[Coco] CoCo3FPGA new 640x450 256-color graphic mode

[Dave Philipsen]

Right now, the CoCo3FPGA has 100% stock ROMs. The accesses to the FD 
controller are 'trapped' in hardware and re-routed to a 
hardware/software core that implements the drivewire support.  I *think* 
Gary would like to keep the ROMs stock to keep things as 100% compatible 
as possible in the firmware.  If someone wanted to implement HDBDOS or 
modify the disk ROM on their own this would be very possible.  The ROM 
code resides in a flash chip on the DE1 that is user programmable.

The NitrOS9 works with a low-level driver that Gary wrote that works 
underneath the superdriver. It reads and writes directly to its own OS9 
partition on the SD card.  In other words, it's formatted just like an 
OS9 hard drive.  The idea of bringing the signals out for a FD 
controller may have some practical utility but why would you connect a 
CoCoSDC when you've already got an onboard SDC?

Actually, I've already read/written sectors to the SD card under DECB.  
I used Gary's code for the OS9 driver to put together some quickie 
routines to do this.  The raw read/write sector routines take less than 
600 bytes of machine code.


Dave Philipsen



On 2015-09-30 15:01, Barry Nelson wrote:
> So what is needed to get the SD slot working in Extended BASIC? I have
> heard that it is working in OS-9/NitrOS9, so I am guessing that all
> that is probably needed is an updated Extended Disk Basic ROM? Maybe a
> modified HDBDOS that has the read write routines replaced to point to
> the SD card? How does the OS-9 support work? Does it read/write
> directly to the card or to a FAT file on the card? Also I wonder how
> hard it would be to bring all the signals for the CoCo I/O bus out to
> external pins so a real disk controller or a CoCoSDC could be used?