[Coco] Some may call this heresy

[Gene Heskett]

On Tuesday 29 May 2018 00:27:59 CoCo Demus wrote:

> Nope, the 6510 generates a read before a write and I don't understand
> why. I couldn't get a reliable read/write on same port so I messed
> around using a ROM chip to decode:
>
> IO2|R/W|A7-A0
>
> In this way I can make it to read only from port DF76 but write only
> on DF77 and both feed the same port FF76 to the WordPAk. Read to DF77
> is ignored as a write to DF76 as well. I did the same for port FF77
> and FF79.
>
And that demo's why any replacement wordpak anyone designs, should have 
its address changed. Those 4 addresses are the top 2 of one 4 byte wide 
block in the coco i/o scheme, and the bottom two addresses of the next 4 
byte wide block up.  So it occupies 2 4 byte wide blocks of the coco-3's 
very limited i/o space. I did fix mine, there are spare gates on the 
board, and the driver patches to go with the address change are only two 
bytes.

There is enough memory for a 25 line display, and a much larger, more 
readable display can be had if the monitors horizontal hold can be 
coaxed into accepting a signal with an hscan rate of around 18 
kilohertz. All in the chips initialization string in the driver.
>
>
>
> On Mon, May 28, 2018 at 7:13 PM, RETRO Innovations
> <go4retro at go4retro.com>
>
> wrote:
> > On 5/28/2018 2:21 AM, CoCo Demus wrote:
> >> I successfully made an adapter to use the Coco WordPak-RS on a
> >> Commodore 64
> >> and also, using the CP/M cartridge you can run a modified CP/M disk
> >> to use the WordPAK :)
> >>
> >> Watch it:
> >>
> >> https://www.youtube.com/watch?v=XFsHDW1WnaE
> >>
> >> No WordPak-RS were harmed during this video, and I used my cloned
> >> one :)
> >>
> >> Felipe
> >>
> >> Well, color me impressed.  I assume the adapter is:
> >
> > PHI2->E
> >
> > ADDRESS->Address
> >
> > Data-> Data
> >
> > IO1 or IO2 -> !SCS
> >
> > GAME -> CTS
> >
> > ...
> >
> >
> > --
> > RETRO Innovations, Contemporary Gear for Classic Systems
> > www.go4retro.com
> > store.go4retro.com
> >
> >
> > --
> > Coco mailing list
> > Coco at maltedmedia.com
> > https://pairlist5.pair.net/mailman/listinfo/coco



-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>