From 6454c1d978aafde64e1526aa9ce1afd2ede89e08 Mon Sep 17 00:00:00 2001
From: Joppe Blondel <joppe@joppeb.nl>
Date: Wed, 7 Oct 2026 15:06:03 +0200
Subject: [PATCH] Fixed backspace in basic

---
 Makefile             |  6 +++---
 apps/basic/basic.asm | 31 ++++++++++++++++++++++++-------
 2 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/Makefile b/Makefile
index 5cb1186..8439170 100644
--- a/Makefile
+++ b/Makefile
@@ -25,7 +25,7 @@ $(BUILDDIR)/%.bin: ./%.asm $(BUILDDIR)/memory.inc
 	echo '>$<'
 	$(ASM) $(ASMFLAGS) $< $@
 
-$(BUILDDIR)/basic.bin: $(BUILDDIR)/memory.inc
+basic:
 	$(MAKE) -C apps/basic $(or $(MAKECMDGOALS),all) --no-print-directory
 
 $(BUILDDIR)/memory.inc: memory.mk
@@ -33,7 +33,7 @@ $(BUILDDIR)/memory.inc: memory.mk
 	@awk 'BEGIN { print "; Generated from rom_layout.mk; do not edit." } \
 		/^[A-Z][A-Z0-9_]*[[:space:]]*:=[[:space:]]*/ { print $$1 " .equ " $$3 }' $< > $@
 
-$(BUILDDIR)/rom.bin: $(BUILDDIR)/bios.bin $(BUILDDIR)/basic.bin
+$(BUILDDIR)/rom.bin: $(BUILDDIR)/bios.bin basic
 	echo "bios:   $(shell wc -c < $(BUILDDIR)/bios.bin) / $$(($(BIOS_ROM_SIZE)+0))"
 	echo "basic:  $(shell wc -c < $(BUILDDIR)/basic.bin) / $$(($(BASIC_ROM_SIZE)+0))"
 	objcopy --pad-to=$$(($(BIOS_ROM_START)+$(BIOS_ROM_SIZE))) \
@@ -43,4 +43,4 @@ $(BUILDDIR)/rom.bin: $(BUILDDIR)/bios.bin $(BUILDDIR)/basic.bin
 	cat $(BUILDDIR)/bios_padded.bin $(BUILDDIR)/basic_padded.bin > $(BUILDDIR)/rom.bin
 
 
-.PHONY: $(TOPTARGETS) $(SUBDIRS)
+.PHONY: $(TOPTARGETS) $(SUBDIRS) basic
diff --git a/apps/basic/basic.asm b/apps/basic/basic.asm
index 0a85ae3..9244bbb 100644
--- a/apps/basic/basic.asm
+++ b/apps/basic/basic.asm
@@ -13,6 +13,7 @@
 ;    - fixed ram size instead of poking at ram locations
 ;    - BIOS calls instead of using RST
 ;    - Unsupported functions cause FCERR, not a reset or REM
+;    - modern backspace handling
 ;
 ;==================================================================================
 ; The updates to the original BASIC within this file are copyright Grant Searle
@@ -52,7 +53,7 @@ MC_RAM_END              .EQU    0FFFFH
 
 CTRLC   .EQU    03H             ; Control "C"
 CTRLG   .EQU    07H             ; Control "G"
-BKSP    .EQU    7FH             ; Back space
+BKSP    .EQU    08H             ; Back space
 LF      .EQU    0AH             ; Line feed
 CS      .EQU    0CH             ; Clear screen
 CR      .EQU    0DH             ; Carriage return
@@ -62,7 +63,7 @@ CTRLR   .EQU    12H             ; Control "R"
 CTRLS   .EQU    13H             ; Control "S"
 CTRLU   .EQU    15H             ; Control "U"
 ESC     .EQU    1BH             ; Escape
-DEL     .EQU    08H             ; Delete
+DEL     .EQU    7fH             ; Delete
 
 ; BASIC WORK SPACE LOCATIONS
 
@@ -942,10 +943,25 @@ ECHDEL: DEC     B               ; Count bytes in buffer
         CALL    OUTC            ; Echo it
         JP      MORINP          ; Get more input
 
-DELCHR: DEC     B               ; Count bytes in buffer
-        DEC     HL              ; Back space buffer
-        CALL    OUTC            ; Output character in A
-        JP      NZ,MORINP       ; Not end - Get more
+DELCHR: ;DEC     B               ; Count bytes in buffer
+        ;DEC     HL              ; Back space buffer
+        ;CALL    OUTC            ; Output character in A
+        ;JP      NZ,MORINP       ; Not end - Get more
+        LD      A,B
+        CP      1
+        JP      Z,MORINP
+        DEC     B
+        DEC     HL
+        LD      A,(CURPOS)
+        DEC     A
+        LD      (CURPOS),A
+        LD      A,BKSP
+        CALL    MONOUT
+        LD      A,' '
+        CALL    MONOUT
+        LD      A,BKSP
+        CALL    MONOUT
+        JP      MORINP
 OTKLN:  CALL    OUTC            ; Output character in A
 KILIN:  CALL    PRNTCRLF        ; Output CRLF
         JP      TTYLIN          ; Get line again
@@ -958,7 +974,8 @@ TTYLIN: LD      HL,BUFFER       ; Get a line by character
 MORINP: CALL    CLOTST          ; Get character and test ^O
         LD      C,A             ; Save character in C
         CP      DEL             ; Delete character?
-        JP      Z,DODEL         ; Yes - Process it
+        ;JP      Z,DODEL         ; Yes - Process it
+        JP      Z,DELCHR
         LD      A,(NULFLG)      ; Get null flag
         OR      A               ; Test null flag status
         JP      Z,PROCES        ; Reset - Process character