External memory interface.
| word | stack | description |
|---|---|---|
| xmem | ( -- ) | enable external memory |
| /xmem | ( -- ) | disable external memory |
| xmem-split | ( x -- ) | configure upper/lower region split |
| xmem-wait-lower | ( x -- ) | configure number of wait states in lower region |
| xmem-wait-upper | ( x -- ) | configure number of wait states in upper region |
| xmem-keep | ( -- bit ) | bus keeper enable bit |
| xmem-mask | ( x -- ) | configure number of masked upper address lines |