diff --git a/src/devices/bus/isa/trident.cpp b/src/devices/bus/isa/trident.cpp
index 943f0de3432..6f66b17b700 100644
--- a/src/devices/bus/isa/trident.cpp
+++ b/src/devices/bus/isa/trident.cpp
@@ -182,6 +182,7 @@ void trident_vga_device::device_start()
 	m_vblank_timer = timer_alloc(FUNC(vga_device::vblank_timer_cb), this);
 	vga.svga_intf.seq_regcount = 0x0f;
 	vga.svga_intf.crtc_regcount = 0x60;
+	svga.ignore_chain4 = true;
 	memset(&tri, 0, sizeof(tri));
 }
 
@@ -621,6 +622,7 @@ void trident_vga_device::trident_crtc_reg_write(uint8_t index, uint8_t data)
 		case 0x1e:  // Module Testing Register
 			tri.cr1e = data;
 			vga.crtc.start_addr = (vga.crtc.start_addr & 0xfffeffff) | ((data & 0x20)<<11);
+			trident_define_video_mode();
 			break;
 		case 0x1f:
 			tri.cr1f = data;  // "Software Programming Register"  written to by the BIOS
diff --git a/src/devices/video/pc_vga.cpp b/src/devices/video/pc_vga.cpp
index 36512cdd20c..158a1c66a9f 100644
--- a/src/devices/video/pc_vga.cpp
+++ b/src/devices/video/pc_vga.cpp
@@ -711,7 +711,7 @@ void svga_device::svga_vh_rgb8(bitmap_rgb32 &bitmap, const rectangle &cliprect)
 //      line_length = vga.crtc.offset << 4;
 //  }
 
-	uint8_t start_shift = (!(vga.sequencer.data[4] & 0x08)) ? 2 : 0;
+	uint8_t start_shift = (!(vga.sequencer.data[4] & 0x08) || svga.ignore_chain4) ? 2 : 0;
 	for (int addr = VGA_START_ADDRESS << start_shift, line=0; line<LINES; line+=height, addr+=offset(), curr_addr+=offset())
 	{
 		for (int yi = 0;yi < height; yi++)
diff --git a/src/devices/video/pc_vga.h b/src/devices/video/pc_vga.h
index a12ef1c477c..ff381d0340e 100644
--- a/src/devices/video/pc_vga.h
+++ b/src/devices/video/pc_vga.h
@@ -273,6 +273,7 @@ protected:
 		uint8_t rgb24_en;
 		uint8_t rgb32_en;
 		uint8_t id;
+		bool ignore_chain4;
 	} svga;
 };
 
diff --git a/src/mame/misc/pntnpuzl.cpp b/src/mame/misc/pntnpuzl.cpp
index dc8f79352c1..17a5dba53c7 100644
--- a/src/mame/misc/pntnpuzl.cpp
+++ b/src/mame/misc/pntnpuzl.cpp
@@ -392,7 +392,7 @@ void pntnpuzl_state::pntnpuzl(machine_config &config)
 
 	TVGA9000_VGA(config, m_svga, 0);
 	m_svga->set_screen(m_screen);
-	m_svga->set_vram_size(0x200000);
+	m_svga->set_vram_size(0x100000);
 
 	// TODO: runs in external clock mode, needs setter to pc_vga. ~70 Hz is best guess
 	SCREEN(config, m_screen, SCREEN_TYPE_RASTER);