Any interest in a DIY MSX hardware group

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Por megatron

Resident (41)

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17-07-2015, 11:06


I was just wondering is anybody interested in forming a MSX hardware group to build and design a NEW (Open Source) MSX computer in their spare time. A sort of group of like minded people interested in Z80/MSX hardware designing over months (or year/years) a NEW MSX2 machine with schematics/PCB etc all Open Source. This won't be a Kickstart project or anything like that, just hardware people building a New MSX machine to keep the MSX hardware alive, doing it as a hobby.

The aim is to get people into designing Z80/MSX hardware and learning about how to build a microcomputer system on the way. People could work in groups/group or on there own. And post their stuff as they go to let people see how they're getting on.

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Por madscient

Master (193)

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22-07-2015, 17:41


This is a concept of homebrew MSX I imagined before.

Por jltursan

Prophet (2619)

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22-07-2015, 19:16

Have you already checked your old thread?, seems that someone is waiting for you....

Por Xenophon

Supporter (11)

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23-07-2015, 14:58

I was thinking of building/designing a home-brew MSX 2 , but must confess it seemed rather daunting especially as my electronics skills are rather rusty! It would basically be the same spec as an original MSX 2 but using a few more modern ICs to cut costs and board size.also software switch-able between 4 or 8 MHz to give a slight speed increase over original.

MSX 2 (Homebrew) 4 / 8MHz

Z84C0008PEC (DIP 8MHz Z80)
128K SRAM (as these are cheap) DIP32
128K or 64K EPROM (Cheap) DIP28/32
EPM7032SLC44 CPLD as memory mapper programmed using boolean equations to switch ROM/RAM pages
V9938 Video 128K/192K Video RAM with PAL/NTSC / Composite output.
YMZ284 (AY-3-8910 compatible) sound Chip in a small DIP16 package
SN76489 Sound Chip DIP16 to give Colecovision sound (making it easier to port Colecovision games)
CF Card Reader+ PATA Hard Drive interface (possibly using two 8255s)
Keyboard input
Mouse input
Joystick input
Possibly use a EPM7128SLC84 CPLD as glue logic to connect everything together
Other MSX ports (Printer Etc to be connected via CPLD)

Quite a 'Dream' List !

Por tvalenca

Paladin (747)

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23-07-2015, 18:57

the V9938 isn't suitable to anything faster than a Z80 running at 3.57MHz with a 1T waitstate on each M1 cycle. for an 8MHz (7.14MHz) MSX, you will want a V9958. Which is both better and cheaper to buy.

Por Grauw

Ascended (10634)

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23-07-2015, 19:08

Eh? Max access timing between V9938 and V9958 is the same… Also there are plenty of MSX2 computers upgraded to 7.14 MHz, I’ve used a bunch. The 7 MHz circuits slow down on access to the VDP, but this is necessary for both V9938 and V9958.

That said, no reason not to get a V9958 Smile. It’s fully backwards compatible and some MSX2+ software will run even without an MSX2 BIOS.

Por tvalenca

Paladin (747)

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23-07-2015, 21:10

Grauw, I maybe got a little pedant, but the reason I told that is because the V9958 has a /WAIT pin that helps to keep bad behavior applications in line, and no 7.14MHz upgrade I saw in my life worked flawlessly. If I someday design a turbo kit, having a V9958 installed will be required. (it also will require to connect a wire on /WAIT pin from V9958, as it isn't connected on some MSX2+ machines.

Frankly... if someone had asked me, I would have said that the V9938 should never have existed, and the MSX2 should have been released with the V9958 as VDP right away. Or, the V9938 should had V9958 features from the beginning. Pity that Yamaha chips always hit the market too late. (or at least all VDPs)

Por anonymous

incognito ergo sum (116)

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24-07-2015, 02:52

Many times we have discussed about a new possible MSX computer and blah, blah, blah. Why not do we use this thread to discuss about a credible and feasible proposals once and for all? What people want? Don't get me wrong, I'm not criticising the existing ones like 1ChipMSX (or clon), Orbit, MSX Arm or M5X, etc but we know all that this kind of products are not normally so popular among us and we should ask ourselves why. Distrust? Price? Compatibility? Requeriments? Specs? Necessity?

On the other hand we should respond more questions like, is the FPGA based technology the solution now? Maybe the emulators? Should we keep the configuration and specs as close as possible to the MSX standard or break some barriers?...

IMHO the lack of consensus is a big problem here and what better place to talk about this than the MRC? I have always felt that a hypothetical new MSX should be discussed among MSX community. Our MSX computers are really old so perhaps it is not bad idea to discuss about it.

Por hit9918

Prophet (2926)

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24-07-2015, 08:22

the wrestle about a feature list will never end. there is needed a fundamental change.
the question is why the MSX user denies plugging cartridges?
is it maybe that 90% of MSXes got no sane rear slot?

no features and a rear slot with sane expander plugging is my "once and for all" feature proposal Smile

Por Grauw

Ascended (10634)

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24-07-2015, 09:54

tvalenca wrote:

Frankly... if someone had asked me, I would have said that the V9938 should never have existed, and the MSX2 should have been released with the V9958 as VDP right away. Or, the V9938 should had V9958 features from the beginning.

Yes, I can only imagine how different our MSX2 games would have looked!

Por megatron

Resident (41)

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24-07-2015, 10:53

The access speed problem could be quite easily overcome in a NEW design by slowing the clock speed down to 3.58MHz when a I/O instruction is made thus the CPU would run at 3.58MHz or 7.16MHz but all I/O would be a 3.58MHz. This would obviously be quite difficult to do on an existing MSX design. I've seen this type of thing done on 6502/6809 CPU and isn't as difficult as it sounds.

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