My first Apple product grew out of developing instruments based on Ohio Scientific computers, which used the same processor as the Apple II. I did prototyping with a Rockwell AIM-65 which also used the 65C02. This card has an AMD 9511 math coprocessor to speed up integer and floating point math by a factor of nearly 100. It was advertised in Physics Today (I know, weird choice) and came with a scientific Forth programming system. I have one still working and it is the slower of the two options offered. The chip was over $150 in 1979. I was so new to design for the amazingly clever Apple II that there are at least two chips that were not needed.
Next was image capture with a long range goal of astronomy products for research. This is a slow scan capture card useful for video of a still image. It captured one column of pixels for each vertical sweep of a video signal. Display was by looking at slices of the gray scale data in hi-res graphics mode.
Paul Baker from Apple and IAI partnered with me when I got the video capture working. To get some cash flow with a simple product he drew up an 80 column card we could sell quite a bit cheaper than Apple's.
The ImageWorks II was a breakthrough. I found that (or Paul suggested trying) my grayscale video output could be combined with the Apple IIe or //gs video with perfect alignment. This gave a great picture with 256 levels of gray and what amounted to a ninth bit for annotation and mouse, etc. It was cheaper to make my own video rate D/A converter for output using a CMOS latch and R/2R network seen in the lower left. The empty sockets accept video rate A/D converters for image capture. The inner socket fit a 6 bit converter and the outer fit a much more expensive 8 bit converter. Remember, 15 MHz bandwidth converters were rather expensive in the mid 80's. The color coding is the way I labeled PALs instead of part numbers. The black vertical sockets accepts a color output adapter with 5 bits each in RGB and a programmable pallet.
There was considerable interest in this very low cost entry to image processing. Researchers in Italy and Greece became repeat customers. One company had a standing order for their electron microscope control and analysis system. Sky and Telescope ran an article by a professor using several for astronomy classes with stored images and at the telescope. Coincidentally, about the time I was planning CCD camera products, an English company began advertising in Sky and Telescope with an astronomy software product called "Redshift". They refused to change the name or buy it from me. Perhaps they new I didn't have the resources to go to court. It certainly seemed so from their dismissive letters. S&T refused to turn down their ads despite having just published the article with my Redshift Limited corporate name all over it. I became caught up in Defense Department work and dropped the other projects for a while. However, as an educator I have been able to (and continue to) save many people from the mistake of buying from a company with such questionable business ethics.
Here is an ImageWorks II with color adapter. Note that in production, I switched the sockets to the back side for a better fit in Slot 7. I built them both ways due to a regular customer who had Apples so loaded that they only fit one way. If you run across an Apple II with a Dapple Systems sticker on it, check for accelerators and ImageWorks cards.