On Fri, 26 Mar 1999, Maarten ter Huurne wrote:
> At 05:25 PM 03/25/99 -0300, you wrote:
>
> >I don't think that (mega)ROM cartridges are interesting. They're hard to
> >copy, unmodifiable (in principle) and much expensive.
>
> They are nice if you collect games. But if you only want to play them, disk
> combined with mappper/MegaRAM is easier and cheaper.
Nice to collect games? But if you're a game collector, you'll want a lot
of games, and cartridges will use too much space in your room. Disks are
phisically much more compact, and this is a good advantage for game
collectors.
> >Some Brazilian guys are fanatical crackers but not for piracy, just for
> >fun! Japanese software was copy protected because they knew that WE would
> >copy it, not the most part of the Japaneses.
>
> I don't think a commercial company would care if their games are copied in
> a country where they aren't available in the stores.
I do, else, there's almost no reason for their copy protection.
> >> Cartridge is extra quality (no loading time, more durable) compared to
> >> disk. Also, it is harder to copy.
> >
> >And much much much more expensive! The cost/benefit relation is much
> >poorer than for disks.
>
> Most of what you pay for a game is not the hardware, but the development.
> Even if ROM hardware is a lot more expensive than disks, it will make only
> a small difference on the selling price.
This is true only nowadays. In that time, EPROMs were very expensive.
> >> Henrik Gilvad once told me.
> >
> >Is he the guy that created the IDE interface for MSX?
>
> Yes. And also the MoonSound, GFX9000 and some other hardware.
So, I would say that he is the "Ademir Carchano" from the Neatherlands!
:-)
> >> >Then, there's still a chance only for Turbo-R.
> >>
> >> The built-in FDC can handle HD according to Henrik. But you would need to
> >> write a new diskROM...
> >
> >Yes, and some hardware modifications, too.
>
> My turbo R already has a HD drive inside, to replace the broken original
> drive. Other modifications wouldn't be necessary, would they?
To be a replacement, no. But if you want to use the 1.44Mb capabilities of
your FDC, at least will need to allow the photo-diode signal from your
drive to be connected to the FDC. Remember: this photo-diode indicates if
a high density (1.44Mb) disk is being used.
> >Some people say that WD2793 can handle 500kbit/s transfer rate. Is it
> >true?
>
> I'm not sure. I heard that FDCs of MSX2s (don't know the part number)
> weren't fast enough. But I've never verified that.
Last year I made a simple test, connecting a 1.44Mb drive in my port based
interface. With 720kb disks it works, but with 1.44Mb disks it doesn't.
Perhaps increasing the value of the cristal (i.e., exchanging the cristal)
it can work. Am I speaking nonsense?
> >My idea was a buffer for an entire track (or maybe cylinder?)
>
> Would that make any difference in performance?
> I think that if the "read sector" command can be given within the time a
> sector gap takes to pass the drive head, reading single sectors will
> already occur at top speed.
The main idea is: I want to make smaller sector gaps, then I can format a
track with 1 more sector, increasing disk capacity. With small gaps, the
time won't be enough, and so it would be necessary to make an entire track
buffer.
> >> It would be a real benefit:
> >> - 720K disks are hard to find, 1.44MB disks are still available everywhere
> >> - double the amount of data fits on a single disk
> >> - disk transfer rate is doubled, making your MSX load faster
> >> Anyone interested in making a prototype?
> >
> >I am interested, but I don't know how should I create a diskrom compatible
> >with the common diskroms.
>
> A diskROM for 1.44MB disks has two main features:
> - sector reading using the new floppy interface (easy to make)
> - support for 1.44MB floppy filesystem (may be difficult?)
Then, your idea is to use a common diskrom, with the least modifications
possible. The performance won't be very good, because standard disk
interfaces has poor performance (compare with a PC interface, for
instance).
> Anyway, the person who makes the hardware doesn't have to worry too much
> about the software. Designing the hardware and designing a sector read
> routine is something that should be done together. But all the other
> modifications to the diskROM are purely a software issue.
I was thinking to create an entire new disk interface, but I don't know
how the disk system variables related to work. So, I don't know how to
create a better disk interface with backward compatibility.
> >The biggest problem is that I don't have enough time, nowadays.
>
> A big problem for many MSXers... :(
Perhaps Henrik Gilvad can implement a 1.44Mb interface using FPGA's. Since
he has a good MSX hardware experience, he can do it spending much less
time.
Greetings from Brazil!
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Marco Antonio Simon Dal Poz http://www.lsi.usp.br/~mdalpoz
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