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(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. ;)

MSX2 Hitachi MB-H3



PiratasDoTietê RGB connector

RGB MSX2 Hitachi MB-H3 connector
 1 R
2 G
3 B
4 CSync
5 +5V
6 Audio
7 +5V
8 GND

7 6
3 8 1
5 4
2
(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 site.

PiratasDoTietê 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 resistor (orange,orange,black). 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: http://www.qsl.net/yo5ofh/data_sheets/mem-ram.htm):

64kx4 DRAM
      +---+--+---+
/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.

Have fun!

Sources: V9938 manual.



PiratasDoTietê The touch-pad

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
10 SCREEN5
20 IF PAD(0)=0 THEN 40
30 PSET (PAD(1),PAD(2)),C
40 IF PAD(3)=-1 THEN CLS
50 GOTO 20


where:
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 pressed.

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)


PiratasDoTietê MB-H3 Photos

10 photos (~400kB) here.


PiratasDoTietê MB-H3 Video

wmv 5MB video here.


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rymaeda@yahoo.com
http://www.ioxio.com.br