[[File:Terje GX4000-MC0123B-K3.jpg|100px|left]]
* '''Board: 2700-017P-3, MC0123B, Copyright 1990, K1'''
* R153 installed (near SCART connector)
* NR2 (between CPU and PSG)
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[[File:GX4000 PCB Top.jpg|100px|left]]
* '''Board: 2700-017P-4, MC0123C, Copyright 1990, K1''' ([[Media:Terje GX4000-MC0123C-K1 unrotated.jpg|other picture]])
* R153 not installed (near SCART connector)
* R135-R142 instead of NR2, R1/R2/C2 rearranged (between CPU and PSG)
* bigger R181, D180/R181 rearranged (near RGB monitor connector)
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[[File:Terje GX4000-MC0123C-K2.jpg|100px|left]]
* '''Board: 2700-017P-4, MC0123C, Copyright 1990, K2'''
* Looks same as above (only the "K2" text near the LED changed).
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