I thought the machine I have is an Apple II. Then I thought it was an Apple II with updated II+ ROMs. Now I don't know.
The machine boots up (thanks for all the suggestions!!) with "Apple ][" on the display and a "]" prompt. This an Applesoft BASIC prompt, not Integer BASIC. That is what I'd expect on a II+. I naively tried the various keyboard tricks of escaping/switching to INT Basic- no go.
What do I look for to determine if this is a II motherboard with II+ ROMs, or really a II+?
What else I know:
** It ain't a Rev 0 board (based on http://www.willegal.net/appleii/appleii-first_page.htm )
** The center of motherboard has a "1978" printed below the "apple computer inc" text.
** The board has a hand-marked as 7928 (serial number?) in the corner near the power connector.
** In Apple's Model number scheme, A2S0xxxx is a II, A2S1xxxx is a II+, right?
** The case sticker has a X-mark next to "A2S0016" (So it's a II ??)
** The same case sticker gives a serial number of "A2S1-61847" (So it's a II+ ??)
** In locations D1, E1, F1 (where it says "Memory Select") it has the 3 chips/plug-in-things on each is printed "16K 16K 16K"
** The ROMs have manufacture dates of 1978 (if I read them correctly).