[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: IWM Does Not Exist?
- Subject: Re: IWM Does Not Exist?
- From: "Bryan Parkoff" <nospam@nospam.com>
- Date: Sat, 25 Oct 2003 01:03:38 GMT
- Newsgroups: comp.sys.apple2
- Organization: Road Runner - Texas
- References: <8j1mb.3392$%x5.1644@twister.austin.rr.com> <3f99386d$1_5@corp.newsgroups.com> <M-KdnV97p8KlXgSiRVn-tA@comcast.com>
- Xref: archiver1.google.com comp.sys.apple2:605
Bill,
> Bryan doesn't maybe realize that if you:
>
> LDX #$60
> LDA $C080,X ; actual address being loaded is $C0E0
Well, I already realize that. $C0F0-C0FF is for slot 7. $C0D0-$C0DF is
for slot 5. It is why we are told to use LDX $#50, $#60, or $#70 so IWM can
be mapped to one of 7 slots properly. We are advised not to use LDA $C0x0
because if we move controller card from slot 6 to slot 7, we can change from
LDA $#60 to LDA $#70. We don't have to change from $C0E0-C0EF to
$C0F0-C0FF. It would be easier for us to select slot number rather than
mapping the I/O address. Does it make sense?
If you try to use LDY instead of LDX and LDA $C08x,Y instead of LDA
$C08x,X, it will work either. It is not important.
Bryan Parkoff