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Programmable I/O Port: Difference between revisions
From SnesLab
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The 8-bit '''Programmable I/O Port''' allows the [[5A22]] to communicate with SNES peripherals. | The 8-bit '''Programmable I/O Port''' allows the [[5A22]] to communicate with SNES peripherals. | ||
There is the register commonly referred to as '''WRIO''' for short located at 4201h. It has [http://www.learningaboutelectronics.com/Articles/Open-collector-output.php open collector output].<sup>[2]</sup> WRIO is the out-port. | There is the register commonly referred to as '''WRIO''' for short located at 4201h. Only the top two bits are used by the [[control deck]]. It has [http://www.learningaboutelectronics.com/Articles/Open-collector-output.php open collector output] and is initialized to FFh on reset.<sup>[2]</sup> WRIO is the out-port. The last sentence of page 2-14-1 likely has a typo; supposed to be referring to page 2-28-1 not 1-28-1. | ||
There is also the RDIO register at 4213h. Only the top two bits are used by the | There is also the RDIO register at 4213h. Only the top two bits are used by the control deck. RDIO is the in-port. | ||
=== See Also === | === See Also === | ||
* [[3D Glass]] | * [[3D Glass]] | ||
* [[X-Band Keyboard]] | * [[X-Band Keyboard]] | ||
* [[External Latch]] | |||
=== References === | === References === | ||
Latest revision as of 04:21, 20 December 2023
The 8-bit Programmable I/O Port allows the 5A22 to communicate with SNES peripherals.
There is the register commonly referred to as WRIO for short located at 4201h. Only the top two bits are used by the control deck. It has open collector output and is initialized to FFh on reset.[2] WRIO is the out-port. The last sentence of page 2-14-1 likely has a typo; supposed to be referring to page 2-28-1 not 1-28-1.
There is also the RDIO register at 4213h. Only the top two bits are used by the control deck. RDIO is the in-port.
See Also
References
- Official Super Nintendo development manual on the programmable i/o port: Page 2-14-1 of Book I
- https://problemkaputt.de/fullsnes.htm#snescontrollersioportsmanualreading
- page 2-28-1 of Book I on WRIO
- page 2-28-7 of Book I on RDIO