Gregory's Server
the 74187 is a 1024-bit ROM (arranged as 256 x 4 bits). i was surprised to see this in my collection since this is a mask ROM device -- typically these have a custom marking on top.
...and yes, there seems to be data in this chip, but it is mostly zeros.
in contrast, the 74LS471 is a 2048 bit PROM (arranged as 256 x 8 bits). looks like i can program it using my Allmax programmer!