Z80 CPU NMOS or CMOS

Started by arnoldemu, 15:43, 06 January 16

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arnoldemu

I believe almost all CPCs use NMOS cpus.

NMOS:

OUT (C),0
LD A,R/LD A,I -> P/V flag is cleared if interrupt is received during the execution of these commands.

CMOS:

OUT (C),0 actually does OUT (C),255
LD A,R/LD A,I -> no bug

I tested the Z80 in my GX4000 and CPCs and all are NMOS. Are there any CPCs with CMOS Z80's?

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gerald

Quote from: arnoldemu on 15:43, 06 January 16
I believe almost all CPCs use NMOS cpus.

NMOS:

OUT (C),0
LD A,R/LD A,I -> P/V flag is cleared if interrupt is received during the execution of these commands.

CMOS:

OUT (C),0 actually does OUT (C),255
LD A,R/LD A,I -> no bug

I tested the Z80 in my GX4000 and CPCs and all are NMOS. Are there any CPCs with CMOS Z80's?
I do not think Amstrad ever used a CMOS Z80.
Even on the later Plus/GX4000, it's a NMOS Z8400 (CMOS would be Z84C00)

TotO

Using a CMOS Z80 into a CPC will cause some programs failure.
For example, STarKos will not work!
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

TFM

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arnoldemu

Quote from: TFM on 18:46, 06 January 16
Why this?
Programs which use "OUT (C),0" will not work on CMOS. It doesn't out 0, it outs 255!
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TFM

Quote from: arnoldemu on 19:35, 06 January 16
Programs which use "OUT (C),0" will not work on CMOS. It doesn't out 0, it outs 255!


Oh crap! I didn't know! But this can be used to test the CPU version then, right? OUT to a port which you can read again, PSG port f.e. On the other hand if nobody uses CMOS why to bother? But good to know. Thanks for your valuable insights Sir!  :) :)
TFM of FutureSoft
Also visit the CPC and Plus users favorite OS: FutureOS - The Revolution on CPC6128 and 6128Plus

arnoldemu

Quote from: TFM on 19:46, 06 January 16

Oh crap! I didn't know! But this can be used to test the CPU version then, right? OUT to a port which you can read again, PSG port f.e. On the other hand if nobody uses CMOS why to bother? But good to know. Thanks for your valuable insights Sir!  :) :)
correct.
But I think nobody uses cmos.


My games. My Games
My website with coding examples: Unofficial Amstrad WWW Resource

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