PrismJS · SvOlli · Nov 5, 2025
diff --git a/src/components.json b/src/components.json
@@ -163,6 +163,18 @@
 			"title": "6502 Assembly",
 			"owner": "kzurawel"
 		},
+		"asm65c02": {
+			"title": "65C02 Assembly",
+			"owner": "SvOlli"
+		},
+		"asm65ce02": {
+			"title": "65CE02 Assembly",
+			"owner": "SvOlli"
+		},
+		"asm65816": {
+			"title": "65816 Assembly",
+			"owner": "SvOlli"
+		},
 		"asmatmel": {
 			"title": "Atmel AVR Assembly",
 			"owner": "cerkit"

diff --git a/src/languages/asm65816.js b/src/languages/asm65816.js
@@ -0,0 +1,34 @@
+/** @type {import('../types.d.ts').LanguageProto<'asm65816'>} */
+export default {
+	id: 'asm65816',
+	grammar: {
+		'comment': /;.*/,
+		'directive': {
+			pattern: /\.\w+(?= )/,
+			alias: 'property',
+		},
+		'string': /(["'`])(?:\\.|(?!\1)[^\\\r\n])*\1/,
+		'op-code': {
+			pattern:
+				/\b(?:ADC|AND|ASL|BCC|BCS|BEQ|BIT|BMI|BNE|BPL|BRA|BRK|BRL|BVC|BVS|CLC|CLD|CLI|CLV|CMP|COP|CPX|CPY|DEC|DEX|DEY|EOR|INC|INX|INY|JML|JMP|JSL|JSR|LDA|LDX|LDY|LSR|MVN|MVP|NOP|ORA|PEA|PEI|PER|PHA|PHB|PHD|PHK|PHP|PHX|PHY|PLA|PLB|PLD|PLP|PLX|PLY|REP|ROL|ROR|RTI|RTL|RTS|SBC|SEC|SED|SEI|SEP|STA|STP|STX|STY|STZ|TAX|TAY|TCD|TCS|TDC|TRB|TSB|TSC|TSX|TXA|TXS|TXY|TYA|TYX|WAI|WDM|XBA|XCE|adc|and|asl|bcc|bcs|beq|bit|bmi|bne|bpl|bra|brk|brl|bvc|bvs|clc|cld|cli|clv|cmp|cop|cpx|cpy|dec|dex|dey|eor|inc|inx|iny|jml|jmp|jsl|jsr|lda|ldx|ldy|lsr|mvn|mvp|nop|ora|pea|pei|per|pha|phb|phd|phk|php|phx|phy|pla|plb|pld|plp|plx|ply|rep|rol|ror|rti|rtl|rts|sbc|sec|sed|sei|sep|sta|stp|stx|sty|stz|tax|tay|tcd|tcs|tdc|trb|tsb|tsc|tsx|txa|txs|txy|tya|tyx|wai|wdm|xba|xce)\b/,
+			alias: 'keyword',
+		},
+		'hex-number': {
+			pattern: /#?\$[\da-f]{1,6}\b/i,
+			alias: 'number',
+		},
+		'binary-number': {
+			pattern: /#?%[01]+\b/,
+			alias: 'number',
+		},
+		'decimal-number': {
+			pattern: /#?\b\d+\b/,
+			alias: 'number',
+		},
+		'register': {
+			pattern: /\b[xya]\b/i,
+			alias: 'variable',
+		},
+		'punctuation': /[\[\](),:]/,
+	},
+};
diff --git a/src/languages/asm65c02.js b/src/languages/asm65c02.js
@@ -0,0 +1,34 @@
+/** @type {import('../types.d.ts').LanguageProto<'asm65c02'>} */
+export default {
+	id: 'asm65c02',
+	grammar: {
+		'comment': /;.*/,
+		'directive': {
+			pattern: /\.\w+(?= )/,
+			alias: 'property',
+		},
+		'string': /(["'`])(?:\\.|(?!\1)[^\\\r\n])*\1/,
+		'op-code': {
+			pattern:
+				/\b(?:ADC|AND|ASL|BBR0|BBR1|BBR2|BBR3|BBR4|BBR5|BBR6|BBR7|BBS0|BBS1|BBS2|BBS3|BBS4|BBS5|BBS6|BBS7|BCC|BCS|BEQ|BIT|BMI|BNE|BPL|BRA|BRK|BVC|BVS|CLC|CLD|CLI|CLV|CMP|CPX|CPY|DEC|DEX|DEY|EOR|INC|INX|INY|JMP|JSR|LDA|LDX|LDY|LSR|NOP|ORA|PHA|PHP|PHX|PHY|PLA|PLP|PLX|PLY|RMB0|RMB1|RMB2|RMB3|RMB4|RMB5|RMB6|RMB7|ROL|ROR|RTI|RTS|SBC|SEC|SED|SEI|SMB0|SMB1|SMB2|SMB3|SMB4|SMB5|SMB6|SMB7|STA|STP|STX|STY|STZ|TAX|TAY|TRB|TSB|TSX|TXA|TXS|TYA|WAI|adc|and|asl|bbr0|bbr1|bbr2|bbr3|bbr4|bbr5|bbr6|bbr7|bbs0|bbs1|bbs2|bbs3|bbs4|bbs5|bbs6|bbs7|bcc|bcs|beq|bit|bmi|bne|bpl|bra|brk|bvc|bvs|clc|cld|cli|clv|cmp|cpx|cpy|dec|dex|dey|eor|inc|inx|iny|jmp|jsr|lda|ldx|ldy|lsr|nop|ora|pha|php|phx|phy|pla|plp|plx|ply|rmb0|rmb1|rmb2|rmb3|rmb4|rmb5|rmb6|rmb7|rol|ror|rti|rts|sbc|sec|sed|sei|smb0|smb1|smb2|smb3|smb4|smb5|smb6|smb7|sta|stp|stx|sty|stz|tax|tay|trb|tsb|tsx|txa|txs|tya|wai)\b/,
