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Toni Wilen · 19 September 2020, 08:14

AmigaOS never uses it but there was at least one game (I don't remember which one) that sets M-bit and requires working MSP.

One possibility is that some game uses ISP instead of A7 to modify (or read) supervisor stack pointer. (if ISP is not implemented). ISP == supervisor stack pointer if M=0.

19 September 2020, 08:14	#67
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,532	AmigaOS never uses it but there was at least one game (I don't remember which one) that sets M-bit and requires working MSP. One possibility is that some game uses ISP instead of A7 to modify (or read) supervisor stack pointer. (if ISP is not implemented). ISP == supervisor stack pointer if M=0.