[sebhc] Graphics Card

Lee Hart leeahart at earthlink.net
Tue May 15 13:06:41 CDT 2007

> "The base H-89 had no graphic modes, just 33 graphic characters. At 
> least two different add-on boards were created that gave the H-89
> bitmapped graphics capabilities, but I'm pretty sure they both
> required hardware modifications to tie them in to the terminal board
> - this was not a simple plug-in expansion card." ...

There were at least 6 graphics add-on boards for the H19/H89:

1. Cleveland Codonics "Imaginator"

This was a board the size of the H19 TLB (Terminal Logic Board). It was 
designed to go in the unused CPU board slot in an H19. Later, they 
figured out it could go in an H89 by mounting it horizontally above the 
CRT (as I mentioned for testing the CPU board).

The Imaginator added a graphics plane to the H19 terminal with 16k of 
bit-mapped memory (512x250). Each pixel was on/off. It was entirely 
connected to, and controlled by the H19 terminal's Z80. Firmware was 
provided to draw dots, lines, area fills, etc. with either Cleveland 
Codonic's own command set, or by emulation of the Tektronix 4010 
graphics terminal (which behaved like a plotter; penup, pendown, draw 
from here to there...).

2. Northwest Digital "Graphics Plus GP19"

This board mounted just like the Imaginator, either in the unused CPU 
slot of an H19 or horizontally above the CRT in an H89. It also 
connected exclusively to the H19's terminal logic board.

The Graphics Plus *replaced* the TLB's video RAM with 32k of video RAM. 
The TLB's 6845 CRT controller could be set for different modes of 
operation; character modes were 80x25 (standard), plus 64x32, 80x50, 
132x25, and 132x50. It was amazing to see 132 characters per line and 50 
lines of text on an H19/H89! The graphic modes were 512x250 and 512x500.

The firmware let the H19 emulate 4 terminals; stock Heath/Zenith H19, 
DEC VT-100, ADM-3 (like the Kaypro), and Tektronix 4010. Graphics were 
drawn with either Northwest Digital's own commands, or Tektronix 4010 

3. Northwest Digital "Graphics Plus GP-29"

This was an upgrade intended for the Heath/Zenith H29 terminals, but 
that fit the H19 as well. It *replaced* the H19's TLB, so there was no 
interference with it and an H89 CPU board.

The GP-29 had 64-256k of RAM, and provided all the features of the GP-19 
and then some. The graphic modes could be up to 1024x500 with 4 levels 
of grey scale. With its high resolution and dithering, it could do 
surprisingly good photographic quality displays.

Again, it was entirely controlled via the H19 terminal interface.

4. Sigmasoft & Systems "Integrated Graphics Controller"

This was a series of boards that plugged into an H89's CPU board. Its 
connection to the H89 was via a card that plugged into one of the 
left-side expansion slots on the H89 CPU board. Cables from this board 
connected to several large boards for the graphics, hard disk, floppy 
disk, and other accessories. Some could fit in the H89 case above the 
CPU board as above), or be mounted externally in a separate case.

Besides simply graphics, it could add a hard drive, floppy drives, or 
extra serial or parallel ports. Basically, they provided a second 
terminal in addition to the H19, whose video RAM was accessible directly 
by the H89's CPU board.

The graphics resolution was 640x768, with a 640x250 "window" of it 
appearing on-screen at any given time. It required special software to 
access the graphics and new peripherals, but Sigmasoft was very 
pro-active about writing software to make it all work. They had an 
impressive amount of software to make it do useful things.

5. New Orleans General Data Services

This was a small plug-in I/O board for the H89. It added the video 
controller chip and RAM from a Texas Instruments video game. You needed 
to connect it to an external TV monitor, but then had color graphics and 
sound. I forget the resolution, but it was something like 192x200 in 16 

The main advantage of this board was that it provided flashy displays 
and fast-action graphics. The others were mainly good for high 
resolution still pictures; but this one could have moving airplanes, 
flying bullets, and lots of movement. But software was weak -- you had 
to write such games yourself!

6. TMSI "Superset"

This wasn't a board; it was a new set of chips to install on an H19's or 
H89's Terminal Logic Board. Technically, the TLB still had only 
character graphics; but instead of 128 there were now 1024 characters to 
choose from!

Besides the 33 graphic characters of the H19, you also had the 33 from a 
DEC VT-52, the 128 from an IBM PC, and others. One set provides 
pixel-addressable 160x100 graphics. The Superset also provided VT-100 
text mode commands, moving sprites, an on-screen clock, and other bells 
and whistles.
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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