MTXPlus⁺ uses a Yamaha V9958 VDP, designed for MSX 2+, it is backward compatible with the Texas Instruments TMS9918 used in the original MTX computer.

Using an MTX compatible ROM, MTXPlus⁺ will be limited to the video features provided in the original MTX.

 

VDP Feature Comparison
Computer		MTX/MSX	MSX2		MSX2+ & MTXPlus+
VDP		TMS9918	V9938		V9958
Video RAM (min/max)		16KB	128KB (64/192)		128KB (128/192)
Resolution : text		24 x 40	24 x 40		24 x 40
		24 x 32	24 x 32		24 x 32
			24 x 80		24 x 80
Resolution : pixels h x v		256 x 192	512 × 212	256 × 212	512 × 212	256 × 212
Colours		16	16 from 512	256	16 from 512	256
					256×212 YJK	256×212 YJK/RGB
					19268	12499
Sprites	Number	32	32		32
	Colours	1	16		16
	Max per line	4	8		8

 

Audio

The MTXPlus+ Video board also contains the sound interface, comprising the same chip used in the original MTX, a Texas Instruments SN76489 Programmable Sound Generator.

 

 

 

References:

Roger Samdal's Spectravideo site, VDP page

GR8BIT project, Eugeny Brychkov, GR8BIT Knowledge Base article on adding Composite and S-Video output (KB0014).