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==Paging== | ==Paging== | ||
The memory space is divided into four 16k pages and can be used in two ways; "Standard paging mode" and "Special paging mode". | The memory space is divided into four 16k pages and can be used in two ways; "Standard paging mode" and "Special paging mode". | ||
Paging is controlled by performing I/O writes to ports 0x1ffd and 0x7ffd. | |||
The bits are described in the table below: | |||
{| class="wikitable" style="text-align: center;" | |||
|- | |||
! rowspan="2" style="width: 5em;" | Port | |||
! colspan="8" | Bit | |||
|- | |||
! style="width: 5em;" | 7 | |||
! style="width: 5em;" | 6 | |||
! style="width: 5em;" | 5 | |||
! style="width: 5em;" | 4 | |||
! style="width: 5em;" | 3 | |||
! style="width: 5em;" | 2 | |||
! style="width: 5em;" | 1 | |||
! style="width: 5em;" | 0 | |||
|- | |||
! rowspan="2" style="height: 5em;" | 0x1ffd | |||
| rowspan="2" | || rowspan="2" | || rowspan="2" | | |||
| rowspan="2" | Printer Strobe | |||
| rowspan="2" | Disk Motor | |||
| ROM high || || 0 | |||
|- | |||
| colspan="2" | Special paging || 1 | |||
|- | |||
! style="height: 5em;" | 0x7ffd | |||
| || || Disable Paging || ROM low || Active Screen || colspan="3" | RAM Bank | |||
|} | |||
====Standard paging mode==== | ====Standard paging mode==== |