lashtear · November 11, 2025 11:33 · lashtear · Nov 11, 2025 · lashtear · Nov 11, 2025
diff --git a/detect-bare.fs b/detect-bare.fs
 \ Adapted from http://forum.6502.org/viewtopic.php?f=2&t=2263
 \ also cf. http://forum.6502.org/viewtopic.php?f=2&t=5931

 include 816w2.fs
 hex flush

 : output-filename s" detect-sim.bin" ;

 #-514 constant no-such-file
 0fff5 constant SIM_CIN
 0fff6 constant SIM_EOF
 0fff7 constant SIM_ABORT
 0fff8 constant SIM_EXIT
 0fff9 constant SIM_COUT

 output-filename delete-file ?dup [if]
    dup no-such-file <> [if]
        throw [then]
    drop
 [then]

 use detect-sim.bin
 forth also 816asm
 set-emulation
 0 tdp !

 2000 4 - origin!               \ nonsense origin for building the file
 there constant loadaddr-cell   \ tell sim to load at $2000
 2000 t,
 there constant length-cell
 0 t, ( figure it out later )
 there constant entry           \ $2000 entry/origin

 \ detect via the Chromatix method, cf.
 \ http://forum.6502.org/viewtopic.php?f=2&t=5931

 0 lda:#m 84 sta:d 85 sta:d
 1d lda:#m 83 sta:d
 6b lda:#m 1d sta:d
 4e lda:#m

 \ Now we have zeropage set up like
 \ 1d: 6b
 \ 83: 1d
 \ 84: 00
 \ 85: 00
 \ with 4e in the accumulator

 83 eor:dil ( aka 83 rmb4 cmos) \ execute $47 $83, then
 83 eor:d                       \   survey the wreckage

 \ type  | NMOS 6502 | WDC 65c816 | Rockwell 65c02
 \ raw   | 47 83     | 47 83      | 47 83
 \ trad  | SRE ($83) | EOR [$83]  | RMB4 ($83)
 \ ours  | 83 sre:d  | 83 eor:dil | 83 rmb4:d

 \ NMOS - SRE-direct seems to be roughly:
 \    SRE {adr} = LSR {adr}; EOR {adr}
 \ A contains 'N'

 \ 65SC02 sees 47 83 as two nops
 \ A contains 'S'

 \ 65C816 EOR [$83]:
 \    a ^= mem[direct(83) | direct(84)<<8 | direct(85)<<16]
 \ A contains '8'

 \ 65C02 RMB4 ($83):
 \    mem[83] &= !(1<<4)
 \ A contains 'C'

 'N' cmp:#m eq/ if,             \ Quacks like NMOS so far
    cli:. sed:.                \ Check for broken decimal
    90 lda:#m 10 adc:#m
    cld:. sei:. cs/ if,
        'N' lda:#m             \ Decimal works
        rol:. ror:.            \ Check for broken ROR
        cc/ if,
            'O' lda:#m         \ ROR broken!
        then,
    else,
 	'd' lda:#m             \   Decimal missing like 2A03
    then,
 then,

 'S' cmp:#m                     \ Looks like a sc-test but
 there 6 + dup bne:r bra:r      \   branch on fail and always
 'n' lda:#m                     \ Anything reaching here past
                               \   the BNE+BRA is probably a
                               \   bad NMOS simulator doing
                               \   NOPs for undoc insns

 'C' cmp:#m eq/ if,             \ Smells CMOSsy
    1 ldy:#x 1 cpy:#x          \ Setup y=$01, z=1
    ( 8 REP aka CLY,PHP aka 8 CPZ )

    8 rep:#                    \ Try 8 rep.#; on an 816 this
                               \   is just cld:..
    eq/ if,                    \ But z should still be set
        0 cpy:#x eq/ if,       \ If y is zero, we ran CLY,PHP
            ply:.              \   so fix up the stack
            'H' lda:#m         \   and report Hudson
        then,
    else,
        'E' lda:#m             \ We ran 8 CPZ instead, so
    then,                      \   we seem to be a 65CE02
 then,

 '8' cmp:#m eq/ if,             \ Definitely an 816 so turn
    sec:. xce:. cc/ if,        \   on 6502, but native before?
        ply:.                  \   Yes, so fix the stack
    then,
 then,

 \ accumulator now contains ASCII:
 \ O - old NMOS 6502 (faulty ROR)
 \ N - real NMOS 6502
 \ n - NMOS simulator with 1-byte NOPs
 \ d - NMOS without Decimal mode (eg. Ricoh 2A03)
 \ S - 65SC02
 \ C - 65C02
 \ E - 65CE02
 \ H - HuC6280
 \ 8 - 65C816 or 65C802

 SIM_COUT sta:a
 0a lda:#m
 SIM_COUT sta:a
 00 lda:#m
 SIM_EXIT sta:a
 0 brk:#

 \ fixup block load size now that we know it
 there entry - length-cell t!

