[Coco] CP/M OS-9 is back

[Joel Ewy]

On 03/26/2014 08:03 AM, Luis Antoniosi (CoCoDemus) wrote:
> Hi guys,
>
> I got some time improving mt CP/M emulator as you can see in the video:
>
> https://www.youtube.com/watch?v=FiwmUnLTcjY&feature=youtu.be
>
> It's emulating Microsoft Basic. Couldn't test it extensively but it
> seems to be working fine.

Hey Louis,

This is cool stuff.  I thought I'd try it out on my CoCo3FPGA and see 
how fast the emulation is at a nominal 25MHz.  The speed looks great -- 
I was going to shoot a comparison video showing how well CoCo3FPGA runs 
CP/M, but I think I may have run into a bug.

When I try to replicate your program in MS-BASIC, I type the first line 
just as you do in your video, but when I list the program, line 10 reads:

10 FOR N=0 TO 0

Initially I thought I just mistyped the second value.  But in fact, no 
matter what values I use in the FOR loop, it always stores them as '0'.  
I don't know whether the problem is with the emulation, the FPGA's 
CPU09, or just an unhappy interaction between the two. Performance-wise, 
it appears to me that most CP/M programs would be quite comfortably 
usable on the CoCo3FPGA, presuming that they worked correctly.  You 
should see the WordStar screen load up.

Anybody have any ideas what might be wrong here?  Anybody else with 
CoCo3FPGA want to give this a go and confirm my results?

JCE

> I'll be releasing a beta version for you to play with. The emulator is
> 100% assembly (lwasm) and is 7KB only. Only the i8080 is emulated
> although I expect to extend it to z-80 extra instructions later.
>
> It's running on a higher speed than I previous thought. I will release
> the assembly code as well and if you want to help to improve the speed
> feel free to do it. The main bottleneck is the flag converting between
> 6809 -> 8080.
>
> Although I created a lookup table to convert it, the 8080 has extra
> flags or the flag is not changed on the 6809 equivalent instruction.
>
>