Difference between revisions of "84PCE:Ports:1002"

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(So bit 3 does do something)
(Bit 3)
(4 intermediate revisions by one other user not shown)
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[[Category:84PCE:Ports:By_Address|1002 - Unknown]] [[Category:84PCE:Ports:By_Name|Unknown port 1005]]
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[[Category:84PCE:Ports:By_Address|1002 - Flash chip size]] [[Category:84PCE:Ports:By_Name|Flash chip size]]
 
== Synopsis ==
 
== Synopsis ==
 
'''Port Number:''' 1002
 
'''Port Number:''' 1002
  
'''Function:''' Unknown. This port definitely doesn't control RAM or flash wait states.
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'''Function:''' Memory-mapped flash chip size.
  
 
== Details ==
 
== Details ==
 
=== Bits [2:0] ===
 
=== Bits [2:0] ===
Some values cause an instant crash unless interrupts are disabled and you are running in a RAM program; if you are running in a RAM program with interrupts disabled, no values cause a crash.
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Sets the flash chip size. 06 is the default (4 MB). 07 will map 8 MB, which will cause the 4 MB to be mirrored twice. Smaller values map less flash, possibly down to 64 K.
 
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{|-
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|<u>Value</u>&nbsp;&nbsp;&nbsp;
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|<u>Effect</u>&nbsp;&nbsp;&nbsp;
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|-
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|0
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|Instant crash
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|-
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|1
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|Instant crash
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|-
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|2
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|Instant freeze
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|-
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|3
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|Crash upon return to OS
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|-
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|4
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|No crash, freezes if you do anything complicated in the OS
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|-
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|5
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|No crash, freezes if you do anything complicated in the OS
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|-
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|6
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|Normal value
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|-
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|7
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|No ill-effects apparent, does not appear to make OS noticeably slower
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|}
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=== Bit 3 ===
 
=== Bit 3 ===
Set this bit to crash.
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When this bit is set, the flash mapping is forced to 64KB (the equivalent of a 0 in bits 0-2).
  
 
=== Bits [7:4] ===
 
=== Bits [7:4] ===
 
Writes have no apparent effect, value does not latch.
 
Writes have no apparent effect, value does not latch.

Revision as of 14:47, 5 April 2015

Synopsis

Port Number: 1002

Function: Memory-mapped flash chip size.

Details

Bits [2:0]

Sets the flash chip size. 06 is the default (4 MB). 07 will map 8 MB, which will cause the 4 MB to be mirrored twice. Smaller values map less flash, possibly down to 64 K.

Bit 3

When this bit is set, the flash mapping is forced to 64KB (the equivalent of a 0 in bits 0-2).

Bits [7:4]

Writes have no apparent effect, value does not latch.