[sebhc] Graphics Card

Lee Hart leeahart at earthlink.net
Wed May 16 09:23:32 CDT 2007

Walter Moore wrote:
>> 2. Northwest Digital "Graphics Plus GP19"
> My GP-19 still works and is sometimes hooked up to my H8.  This is the 
> prototype we used to develop the GP-19. It's still fun to see it in 132 
> column mode - it's great for looking at assembler listings.  Set the 
> page length to 49 and an entire page is visible.

Yes! It's amazing that the stock H19 video circuitry was good enough to 
do this, too. One more proof that Heath (and Northwest Digital) did some 
really excellent engineering.

> The same 16K of RAM was used for both text mode and graphics mode.
> In text mode, you could scroll back and look at text which had rolled
> off the top of the screen (took that from an HP system).

The GP-19 had lots of highly useful features like this. Others were the 
on-screen menus, 8-bit character mode (simplified sending mixed text and 
graphics), and control code display mode (for debugging ESC sequences).

> When/if I ever get some 8" drives working, I can put the source in the 
> archive if anyone is interested.  I should also have the original H19 
> source in MACRO-80, and a modified H19 source which added some nice 
> features and improved the speed a lot, also in MACRO-80.

I'd be interested. Also, I can post my Superset source. I copied many of 
the features of the GP-19, and it is also a *lot* faster than the stock 
H19 code (runs at 38k baud without handshaking).
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in    --    Leonard Cohen
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
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