Difference between revisions of "83Plus:Ports:21"

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'''Note:''' Do not take the information on this template page as actual documentation!
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[[Category:83Plus:Ports:By_Address|21 - Hardware Type]]
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[[Category:83Plus:Ports:By_Name|Hardware Type]]
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The Ports are named by their number, in hexadecimal. An example is [[83Plus:Ports:00]].
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[[Category:83Plus:Ports:By_Address:Protected|21 - Hardware Type]]
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You also must put a variation on the following code into your page to have it categorized:
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NaodW29-nowiki4e456ce16c2fc68b00000001
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----
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== Synopsis ==
 
== Synopsis ==
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'''Port Number:''' 06h
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'''Port Number:''' 21h
  
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'''Function:''' Flash Memory Paging
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'''Function:''' Hardware Type
  
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This port controls what page is swapped into the 4000h to 7FFFh range. ('''DO NOT''' take this template page as real documentation on port 6!)
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This port is simply a protected register which is set by the boot code according to the hardware version.
  
 
=== Read Values ===
 
=== Read Values ===
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* [00h - FFh]: The current port mapped to the memory range 4000h through 7FFFh.
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* Bit 0: 1 on either the 83+ SE or the 84+ SE, 0 on the 84+ basic.
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* Bit 1: ''Unknown -- always set to zero''
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* Bits 2-7 do not seem to do anything.
  
 
=== Write Values ===
 
=== Write Values ===
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* [00h - FFh]: The new page to swap in to the memory range 4000h through 7FFFh
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* [00h - FFh]: New value for the register
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''Note: if you would have bitwise flags for your port, label them "bit X".''
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== Comments ==
 
== Comments ==
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The behavior of this port changes in different memory map modes.
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This port does not exist on the standard 83+.  See [[83Plus:Ports:02|port 2]].
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There is no reason to write to this port, but by reading from it you can determine something about the HW version.
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TIOS polls both bits 0 and 1, by taking the logical AND with 3.
  
 
== Example ==
 
== Example ==
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NaodW29-nowiki4e456ce16c2fc68b00000002
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in a,[[83Plus:Ports:02|(2)]]
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ld b,a
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== Credits and Contributions ==
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and 80h
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* '''/dev/urandom:''' Because of your randomness, this project is possible.
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jr z,TI83p_BE
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in a,(21h)
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and 3
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jr z,TI84p_BE
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bit 5,b
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jr z,TI83p_SE
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; calculator is an 84+ SE
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TI84p_BE:
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; calculator is an 84+ BE
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TI83p_SE:
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; calculator is an 83+ SE
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TI83p_BE:
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; calculator is an 83+ BE

Revision as of 14:17, 29 March 2005

Synopsis

Port Number: 21h

Function: Hardware Type

This port is simply a protected register which is set by the boot code according to the hardware version.

Read Values

  • Bit 0: 1 on either the 83+ SE or the 84+ SE, 0 on the 84+ basic.
  • Bit 1: Unknown -- always set to zero
  • Bits 2-7 do not seem to do anything.

Write Values

  • [00h - FFh]: New value for the register

Comments

This port does not exist on the standard 83+. See port 2.

There is no reason to write to this port, but by reading from it you can determine something about the HW version.

TIOS polls both bits 0 and 1, by taking the logical AND with 3.

Example

	in a,(2)
	ld b,a
	and 80h
	jr z,TI83p_BE
	in a,(21h)
	and 3
	jr z,TI84p_BE
	bit 5,b
	jr z,TI83p_SE
	; calculator is an 84+ SE

TI84p_BE:
	; calculator is an 84+ BE

TI83p_SE:
	; calculator is an 83+ SE

TI83p_BE:
	; calculator is an 83+ BE
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