Wiki editing discussion

I did some testing with it

out &h40,8
print inp(&h40)

returns 247 (inverted 8) on FX, WX and WSX. On other tried systems it returns 255

Not if you first get a 2 from 2DH. That will narrow it down to only those three computers.

https://www.msx.org/wiki/Main_Page

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Nope. This will also return 247 on some of the later Sanyo models. Notably the PHC-70FD and PHC-70FD2. There might be others.

	in	a,(40H)
	cpl
	push	af
	ld	a,8
	out	(40H),a		; Factorycode 8 (Panasonic) to I/O port 40h
	in	a,(40H)		; read back value
	cpl			; invert all bits
	cp	8		; if value is not the same
	jr 	nz,NotWx	; Then it's not a FX/WX/WSX
	xor	a		; send 0 to I/O port 41h
	out	(41H),a		; set 5,37MHz mode (1 is go back to 3,57MHz)
NotWX:	pop	af
	out	(40H),a

That routine is good. One should never set expanded I/O ports 41H-4FH without first setting the appropriate device ID to 40H and checking if it is present (reading back the complement), and one should always restore the existing selection after modification (especially on interrupt handlers and hooks).

Although instead of:

	xor	a		; send 0 to I/O port 41h
	out	(41H),a		; set 5,37MHz mode (1 is go back to 3,57MHz)

I would only modify the appropriate bit:

	in	a,(41H)		; get current value of I/O port 41h
	res	0,a		; reset bit 0 (=5.37 MHz) (set for 3,57MHz)
	out	(41H),a		; apply changed value

And yes be aware that although Sanyo MSX2+es do expose the flag, and I think the turboR as well, it’s not hooked up, so (re)setting it has no effect on their CPU speed.