+			alias: 'keyword',
+		},
+		'hex-number': {
+			pattern: /#?\$[\da-f]{1,4}\b/i,
+			alias: 'number',
+		},
+		'binary-number': {
+			pattern: /#?%[01]+\b/,
+			alias: 'number',
+		},
+		'decimal-number': {
+			pattern: /#?\b\d+\b/,
+			alias: 'number',
+		},
+		'register': {
+			pattern: /\b[xya]\b/i,
+			alias: 'variable',
+		},
+		'punctuation': /[(),:]/,
+	},
+};
diff --git a/src/languages/asm65ce02.js b/src/languages/asm65ce02.js
@@ -0,0 +1,34 @@
+/** @type {import('../types.d.ts').LanguageProto<'asm65ce02'>} */
+export default {
+	id: 'asm65ce02',
+	grammar: {
+		'comment': /;.*/,
+		'directive': {
+			pattern: /\.\w+(?= )/,
+			alias: 'property',
+		},
+		'string': /(["'`])(?:\\.|(?!\1)[^\\\r\n])*\1/,
+		'op-code': {
+			pattern:
+				/\b(?:ADC|AND|ASL|ASR|AUG|BBR0|BBR1|BBR2|BBR3|BBR4|BBR5|BBR6|BBR7|BBS0|BBS1|BBS2|BBS3|BBS4|BBS5|BBS6|BBS7|BCC|BCS|BEQ|BIT|BMI|BNE|BPL|BRA|BRK|BVC|BVS|CLC|CLD|CLE|CLI|CLV|CMP|CPX|CPY|CPZ|DEC|DEW|DEX|DEY|EOR|INC|INW|INX|INY|JMP|JSR|LDA|LDX|LDY|LDZ|LSR|NEG|NOP|ORA|PHA|PHP|PHX|PHY|PHZ|PLA|PLP|PLX|PLY|PLZ|RMB0|RMB1|RMB2|RMB3|RMB4|RMB5|RMB6|RMB7|ROL|ROR|RTI|RTN|RTS|SBC|SEC|SED|SEE|SEI|SMB0|SMB1|SMB2|SMB3|SMB4|SMB5|SMB6|SMB7|STA|STX|STY|STZ|TAB|TAX|TAY|TAZ|TBA|TRB|TSB|TSX|TXA|TXS|TSY|TYA|TYS|TZA|adc|and|asl|asr|aug|bbr0|bbr1|bbr2|bbr3|bbr4|bbr5|bbr6|bbr7|bbs0|bbs1|bbs2|bbs3|bbs4|bbs5|bbs6|bbs7|bcc|bcs|beq|bit|bmi|bne|bpl|bra|brk|bvc|bvs|clc|cld|cle|cli|clv|cmp|cpx|cpy|cpz|dec|dew|dex|dey|eor|inc|inw|inx|iny|jmp|jsr|lda|ldx|ldy|ldz|lsr|neg|nop|ora|pha|php|phx|phy|phz|pla|plp|plx|ply|plz|rmb0|rmb1|rmb2|rmb3|rmb4|rmb5|rmb6|rmb7|rol|ror|rti|rtn|rts|sbc|sec|sed|see|sei|smb0|smb1|smb2|smb3|smb4|smb5|smb6|smb7|sta|stx|sty|stz|tab|tax|tay|taz|tba|trb|tsb|tsx|txa|txs|tsy|tya|tys|tza)\b/,
+			alias: 'keyword',
+		},
+		'hex-number': {
+			pattern: /#?\$[\da-f]{1,4}\b/i,
+			alias: 'number',
+		},
+		'binary-number': {
+			pattern: /#?%[01]+\b/,
+			alias: 'number',
+		},
+		'decimal-number': {
+			pattern: /#?\b\d+\b/,
+			alias: 'number',
+		},
+		'register': {
+			pattern: /\b[xyza]\b/i,
+			alias: 'variable',
+		},
+		'punctuation': /[(),:]/,
+	},
+};
diff --git a/tests/languages/asm65816/comment_feature.test b/tests/languages/asm65816/comment_feature.test
@@ -0,0 +1,13 @@
+;
+; foo bar baz
+
+-------------------------
+
+[
+  ["comment", ";"],
+  ["comment", "; foo bar baz"]
+]
+
+-------------------------
+
+Check for comments
diff --git a/tests/languages/asm65816/directive_feature.test b/tests/languages/asm65816/directive_feature.test
@@ -0,0 +1,12 @@
+.segment CODE
+
+-------------------------
+
+[
+  ["directive", ".segment"],
+  " CODE"
+]
+
+-------------------------
+
+Check for directives
diff --git a/tests/languages/asm65816/number_feature.test b/tests/languages/asm65816/number_feature.test
@@ -0,0 +1,17 @@
+LDA #127
+STA $8000
+STA #$1
+LDX #%10001010
+
+----------------------------------------------------
+
+[
+	["op-code", "LDA"], ["decimal-number", "#127"],
+	["op-code", "STA"], ["hex-number", "$8000"],
+	["op-code", "STA"], ["hex-number", "#$1"],
+	["op-code", "LDX"], ["binary-number", "#%10001010"]
+]
+
+----------------------------------------------------
+
+Check for numbers