[Coco] Altera DE1 - CoCo3FPGA suggestions

[tim at franklinlabs.com]

I would add a few items...


The screen fonts are not correct. They are shifted up to the top of each font
space. If memory serves, there's 2 scan lines at the top on each character. This
doesn't include the block characters. They are fine.

Also, and I know this is a BIG also, release the source. I've been working with
the DE-1 for about 1 1/2 years now and know it quite well. I would like to have
at some custome mods to his code like implementing the SDRAM instead of the SRAM
as it's base. This would give the CoCo(4) as full 8 meg of memory for all sorts
of game than Nick can write! :o)

With the source above, the on-board stereo sound chip can also be implementd for
some awesome game sounds coming from Nicks Fortress game (right?)  LOL.

I have many more!!!

On February 20, 2014 at 5:40 PM Nick Marentes <nickma2 at optusnet.com.au> wrote:
> Now that I have had a played with my DE1 board running the current
> version of the CoCo3FPGA, I would be completely out of character if I
> didn’t have a list of suggestions I see as possible improvements to the
> design. :)
>
> Here is my Altera DE1 -CoCo3FPGA wishlist…
>
> CPU SPEED
>
> Currently, the CoCo3FPGA runs at the original CoCo speed of 0.89 Mhz and
> when put in the double clock speed mode (&HFFD9=1) runs at a speed
> dependant on the position of switches 0 & 1 (1.78, 4.17, 12.5 or 25 Mhz).
>
> My suggestion is to do away with all the intermediate speeds and simply
> have 25 Mhz as the high clock speed. Would anyone use anything other
> than the fastest?
>
> I also would redefine the switch definitions and utilize just a single
> switch.
>
> When switch 0 is off, CoCo3FPGA should operate like a normal CoCo3 with
> 0.89Mhz in normal clock mode and 1.79Mhz at double clock mode. This is
> for compatibility.
>
> When switch 0 is on, then both clock modes (normal and double) should
> operate at 25Mhz. This makes everything run fast even if they don’t
> activate double clock mode.
>
> I don’t see the need for 2 clock speeds. Everyone will tend to want to
> run it at it’s fastest.
>
> VIDEO SCANLINES
>
> Define the switch made free after the CPU SPEED change to act as a
> Scanlines ON/OFF switch.
>
> Currently, any CoCo3 video mode with a maximum of 225 scanlines is being
> drawn twice to make up the 480 VGA style display. This is knoiwn as Scan
> Doubled. When a new 480 scanline mode is activates, this doubling of
> scanlines is turned off to provide a full res 480 line VGA display.
>
> When switch 1 is on, video for modes 225 scanlines or less should be
> handled with Scan Doubling as it currently is.
>
> When switch 1 is off, video for 225 mode scan lines are drawn as 1
> normal scan line and 1 blank (black) scan line to simulate the scan
> lines of a classic non VGA monitor. This gives a more “authentic” look
> to the display and tends to make games look better.
>
> SERIAL PORTS
>
> The bit banger serial port should be moved to the add-on analogue board
> along with the 2 joystick ports. The on board serial port of the DE1
> should become a second real serial port. This serial port can be used as
> emulating the Deluxe RS-232 Pak port.
>
> SOUND
>
> I would not bother emulating the Orchestra 90 or Sound & Speech Paks.
> Little software uses these anyway. I would be looking at implementing a
> new sound system, maybe leveraging off the CoCo’s DAC mono sound system.
> (NEEDS MORE THOUGHT)
>
> MULTI-PAK
>
> I would do away with the emulation of the multi-pak and have the disk
> controller and Disk Basic support created as a Disk Controller cartridge
> plugged directly into the CoCo.
>
> All extra hardware such as RS-232 and Sound Paks should be built in to
> the new CoCo3FPGA as a single design.
>
> DRIVEWIRE AND SD CARDS
>
> Support the Drivewire protocol via the onboard RS-232 port of the DE1
> board (as it currently is) but also offer saving/loading DSK’s to the SD
> Card. It wouldn’t be so important to run a floppy disk controller
> emulation to allow 100% compatibility with software that provides its
> own disk routines. This sacrifice can be made to simplify the addition
> of being able to use the onboard SD Card. OS-9 won’t be a problem.
>
> I’m not sure but we may not need a FAT file system on the SD Card for
> compatibility of the files on a PC. Instead, we could add files to the
> SD Card from the PC using the Drivewire link.
>
>
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