Added check VDU 23 char is >=32

2025-01-08 08:30:01 +00:00 · 2022-12-29 16:49:05 -05:00 · 2022-12-29 16:49:05 -05:00 · a0dafe2437
commit a0dafe2437
parent f61c535b5f
2 changed files with 5 additions and 3 deletions
--- a/applecorn.po
+++ b/applecorn.po
--- a/auxmem.shr.s
+++ b/auxmem.shr.s
@ -181,8 +181,10 @@ SHRUSERCHAR   LDA   #<SHRFONTXPLD          ; Use VDUADDR to point to ..
              STA   VDUBANK

              LDA   VDUQ+0                 ; Character number
-              SEC
-              SBC   #32                    ; Font starts at 32
+              CMP   #32                    ; < 32? Then bail out
+              BCC   :DONE
+              SEC                          ; Otherwise, subtract 32
+              SBC   #32
              TAY

              LDA   #16                    ; Bytes/char in 640 mode              
@ -211,7 +213,7 @@ SHRUSERCHAR   LDA   #<SHRFONTXPLD          ; Use VDUADDR to point to ..
              INY
              CPY   #$08                   ; Last row?
              BNE   :L1
-              RTS
+:DONE         RTS
 :INCREMENT    DB    $00