[Coco] Re: Coco Repack

[Kevin Diggs]

Hi,

	Forgive my stupidity, but why does reallocating the bits in the
address cut the max memory to 1 Meg (from 2?)?

					kevin

Mark Marlette wrote:

> 

> At 09:03 AM 8/7/2004 -0700, you wrote:

> 

> Alter the page size to lets say 4k and then max. memory will be 1MB.

> 

> 8 bit MMU. Plus an EXTREME going over of NitrOS-9 would have to take place

> to make sure it handled the varying block size. A HUGE task in itself.

> 

> >James,

> >

> >         What about altering the page size? What are your thoughts?

> >

> >                                         kevin

> >

> >jdaggett at gate.net wrote:

> > >

> > > Mark

> > >

> > > The MMU is real simple. It is basically a 2 to 1 4 bit wide multiplexor

> > that feeds a

> > > 16x8 ram. The GIME chip uses a 16x6 ram. Most  likely the package was

> > limited to

> > > 68 pins by Tandy and cost factors. Next standard size up is 84 pins in

> > a PLCC

> > > package. Given that during the 80's it was around 10 cents a pin for

> > package cost,

> > > another 16 pins would have meant another $1.60 for the part.

> > >

> > > I really believe that many of the limitations of the GIME chip is

> > solely due to keeping

> > > costs to a bare minimum.

> > >

> > > The VGA portion is tough to code and will occ py the most territory.

> > That will

> > > determine how big the FPGA is and how much any project like th is will

> > eventually

> > > cost. Most of the free VGA cores are more modern and do not cover CGA

> > > resolutions. Or they are very generic and need more work to make them

> > compatible

> > > to 8 bit buss. One of the nice things is that the software to design

> > the logic and

> > > program the FPGA is free. Right now I am designing the logic for the

> > two registers

> > > at $FF92/3. These registers do a dual purpose. They enable interrputs

> > and also act

> > > as interrupt flags. When you read the register, the flags are cleared

> > while the

> > > interrupt remains enabled. Not a simple D-FlipFlop latch. Most of the

> > rest of the

> > > registers are just that, D flipflop latches.

> > >

> > > Then there will be the 2 to 1 (21) bit wide multiplexor to switch

> > between video

> > > memory and program/data memory. The hardest part is keeping remebering that

> > > the 6809 latches data out of the CPU on the falling edge of the Qclk

> > and latches

> > > data in to the CPU on the falling edge of the Eclk. Have to keep in

> > mind when the

> > > data needs to  be presented to the CPU and when the CPU is passign data to

> > > external devices. After all that the first half of the Eclk cycle is

> > doing display.

> > >

> > > Mark, like I stated in the beginning, I got started with this to use

> > the Coco as a

> > > postion controller and database for my telescopes. One thing that I

> > wanted was to

> > > be able to drive an LCD panel of some type and have OS9 boot from a

> > flash card or

> > > flash memory. I wanted at least 2 megs of sram and not dram. IDE

> > interface and at

> > > least 4 mbytes of flash for storage.

> > >

> > > Real pipe dreams was to add firewire or USB and a parallel port to

> > control a CCD

> > > camera for astronomy.

> > >

> > > So this will start as a home project and I have no idea of where it

> > will go. I  have

> > > toyed with the thought of a FPGA version of the 6309 and run it at say

> > around 15 to

> > > 25 MHz. These are future t hings to work on. I am right now having fun

> > with it and

> > > learning VHDl in the same time frame. It is amazing what you can do

> > with CPLDs

> > > and FPGAs. Some of the software development boards that I designed

> > years ago

> > > would be more flexable and easier had I done a lot of the simple glue

> > logic in these

> > > devices.

> > >

> > > james

> > >

> > >

> > > On 6 Aug 2004 at 18:27, Mark Marlette wrote:

> > >

> > > Date sent:              Fri, 06 Aug 2004 18:27:21 -0500

> > > To:                     CoCoList for Color Computer Enthusiasts

> > > <coco at maltedmedia.com>

> > > From:                   Mark Marlette <mmarlett at isd.net>

> > > Subject:                Re: [Coco] Re: Coco Repack

> > > Send reply to:          CoCoList for Color Computer Enthusiasts

> > > <coco at maltedmedia.com>

> > >         <mailto:coco-> request at maltedmedia.com?subject=unsubscribe>

> > >         <mailto:coco-> request at maltedmedia.com?subject=subscribe>

> > >

> > > > At 10:45 PM 8/6/2004 +0000, you wrote:

> > > >

> > > > The 63B09 = 2MHZ, 63C09=3MHZ and 63D09=4MHZ.

