek) a couple of chips, he promptly decapped and imaged the silicon dies.After some time 'Recreativos Piscis' (https://x.com/Recre_Piscis) identified the cells of the dies making schematics of the internal structure and writing Verilog code of it.The last step was making a proper replacement of the chips, this is what I made using the castellated half holes design in order to mimic the QFP64 package.I chose a small CPLD to embed the logics :
Both replacements worked fine at first try.Here is testing of the 'NMK-111' reproduction as RGB latch on a Macross PCB :
Here is testing of the same reproduction as background VRAM handler :
Here is testing of the 'NMK-112' reproduction :
A huge thank again to 'Furrtek' and 'Recreativos Piscis' for their brilliant work without which this result would not have been possible.
