A dream or a hype ?

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By snout

Ascended (15187)

snout의 아바타

04-08-2005, 21:55

Leo - I think implementing the Z80 in FPGA is a much smarter choice, making the One Chip MSX a lot more versatile. You can tweak the Z80 a bit (adding/improving registers or opcoders perhaps, or just increasing its speed) or, if you'd like to let the OCM perform as a different computer, make it perform as an entirely different processor, leaving the Z80 out. As there already is a Z80 implementation that works great and only uses ~9% of the gates available in the OCM I'd say there's little reason for using an external Z80, which basically takes a lot of freedom away.

Besides, not only the Z80 adds to the costs, it also has to be connected to the PCB... but that's just a minor detail Wink

By arnold_m

Master (173)

arnold_m의 아바타

05-08-2005, 14:03

Snout wrote:

...
As there already is a Z80 implementation that works great and only uses ~9% of the gates available in the OCM I'd say there's little reason for using an external Z80, which basically takes a lot of freedom away.
...

From the faq:

In an MSX2 setup, the amount of gates in use can roughly be devided into the following:
Z80 CPU 18.0%
...

By estimation, the Z80 core, the V9938 core and the MSX-MUSIC core can be optimized in order to use only 50% of the Logical Elements they are using at the moment.

Is the faq out of date, or have you taken an optimisation that only exists as an estimation so far into account and presented it as current state of affairs?

I remember the z80-core taking over 30% of LE's, has over 12% been optimised away? how? did it cost any emulation accuracy?

Arnold

By Leo

Paragon (1236)

Leo의 아바타

05-08-2005, 15:34

Yep , I remember that z80 takes 4000 logic element out of 12000.
But I was mentioning this external z80 because the fpga seems a bit small for implementing
for than MSX2+...
I thought about duplicating the VDP so this enables surimpose effets : one vdp image can be
used for huge sprites. And everythin is duplicated : size of vram / #sprite / screen 5 could have
32 colors out of 512 ...
...
Improving the VDP would be very exicting : what about a programable VDP , it could execute
basic Z80 instructions with a subset of registers : only HL and A .

By snout

Ascended (15187)

snout의 아바타

05-08-2005, 18:41

arnold_m: the faq is not out of date, it mentions the current Z80 core using 18% of the gates, but also announces updates of the VHDL code that reduce the amount of gates the Z80, VDP and MSX-MUSIC are using to ~50% of what they currently use, without affecting accuracy. An optimized Z80 core that only uses about 9% of the gates already is available and it looks like it can be implemented in the OCM shortly after its release.

By Leo

Paragon (1236)

Leo의 아바타

06-08-2005, 08:49

9% of the fpga for the Z80 woaa , thats optimization.
What about a Z80 dual core ?

By mars2000you

Enlighted (6267)

mars2000you의 아바타

07-08-2005, 22:26

News on the expensive cable: you only need the cable when an update of the VHDL code in the FPGA chip goes horribly wrong. See it as flashing the BIOS of your mainboard. If a flash fails, you need to replace the BIOS. In case of the One Chip MSX, you can still recover the FPGA chip by uploading the code through the cable. You do not need that cable for ordinary updates, though.

You can see a kit for this special cable on this site, the kit costs 6825 yen :

www.hdl.co.jp/BLKIT/

www.hdl.co.jp/BLKIT/BLKITKAN.s.jpg

www.hdl.co.jp/jpg/blkit_pt.s.jpg

www.hdl.co.jp/jpg/blkitap.s.jpg

By mars2000you

Enlighted (6267)

mars2000you의 아바타

07-08-2005, 22:51

http://dev.ariel-networks.com/blog/nakayama.php?blogid=11

You learn on this site that 2 MSX-DOS tools have been written :

- PLDSAVE.COM converts the FLASH ROM of the OCM into MSX-DOS files

- PLDLOAD.COM rewrites the FLASH-ROM of the OCM from MSX-DOS files, this without the special cable that is only required when all goes wrong (for a complete reinitialisation).

By mars2000you

Enlighted (6267)

mars2000you의 아바타

08-08-2005, 00:20

Let's try to guess the price of a MSX3 OCM (folllowing the scheme adopted by Ascii and presented in the MSX-Magazine 3) :

- MSX1 OCM : 19.800 Yen
- MSX2 Upgrade : 3.000 Yen
- Special cable : 6.825 Yen (see above)
- MSX2+ upgrade : 3.000 Yen
- Turbo-R upgrade : 3.000 Yen
- MSX3 upgrade : 3.000 Yen

Total : 38.625 YEN or the double of the initial price for the MSX1 OCM !

By wolf_

Ambassador_ (9972)

wolf_의 아바타

08-08-2005, 00:26

mhoa.. I doubt that..

Once we all have that cable, we'll do our own VHDL updates and share them Big smile So I estimate it'll stay at the initial MSX1 price + MSX2/cable ..

By snout

Ascended (15187)

snout의 아바타

08-08-2005, 11:46

mars2000you: I know it's your holy mission to bring out everything even remotely negative about the One Chip MSX, taking little care to really sort things out. So let me help you out with a little bit: the special cable that's needed is a Byteblaster2 cable (parallel -> 10 pins FPGA). At Altera's this cable costs a massive 150 dollars, but through other channels the cable can be obtained for about 40 euro's. You can also make one yourself (schedule in PDF over here) I estimate the total cost of creating the cable yourself is about 15 to 20 euros.

Taking non-existant upgrades of which you don't know the pricing once they are to be released just to make the price of the OCM virtually double in your calculation is kinda weak too. Still, I personally would not mind paying for a smashing MSX3 :P

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