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software:upi_conventions [2016/06/14 10:18] ex_writer |
software:upi_conventions [2016/06/14 10:25] ex_writer [User-Defined Subroutines] |
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| From system BIOS: | From system BIOS: | ||
| - | <code>The UPI has been extended to support user-supplied routines. If the call index provided is negative [or from $ff through $80] then the users dispatch table pointer (USERTB) is used [also UMARGT]. Note that the sign bit isn't zapped before being used as an index, this means that the users dispatch table pointer should point 128 bytes before the first entry.</code> | + | <code>The UPI has been extended to support user-supplied routines. |
| + | If the call index provided is negative [or from $ff through $80] | ||
| + | then the users dispatch table pointer (USERTB) is used [also UMARGT]. | ||
| + | Note that the sign bit isn't zapped before being used as an index, | ||
| + | this means that the users dispatch table pointer should point | ||
| + | 128 bytes before the first entry.</code> | ||
| Also: | Also: | ||
| Line 146: | Line 151: | ||
| ^ Location ^ Function ^ | ^ Location ^ Function ^ | ||
| - | | 4FFB/4FFC | (Base address of register load specifications) - 40H | | + | | 4FFB/4FFC (UMARGT) | (Base address of register load specifications) - 40H (64D) | |
| - | | 4FFD/4FFE | (Base address of subroutine jump table) - 80H | | + | | 4FFD/4FFE (USERTB) | (Base address of subroutine jump table) - 80H (128D) | |
| The user is responsible for storing the addresses of these tables into dedicated system RAM cells. | The user is responsible for storing the addresses of these tables into dedicated system RAM cells. | ||
