Successful progress report:
Bryanhoop pointed out two coding errors, plus info on the specifics of display screen. This forced me to rearrange my usage of the display's "real estate". Also, it let me proceed to a point that revealed that, for the larger fonts I wanted, I had too many things on the screen, forcing me to reduce my expectations. Result: I've gotten very close to a theme that functions well for me.
Saratoga further discussed the details of the display. This encouraged me to dig deeper on the web. Results:
1. The display is essentially two displays in one.
2. It is up eight 'pages', each 8-pixel 'rows' high, yielding 64 rows of pixels.
3. Two pages (16 rows) at the top of the display, monochrome yellow.
4. Four pages (48 rows) at the bottom of the display, monochrome cyan.
5. Between the top and bottom, there's an unusable black gap.
a. It consumes none of the 64 rows.
b. I think it's there for efficient manufacture of the display.
6. When coding, it's possible to have a viewport that crosses the black bar, but it's distracting (to me, anyway).
To confirm this, I added the following to a .wps:
%pb(2,1,123,4,pb-128x64x1.bmp) # thank you, cabbiev2.wps
%V(2,17,124,1,1)
%xd(b)
%V(2,18,124,1,1)
%xd(b)
The two lines appear on the display.
SO, CASE CLOSED --------------- i think