|  251 characters long lines instead of 88 | | Title: | 251 characters long lines instead of 88 | | Category: | Utility/Programming | | Release Date: | 2021-02-10 | | Language: | English | | Size: | 64K | | Machine: | PAL & NTSC | | Code Type: | Machine code | | Distribution: | Freeware | | Code by: | RoePipi | | Notes: | |
User Rating: 7/10 (2 votes)
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| | Description | This utility relocates the 88-byte input buffer from $0200-$0258 to $7F00-$7FFB, extending it to 251 bytes (the maximum possible while keeping system integrity). ROM is copied to RAM starting from $8000 and modified accordingly. This is why the 64K requirement. Note that modifying the address space of the input buffer is not possible through RAM vectors because most important values are hard-coded into ROM. The original input routine doesn't even handle values greater than 127 because of depending on the negative flag - fixed.
BASIC programs created with this utility work without problems on original systems, you cannot edit long lines though.
Workflow:
$1200 disable interrupt
$1201 copy $8000-$FCFF from ROM to RAM
$121A copy $FF40-$FFFF from ROM to RAM
$122B disable switching to ROM
$123C copy 'end of RAM' signature before $4000 (or $7F00 optionally)
$1247 switch memtop from $7F to $7E
$1255 fill new input buffer with 00s
$125E switch input buffer from $0200 to $7F00
$127B set input buffer size to 251 chars
$1280 repair tokenizer for 128+ chars lines
$128F init NMI (reset to new settings) |
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