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## 8. Limitations

## 8.1 DOS 3.3

Although the standard binaries generated by the linker for the enhanced Apple //e generally run both on DOS 3.3 (with Applesoft BASIC) and on ProDOS 8 (with BASIC.SYSTEM) there are some limitations for DOS 3.3:

Disk File I/O

  There's no disk file I/O support. Any attempt to use it yields an error with `errno` set to `ENOSYS`. This implicitly means that loadable drivers are in general not functional as they depend on disk file I/O. However they may be converted to statically linked drivers using the co65 object-file converter.

Interrupts

  There's no `interruptor` support. Any attempt to use it yields the message 'Failed to alloc interrupt' on program startup. This implicitly means that `a2e.stdmou.mou` and `a2e.ssc.ser` are not functional as they depend on interrupts.

## 8.2 DIO

Although DIO generally works with all ProDOS 8 devices, the function dio_query_sectcount() simply always return 280 (which is only correct for a 140 KB disk).

## 8.3 Direct console I/O

Color

  The enhanced Apple //e has no color text mode. Therefore the functions textcolor(), bgcolor() and bordercolor() have no effect.

Cursor

  The enhanced Apple //e has no hardware cursor. Therefore the function cursor() has no effect.

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