I was watching a video of Dan Ingalls' Seven (give or take) Smalltalk Implementations talk given at Stanford in 2005, and around the 43 minute mark Ingalls mentioned something very interesting:
In 1978, a year after the introduction of the Apple II, Xerox PARC built a portable personal computer with a 7 inch, 640 by 480 pixel resolution bit-mapped, touch-screen display, an Ethernet interface, a 5 MHz, 16-bit 8086 microprocessor, and 128 KiB of memory running Smalltalk-76. The computer was called the NoteTaker.
The NoteTaker ran Smalltalk as fast as the Alto (the Smalltalk-76 VM took up 6 KiB and executed bytecode twice as fast on the 8086 as on the Alto, but the memory bus was much slower, making interactive performance feel similar).
I always assumed the 8086 was very underpowered and good only for DOS and terminals. In hindsight, it is mind-boggling how long it took x86 PCs to catch up with the Macintoshes and Amigas of the 1980s.
The current Wikipedia article about NoteTaker claims the NoteTaker would have cost more than $50,000 if sold commercially (presumably in 1978 dollars). Assume that the CRT, floppy disk, power supply, keyboard and mouse cost $2,000 (a whole Apple II system with 4 KiB memory retailed for $1,298.00 in 1977). The 8086 originally wholesaled for $360. According to the NoteTaker manual, the NoteTaker had a second 8086 which acted as an I/O processor but was "also available for general purpose computing tasks." It would have been possible to replace the I/O processor with a cheaper CPU. Looking again at Apple's price list, a 48 KiB Apple II board retailed for $1,938, while a bare-bones 4 KiB one sold for $598, which gives $31 per KiB. So 128 KiB would retail for $3,900 and 256 KiB would retail for $7,800. It certainly would have been possible to produce and maybe even sell the NoteTaker with 256 KiB of memory for less than $15,000. Note that a few years later, Kim McCall and Larry Tessler made a subset of Smalltalk-76 that ran in 64 KiB of memory, but with the full system image only about 8 KiB of memory was available for user programs.
 Some sources give the NoteTaker's date as 1976, but this is likely the date when design started, as the 8086 design also just started in 1976 and the processor did not ship until 1978. The NoteTaker manual is also dated December, 1978.
 The NoteTaker manual specs the machine at 256 KiB of memory.
While researching this article, I stumbled on two other little-known interesting early personal computers. The Kenbak-1, similar in operation and capabilities to the MITS Altair 8800 (both came with lights, toggle switches, and 256 bytes of memory), was sold via advertisements in Scientific American for $750 in 1971, four years before the Altair. The Datapoint 2200 came out in 1971 and was marketed as a programmable terminal, but was in fact a standalone personal computer.