(I apologize my Tarzan-like english...)
Here there are some informations about MSX2 Hitachi MB-H3.
If you have some cool info about this rare MSX2 and be pleased in share
it, write to me.
And if you "just" have one write to me too. ;)
RGB MSX2 Hitachi MB-H3 connector
(View from female DIN-8 connector at MB-H3 back)
For informations on what monitors can be compatible and schematics of
the generally required sync separator, take a look in MSXPró
3 8 1
Expanding the VRAM
Disclaimer: use this informations under your own risk.
MB-H3 was manufactured originally with just 64kb of VRAM, but we can
easily upgraded it to 128kb. For this we just need some solder iron
practice, 2 DRAM 4464 (64kb x 4 bits) or compatible and one 33 Ohms
I find in one local parts provider the DRAM ICM4464 by Itautec
(Brazilian) for approximately U$1.00 each. Warning: there are another
IC with 4464 number in designation body, but this have 28 pins.
4464 pin assignment (source:
/OE |1 +--+ 18| GND
D0 |2 17| D3
D1 |3 16| /CAS
/WE |4 15| D2
/RAS |5 4464 14| A0
A6 |6 13| A1
A5 |7 12| A2
A4 |8 11| A3
VCC |9 10| A7
With parts in hand, just assemble the two DRAMs in IC19 and IC20
reserved positions. The resistor must be assembled in R39 position.
IC19 and IC20: DRAM 4464
R39: 33 Ohms
Check the connections, and if there's short-circuit exhaustively, clean
it, etc. Connect the mainboard to keyboard and source, and
voilà.. its, everithing!
Put the MB-H3 to work and it must display "VRAM: 128kbytes" in first
splash-screen. Better than this test, if you have DOS, run 'TestRAM' by
Adriano Cunha downloading in his site (A&L Software), to test
every byte of VRAM.
Sources: V9938 manual.
The MB-H3 touch-pad obey MSX standard, so, to play with it, we can use
BASIC and/or BIOS calls.
In BASIC, for example:
5 REM six lines graphics proggie
20 IF PAD(0)=0 THEN 40
30 PSET (PAD(1),PAD(2)),C
40 IF PAD(3)=-1 THEN CLS
50 GOTO 20
PAD(0) returns 0 (zero) if the pen are up and -1 if down.
PAD(1) returns x coordinates.
PAD(2) returns y coordinates.
PAD(3) returns 0 (zero) if blue button are not-pressed and -1 if
But for correct usage you need to put the switch next the joystick 2 in
correct positon (switch it to computer rear side).
Sources: AdMouse On-Line Manual (By Ademir Carchano in MSX-Projetos)
10 photos (~400kB) here.
wmv 5MB video here.