[Coco] MC6847 External ROM boards finally ready...

[Zippster]

Hi Mike,

It’s on it’s way.

USPS tracking # 9505 5111 7680 5293 4382 37

Thank you!

- Ed


> On Aug 25, 2015, at 3:45 PM, Craig Michael <mdcmike at sbcglobal.net> wrote:
> 
> w00t!! Money sent! Can't wait to get my paws on this! :-)
> Mike 
> 
> 
>     On Sunday, August 23, 2015 1:47 PM, Zippster <zippster278 at gmail.com> wrote:
> 
> 
> Well, they are finally ready!
> 
> The board is specifically designed to fit American CoCo2 motherboards, but should work in
> any 6847 socket, as long as you have physical clearance to plug it in.
> 
> It supports either a 27C256 or 27C128 or other ROM/EPROM with the same pinout.
> At the end of the email is information on usage of the 7 position DIP-switch.
> 
> There are 12 character sets on the ROM that comes with it, several are variants of the same
> typeface tweaked for better appearance in some situations.
> 
> The first 2, supplied by Al Hartman, are the original Lowerkit character sets by Dennis.
> The 3rd, also from Al, he believes, is a set made by Marty Goodman from the set on a IBM PC graphics
> card way back when.  The others I put together based on some fonts found out on the internet.
> 
> Here are some pics of the included character sets…
> <https://drive.google.com/open?id=0B1sgl615FlGnfl9ZMWhqeGstWlRIYnRHRVJSaHUyeVRaa29ScVdmWmZUWEFlakM5WW1GUHc <https://drive.google.com/open?id=0B1sgl615FlGnfl9ZMWhqeGstWlRIYnRHRVJSaHUyeVRaa29ScVdmWmZUWEFlakM5WW1GUHc>>
> 
> I put together an Excel sheet that makes it easy to create sets.  On the right side of the sheet is the 
> hex code for the set, which can be copied and pasted into a hex editor to make a .bin file.
> Here are the sheets I used to make the ROM.
> <https://drive.google.com/open?id=0B1sgl615FlGnfmdlMnoxVWlmV1RxTjhSb09fTGhsblpCWHAwbEdUY2E2X0ZVQ3BvTW1DS2c <https://drive.google.com/open?id=0B1sgl615FlGnfmdlMnoxVWlmV1RxTjhSb09fTGhsblpCWHAwbEdUY2E2X0ZVQ3BvTW1DS2c>>
> 
> Hopefully we can make some more cool character sets for the 6847.  If you don’t have an eprom burner
> already, this might be a good excuse to get one.  :)
> 
> -------------------------------------------------------------------------------------------------------------------------------------------
> 
> I built 28 of these all together, 17 are spoken for, and I’m keeping 3, so there are 8 still available for
> anyone interested in experimenting with some alternate character sets for the MC6847.
> 
> The boards are $32 ea + shipping.  Shipping is $5.95 in the US, $15.00 internationally.
> My Paypal is zippster278 at gmail.com <mailto:zippster278 at gmail.com>
> 
> Also, if anyone needs an MC6847 because they put a socket in or something, I have a number of these available ($6).
> 
> Ok, I think that’s it.  Thanks guys!
> 
> - Ed
> 
> 
> 
> 
> 
> MC6847 External Character ROM - REV 03
> 
> DIP SWITCH SETTINGS
> 
> 1 - Enable External ROM
> 2 - Inverse mode
> 3 - All Caps mode
> 
> 4…7 - Bank selection 0…15 in binary
> 
> 
> 1) - Enable External ROM
> Selects between MC6847’s internal ROM, and our external ROM.
> 
> 2) - Inverse mode
> Inverts the normal use of the INV line.  What was black on green is now green on
> black and vice versa.
> 
> 3) - All Caps mode
> To accommodate certain programs that are expecting inverted uppercase when
> the computer calls for a lowercase character from the internal ROM, this mode 
> does the following.
> 
> Decodes for any VDG calls for a lowercase character in external ROM (610h - 7A0h),
> and offsets the address lines to the ROM chip for uppercase.  Also triggers inverse mode
> for that character.
> 
> The results will be like using the internal MC6847 ROM, but with the external
> character set.  Inverted uppercase in place of true lowercase characters.
> 
> 4…7 - Bank Selection
> Selects one of 16 character banks to use in binary
> 
> 
>         Bank 0    Bank 1    Bank 2    Bank 3
> 
>         0 0 0 0    0 0 0 1    0 0 1 0    0 0 1 1
>         - - - -    - - - -    - - - -    - - - -
> Switch  4 5 6 7    4 5 6 7    4 5 6 7    4 5 6 7    etc….
> 
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> 
> 
> 
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