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Low cost Z80 20MHz MSX board...

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By lezanderson

Resident (36)

lezanderson's picture

03-08-2012, 14:02

Hi.

I'm looking to design a minimal low cost 20MHz Z80 board , which is MSX2,MSX2 turbo compatible. The general specs are below.

PCB approx 220 x 160 or smaller
Z84C0020 CPU 20MHz
V9958 VDP
128k or 512k SRAM
64K EEPROM
512K FLASH backup RAM
EMP7128 or better CPLD glue logic
Com 2 serial port DB9
Com 2 serial port DB9
LPT1 DB25 Parallel port
PS2 Mouse + Keyboard
DB9 Joystick ports
9-15V DC input
7805 Voltage regulator

The finished board should cost about £50

Anyone interest just email..

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By WORP3

Paladin (864)

WORP3's picture

03-08-2012, 15:24

I wouldn't go for the EPM7128 cpld as they are hard to get these day's !

By WORP3

Paladin (864)

WORP3's picture

04-08-2012, 11:46

Is the V9958 VDP still available on the market ?

By tcruise

Master (134)

tcruise's picture

07-08-2012, 13:43

Count me in, would love to build one. As long as the VPD's and other parts are generally available.

By Capitan_Goto

Master (168)

Capitan_Goto's picture

07-08-2012, 14:50

Great Idea and great project. Just a couple of questions: can this design supports floppy, sd or rom cardtridge slots? This could be superb!!

Greetings

By msd

Paragon (1515)

msd's picture

07-08-2012, 19:59

Why not msx2+ compatible, since you use the v9958?

By Prodatron

Paragon (1843)

Prodatron's picture

07-08-2012, 20:08

Having catridge slot(s) and/or OCM-like sd card reader would be really helpfull. Then it should be a nice replacement for the (already rare) OCM!

By hit9918

Prophet (2932)

hit9918's picture

07-08-2012, 20:22

I wanted to say.
There is the issue of cpu brake for VDP speed limit.
And 3.57Mhz mode.
Have you thought of these issues.

By Sky_hawk

Champion (267)

Sky_hawk's picture

07-08-2012, 20:47

Nice, add a FT245R to the design and you will have nowind (msx <-> usb host) too Smile

By msxegor

Master (183)

msxegor's picture

22-08-2012, 17:01

Hi, i started a very similar project codenamed MSX2011 in 2011 as you may guess. No time to finish PCB design, unfortunately. Have Eagle schematics and half-traced board. May require some optimization.
Specifications:
33 Mhz Z180
512K or 1M SRAM memory, 128K flash (BIOS + subrom + 16K DOS1 diskbios + 64K DOS2.
YM2203 sound chip (don't ask why, i just like it)
Glue logic - Altera EPM7128SLC84
Keyboard and clock implemented in AtMega8 + any SPI clock chip
VDP (9938 or 9958) with SRAM VRAM
SD interface

By fzanoto

Master (190)

fzanoto's picture

22-08-2014, 16:03

msxegor wrote:

Hi, i started a very similar project codenamed MSX2011 in 2011 as you may guess. No time to finish PCB design, unfortunately. Have Eagle schematics and half-traced board. May require some optimization.
Specifications:
33 Mhz Z180
512K or 1M SRAM memory, 128K flash (BIOS + subrom + 16K DOS1 diskbios + 64K DOS2.
YM2203 sound chip (don't ask why, i just like it)
Glue logic - Altera EPM7128SLC84
Keyboard and clock implemented in AtMega8 + any SPI clock chip
VDP (9938 or 9958) with SRAM VRAM
SD interface

msxegor,
you can send it for us ?

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