SYMBiFACE II:Rewriteable roms
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This article decribes, how to map the rewriteable ROMs of the SYMBiFACE II card into the ram area so that you can change its content.
The re-writeable ROMs are stored on a static RAM. The static RAM is powered by a CR2032 battery to remember it's contents when the symbiface 2 is powered down.
Mechanisms
Please note, that the following commands ignore all values. So it doesn't matter, what you "out". When you "inp" you won't get any meaningful numbers.
| INP &FD17 | show the current ROM (selected by #df00) between #4000 and #7fff. Now it can be read and rewritten. You do not need to enable the upper rom using port #7fxx and all roms can be read/written regardless of J2 state or rom enable/disable state. |
| OUT &FD17 | disable the previouse mentioned ROM write mode. |
| OUT &FD11 | disable all SYMBiFACE II Roms. You won't see any additional ROMS anymore, only the CPCs' inbuilt ones. |
| INP &FD11 | enable the SYMBiFACE II roms. |
