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Elite on the BBC Micro

Equipment: prx

[BBC Micro cassette version]

Name: prx [Show more] Type: Subroutine Category: Equipment Summary: Return the price of a piece of equipment
Context: See this subroutine in context in the source code Variations: See code variations for this subroutine in the different versions References: This subroutine is called as follows: * EQSHP calls prx * eq calls prx * EQSHP calls entry point prx-3 * eq calls entry point c

This routine returns the price of equipment as listed in the table at PRXS. Arguments: A The item number of the piece of equipment (0-11) as shown in the table at PRXS Returns: (Y X) The item price in Cr * 10 (Y = high byte, X = low byte) Other entry points: prx-3 Return the price of the item with number A - 1 c Contains an RTS
SEC \ Decrement A (for when this routine is called via SBC #1 \ prx-3) .prx ASL A \ Set Y = A * 2, so it can act as an index into the TAY \ PRXS table, which has two bytes per entry LDX PRXS,Y \ Fetch the low byte of the price into X LDA PRXS+1,Y \ Fetch the high byte of the price into A and transfer TAY \ it to X, so the price is now in (Y X) .c RTS \ Return from the subroutine