> > > >

> > > > James has quite a project just to do the GIME in a FPGA. Lets not

> > > > overwhelm the project and make it not happen. The paragraph below is a

> > > > HUGE task! Remember this is a hobby for most. To do the software,

> > > > hardware and test takes quite some time. Better yet how many people

> > > > would step forward and help out on it? How about put up the $$$ to buy

> > > > one????? I have over $5k out on the SuperBoard project, that doesn't

> > > > include my time. Love of the machine or stupidity...... :)

> > > >

> > > > It is quite a simple task to make the memory map for the GIME, it is

> > > > ALOT harder to perform all of the functions that is behind each bit.

> > > > The MMU is simple as well. Interrupt and timer functions are a bit

> > > > more complex and not documented the best. The video with all the

> > > > compatibility modes is something else as well. No doubt something to

> > > > be proud of, the GIME is the machine. I have been in direct contact

> > > > with the creators of this beast and it is AMAZING to me that nobody

> > > > has an internal document of it. I also do believe if they had it, I

> > > > would have it as our conversations went.

> > > >

> > > > Mark

> > > > Cloud-9

> > > >

> > > >

> > > > >IIIRC the 6309 is a 4 MHz part? I doubt it will run reliably after

> > > > >6-8 MHz. Even then, it could vary between chips. If you put a 6309 in

> > > > >FPGA you could drop some of the 6809 compatibility and possibly put

> > > > >in some new code, but then you'd lose program compatibility. Not sure

> > > > >how much that would affect NitrOS9 for the 6309 though. Still, if you

> > > > >do a CoCo repack with the joystick ports and replace the bit banger

> > > > >with USB (or two...), it would be a nice system. Wouldn't be 100%

> > > > >CoCo compatible once the ROMs were in place, but would be close.

> > > > >Would be very nice if the DECB ROM could be modified to use a USB

> > > > >floppy, and maybe HD. But DECB really doesn't need a HD for

> > > > >experimental purposes. Some sort of mass storage would be needed,

> > > > >maybe one of those USB "drives" would be easier to code in the ROM,

> > > > >but you'd have to transfer code from a PC to run DECB programs. The

> > > > >only reason I harp on DECB is the ease of programming for

> > > > >experiments. Basic09 is more powerful, it has similarities t

> > > > >  o Pascal, but CoCo BASIC is so darned easy to learn that for simple

> > > > >

> > > > > and/or quick experiments it would be preferred.

> > > > >

> > > > >

> > > > >--

> > > > >Frank Swygert

> > > > >Publisher, "American Independent

> > > > >Magazine" (AIM)

> > > > >*Elite* publication for those

> > > > >interested in all

> > > > >aspects of AMC

> > > > >history,performance,restoration,etc

> > > > >.

> > > > >(AMC,Rambler,Nash,Hudson,Jeep,etc.)

> > > > >http:farna.home.att.net/AIM.html

> > > > >(free download available!)

> > > > >

> > > > >

> > > > >

> > > > >-------------- Original message from coco-request at maltedmedia.com:

> > > > >--------------

> > > > >

> > > > > > Message: 3

> > > > > > Date: Fri, 06 Aug 2004 11:30:48 -0400

> > > > > > From: jdaggett at gate.net

> > > > > > Subject: Re: [Coco] Re: Coco Repack

> > > > > > To: CoCoList for Color Computer Enthusiasts

> > > > > > Message-ID: <41136BE8.14904.E66F7 at localhost>

> > > > > > Content-Type: text/plain; charset=US-ASCII

> > > > > >

> > > > > > Frank

> > > > > >

> > > > > > You are ringt if a FPGA version of the 6x09 were incorporated

> > > > > > along with an FPGA version of the GIME chip, breaking the 10 MHz

> > > > > > barrier will be no problem. Speed control can be done with

> > > > > > external clock ship. One by ICT can derive 1000's of frequencies

> > > > > > from a single crystal frequency. In fact the one chip that I was

> > > > > > looking at, from a 28.6868 MHz cyrstal I can derive over a 1000

> > > > > > different E and Q Clocks for the CPU from 400 KHz to 19 MHz.

> > > > > >

> > > > > > My initial intent was to use a 6309 and my new GIME chip and j ust

> > > > > > see how fast I can over clock the 6309. I have two bytes resevered

> > > > > > in the memory map to address the clock PLL chip.

> > > > > >

> > > > > > Just keep pushing the clock until the chip stops.

> > > > > >

> > > > > > james

> > > > >

> > > > >--

> > > > >Coco mailing list

> > > > >Coco at maltedmedia.com

> > > > >http://five.pairlist.net/mailman/listinfo/coco

> > > >

> > > >

> > > >

> > > > --

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> > > > http://five.pairlist.net/mailman/listinfo/coco

> > >

> > > --

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> >

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