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Schneiderware Pseudo ROM

217 bytes added, 20:09, 30 September 2010
/* I/O Ports */
{|{{Prettytable|width: 700px; font-size: 2em;}}
|Address (default) || Address (alternate) || Usage
|DFxxh || N/A || Schneiderware RAM/EPROM - [[Upper ROM Bank Number|Expansion ROM bank number]] (W)<br>Battery-backed SRAM and/or EPROM are selected when the bank-number matches the jumper-selected values; the memory is then mapped to C000h..FFFFh (in case of READing one must also enable upper ROM via Gate Array). The bank number decoding is a bit strange:
* EPROM/Read bank: All 8 bits decoded (bank 00h..FFh)
* SRAM/Read bank: Only lower 4 bits decoded (bank X0h..XFh)
'''Note''' - Port DFxxh is the standard [[Upper ROM Bank Number]] register, which is also used by AMSDOS, for example. Reserved banks are 00h=Basic, and 07h=AMSDOS. Other bank numbers can be used by one (or more) Schneiderware Pseudo ROM board(s).
== Pictures ==