 \ append a vector block so it knows where to start
 0fffa t,
 6 t,
 2000 t,  \ NMI
 2000 t,  \ Reset
 0fff7 t, \ IRQ/BRK


 cr
 flush

 variable fileid

 output-filename r/w open-file throw fileid !
 there loadaddr-cell - 0 fileid @ resize-file throw
 fileid @ close-file throw

 bye
	\ Adapted from http://forum.6502.org/viewtopic.php?f=2&t=2263
	\ also cf. http://forum.6502.org/viewtopic.php?f=2&t=5931

	include 816w2.fs
	hex flush

	: output-filename s" detect-sim.bin" ;

	#-514 constant no-such-file
	0fff5 constant SIM_CIN
	0fff6 constant SIM_EOF
	0fff7 constant SIM_ABORT
	0fff8 constant SIM_EXIT
	0fff9 constant SIM_COUT

	output-filename delete-file ?dup [if]
	dup no-such-file <> [if]
	throw [then]
	drop
	[then]

	use detect-sim.bin
	forth also 816asm
	set-emulation
	0 tdp !

	2000 4 - origin! \ nonsense origin for building the file
	there constant loadaddr-cell \ tell sim to load at $2000
	2000 t,
	there constant length-cell
	0 t, ( figure it out later )
	there constant entry \ $2000 entry/origin

	\ detect via the Chromatix method, cf.
	\ http://forum.6502.org/viewtopic.php?f=2&t=5931

	0 lda:#m 84 sta:d 85 sta:d
	1d lda:#m 83 sta:d
	6b lda:#m 1d sta:d
	4e lda:#m

	\ Now we have zeropage set up like
	\ 1d: 6b
	\ 83: 1d
	\ 84: 00
	\ 85: 00
	\ with 4e in the accumulator

	83 eor:dil ( aka 83 rmb4 cmos) \ execute $47 $83, then
	83 eor:d \ survey the wreckage

	\ type \| NMOS 6502 \| WDC 65c816 \| Rockwell 65c02
	\ raw \| 47 83 \| 47 83 \| 47 83
	\ trad \| SRE ($83) \| EOR [$83] \| RMB4 ($83)
	\ ours \| 83 sre:d \| 83 eor:dil \| 83 rmb4:d

	\ NMOS - SRE-direct seems to be roughly:
	\ SRE {adr} = LSR {adr}; EOR {adr}
	\ A contains 'N'

	\ 65SC02 sees 47 83 as two nops
	\ A contains 'S'

	\ 65C816 EOR [$83]:
	\ a ^= mem[direct(83) \| direct(84)<<8 \| direct(85)<<16]
	\ A contains '8'

	\ 65C02 RMB4 ($83):
	\ mem[83] &= !(1<<4)
	\ A contains 'C'

	'N' cmp:#m eq/ if, \ Quacks like NMOS so far
	cli:. sed:. \ Check for broken decimal
	90 lda:#m 10 adc:#m
	cld:. sei:. cs/ if,
	'N' lda:#m \ Decimal works
	rol:. ror:. \ Check for broken ROR
	cc/ if,
	'O' lda:#m \ ROR broken!
	then,
	else,
	'd' lda:#m \ Decimal missing like 2A03
	then,
	then,

	'S' cmp:#m \ Looks like a sc-test but
	there 6 + dup bne:r bra:r \ branch on fail and always
	'n' lda:#m \ Anything reaching here past
	\ the BNE+BRA is probably a
	\ bad NMOS simulator doing
	\ NOPs for undoc insns

	'C' cmp:#m eq/ if, \ Smells CMOSsy
	1 ldy:#x 1 cpy:#x \ Setup y=$01, z=1
	( 8 REP aka CLY,PHP aka 8 CPZ )

	8 rep:# \ Try 8 rep.#; on an 816 this
	\ is just cld:..
	eq/ if, \ But z should still be set
	0 cpy:#x eq/ if, \ If y is zero, we ran CLY,PHP
	ply:. \ so fix up the stack
	'H' lda:#m \ and report Hudson
	then,
	else,
	'E' lda:#m \ We ran 8 CPZ instead, so
	then, \ we seem to be a 65CE02
	then,

	'8' cmp:#m eq/ if, \ Definitely an 816 so turn
	sec:. xce:. cc/ if, \ on 6502, but native before?
	ply:. \ Yes, so fix the stack
	then,
	then,

	\ accumulator now contains ASCII:
	\ O - old NMOS 6502 (faulty ROR)
	\ N - real NMOS 6502
	\ n - NMOS simulator with 1-byte NOPs
	\ d - NMOS without Decimal mode (eg. Ricoh 2A03)
	\ S - 65SC02
	\ C - 65C02
	\ E - 65CE02
	\ H - HuC6280
	\ 8 - 65C816 or 65C802

	SIM_COUT sta:a
	0a lda:#m
	SIM_COUT sta:a
	00 lda:#m
	SIM_EXIT sta:a
	0 brk:#

	\ fixup block load size now that we know it
	there entry - length-cell t!

	\ append a vector block so it knows where to start
	0fffa t,
	6 t,
	2000 t, \ NMI
	2000 t, \ Reset
	0fff7 t, \ IRQ/BRK


	cr
	flush

	variable fileid

	output-filename r/w open-file throw fileid !
	there loadaddr-cell - 0 fileid @ resize-file throw
	fileid @ close-file throw

	bye
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