On Aug 30, 2016, at 2:58 PM, Mattis Lind
<mattislind at gmail.com> wrote:
  ... 
 There are 256 k chips (Intel & TI)  available from a Swedish surplus
 seller. Similar type of chips show up on Ebay as well, for example this
 listing 
http://www.ebay.com/itm/111748975992 
Another possibility would be a current (not surplus) DRAM device such as a 1M x 16 chip,
plus a couple of level shifters to go between the 3.3 V it likes and the 5V logic of the
Pro.
        paul