Tape and RS-232 routines

From: Baltissen, GJPAA (Ruud) <ruud.baltissen_at_apg.nl>
Date: Tue, 14 Aug 2012 12:52:56 +0200
Message-ID: <219DEB1536CDE04E98DDD8620CA8CD68275E44@winsv293.office01.internalcorp.net>
Hallo allemaal,
During a break I went through Data Beckers "C64 Intern" and cam up with this list:
Ranges with tape routines:
$F0D8 - $F105  (messages)
$F179 - $F1B4
$F1DB - $F207
$F2C8 - $F2F0
$F38B - $F3D4
$F539 - $F5AE
$F65F - $F68E
$F72C - $FCE1
$FF43 - $FF47

Disable tape at:
$F38B - OPEN
$F539 - LOAD
$F65F - SAVE
Ranges with RS-232 routines:
$F1B8 - $F1C9
$F208 - $F20D
$F2AB - $F2C7
$F409 - $F49D
$FE72 - $FF42

Disable RS-232 at:
$F177 - BASIN
$F208 - BSOUT
$F227 - CHKIN
$F388 - OPEN
$FE0D - Get status
$FE54 - NMI

You may notice that LOAD and SAVE are missing in the "Disable RS-232 at" list. This is because these functions aren't supported by the C64 anyway. But I wondered why? IMHO it is just a matter of sending and receiving some extra bytes, just as it happens with the IEC bus. Two possible reasons:
- not enough room in the ROM left to implement it.
- people could start using other devices instead of buying Commodore drives ???
André already mentioned using a 16650. Using a real UART means less code needed. The freed space could be used to implement the LOAD and SAVE functions. Just my two cents....

    / __|__
   / /  |_/     Groetjes, Ruud Baltissen
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Received on 2012-08-14 11:00:06

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