Xref: utzoo comp.os.os9:286 comp.sys.m6809:970 Path: utzoo!utgpu!watmath!clyde!att!ihlpl!knudsen From: knudsen@ihlpl.ATT.COM (Knudsen) Newsgroups: comp.os.os9,comp.sys.m6809 Subject: Re: MIDI Interface driver for CoCo 3 Summary: COCO-MIDI address; blocking interrupts; religion Keywords: OS-9, Driver, MIDI Message-ID: <7943@ihlpl.ATT.COM> Date: 1 Dec 88 17:14:58 GMT References: <37148@clyde.ATT.COM> <24727@wlbr.EATON.COM> Organization: AT&T Bell Laboratories - Naperville, Illinois Lines: 29 In article <24727@wlbr.EATON.COM>, pete@wlbr.EATON.COM (Pete Lyall) writes: > Kent Meyers and I attempted to adapt an existing 6850 ACIA driver to > work with the COCO MIDI 2 pak (a 6850 UART - I forget the address, but > *think* it's $FF60 or $FF66). It works, but *not* for steady stream The correct address is $FF6E (contro/status) and $FF6F for data. Intercomp Sound's interface pak also uses this address so as to be compatible with all software, and I suggested to Ag that he put his there also. Unforch'ly he uses a 6551. >[discussion of how/when OS9 system blocks interrupts] Well, Pete, it looks like the only way we can record MIDI is to block interrupts ourselves, solid for the duration of the recording, and use our own timing loops to keep time. Alternately, add a FIFO buffer and self-timing counter to the interface a la MPU-401. Burke & Burke are coming out with a clone of this well-known interface and and adapter and driver for it. Funny, isn't it -- the more sophisticated your software (OS9), the more hardware you need to do the same job. (Or is it just overcoming some hardware (MPI, GIME) whose contribution is sometimes negative....?) --mike k -- Mike Knudsen Bell Labs(AT&T) att!ihlpl!knudsen "Lawyers are like nuclear bombs and PClones. Nobody likes them, but the other guy's got one, so I better get one too."