how can I rewrite my msx2 nms8280 bios?

take out eprom
and replace with other one wit 2+ content

Nope. You have to place that eprom in. However. If you do not feel so much for trouble just replace the VDP. Many programs will work. Here are the ones I have tested so far and got it working:

F1 spirit (some versions work some don't)
Laydock 2
Space manbow (will use the msx2+ VDP)
sonyc

Otherwise prepare for lots of soldering Make sure you read the articles at the site of bas ditta to find out what you are up against.

Yeah.
The same holds for me. What does he say in those tutorials? They are in Dutch.

I found a diagram in gilberto msx pages, but not sure if the procedure is the ssame for nms 8280 (the one posted is for vg 8235)

Ok here comes the translation:

The first head basicly warns you that you should NOT try to desolder any IC' s from the main board because damaging the main board is an end of story scenario. Always cut the parts loose and remove the remaining pins carefully afterwards.

Requirements:

V9958
74LS02
74LS173
27C256 x 2 (these will replace IC 117 and 119) EPROM A and C
27C512 (this one will replace IC 118) EPROM B
1N41481
2x Capacitor 100 nF

Preparation:

74LS02 shorten pin 1,2,3,4,5,6,8,9,10,11,12,13
74LS02 place 100n F cap bewteen pin 7 and 14
74LS02 connect pin 2,3 and 10 with each other
74LS02 connect pin 4, 8 and 9 with each other
74LS173 shorten pin 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
74LS173 place 100nF capacitor between pin 8 and 16
EPROM B shorten pin 1 and 27
EPROM C shorten pin 20 and 27

Prepare the main print

Remove IC 106
remove IC 117
remove IC 118
remove IC 119

these are basicly the eproms and VDP

Build in:

place V9958 on the position of IC106
Place EPROM A in the empty IC socket 119
Place EPROM B in the socket 118
Place EPROM C in socket 117

solder 74LS02 onto the IC 125 with its remaining pins
solder 74LS173 onto the IC 171

Make a connection between IC106 pin 4 and IC120 pin 10
make a connection between IC106 pin 21 and IC182 pin 14
make a connection between IC106 pin 26 and IC145 pin 24 with a diode inbetween
make a connection between IC106 pin 27 and IC182 pin 7

make a connection between IC117 pin 27 and IC118 pin 27 and IC119 pin 27

and now comes the scary stuff. If you screw something up beyond this point. prep up for a funeral:

Make a connection between IC117 pin 20 and IC101 pin 86!
make a connecton between IC117 pin 20 and connector MY pin 38
Make a connection between IC118 pin1 and IC150 pin 13
make connection between 74LS02 pin 1 and 74LS173 pin 7
make connection between 74LS02 pin 5 and 6 and 74LS173 pin 2 and IC159 pin 4
make connection between 74LS02 pin 11 and 12 and IC 171 pin 1
make connection between 74LS02 pin 13 and 74LS173 pin 15

make connection between 74LS173 pin 1 and IC101 pin 38
make connection between 74LS173 pin 3 and 14 and IC171 pin 4
make connection between 74LS173 pin 9 and 10 and IC101 pin 39

At final attach a piece of metal to the V9958 for extra cooling. Use two spots of glue on the outer parts and thermal paste on the inner parts.

Just to cover my butt. If you try this I am NOT responsible for whatever consequences will follow from this. You have been warned that this operation may turn out into a funeral.