The original Apple I didn't use RAM to hold the contents of the display, but instead used a group of six 1024-bit shift registers to hold the display contents and a seventh 1024-bit shift register to keep track of the cursor position. The normal means of outputting data to the display was to somehow activate a signal that would cause the display to store a byte into the display shifters at the spot where the "cursor" shifter had a 1, and then bump the cursor shifter by a space. This approach was limited to outputting one character per frame.
On the other hand, there are some other approaches which seem able to write more data on a frame. For example, when scrolling the screen, the system seems to be able to clear all 40 of the "new" characters on a single frame, and when clearing the screen it appears to be able to write all 960 characters and then set the single bit in the cursor shift register associated with the upper-left corner of the screen.
Did the Apple I provide any means, or could it be readily modified to provide any means, by which the CPU could manipulate the cursor shifter or force a character into the shift register at whatever part in the cycle it happened to be, allowing suitably-written code to produce faster screen output? If one could e.g. cause 1 bits to be stored into every ninth bit of the cursor shifter, it would seem like it should be possible to write any number of lines of text in nine frames by waiting for display scanning to reach the first line to be written, outputting one useful byte of data every nine cycles, waiting for the next line, outputting one useful byte of data every nine cycles, etc. and then cancel the "write-character" operation once all lines of interest had been written? Do any emulators or recreations of the Apple I support such things?
While being able to simply store screen contents in RAM as was done on the Apple ][ was better than anything that could have been done using shift registers, I would think that the shift-register-based design of the Apple I could have been used much more effectively than it was had it not been so quickly obsoleted.