84PCE:Ports:1002 - Revision history

Dr. D'nar: Notice of applicability

2020-04-18T15:22:50Z

Notice of applicability

Calc84maniac: /* Bit 3 */

2015-04-05T21:47:34Z

‎Bit 3

Dr. D'nar at 20:34, 5 April 2015

2015-04-05T20:34:13Z

Dr. D'nar: Fixed category name

2015-04-05T20:27:04Z

Fixed category name

Dr. D'nar: So now we know this is the flash chip size.

2015-04-05T19:58:29Z

So now we know this is the flash chip size.

Dr. D'nar at 19:58, 5 April 2015

2015-04-05T19:58:10Z

Dr. D'nar: So bit 3 does do something

2015-04-03T17:26:38Z

So bit 3 does do something

Dr. D'nar at 08:12, 3 April 2015

2015-04-03T08:12:27Z

Dr. D'nar: Created page with "1002 - Flash Wait States? Flash Wait States? == Synopsis == '''Port Number:''' 1002 '''Function:''' Possi..."

2015-03-27T21:38:32Z

Created page with "1002 - Flash Wait States? Flash Wait States? == Synopsis == '''Port Number:''' 1002 '''Function:''' Possi..."

New page

[[Category:84PCE:Ports:By_Address|1002 - Flash Wait States?]] [[Category:84PCE:Ports:By_Name|Flash Wait States?]]
== Synopsis ==
'''Port Number:''' 1002

'''Function:''' Possibly controls flash wait states.

== Details ==
=== Bits [2:0] ===
Possibly controls flash wait states. 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.

{|-
|<u>Value</u>   
|<u>Effect</u>   
|-
|0
|Instant crash
|-
|1
|Instant crash
|-
|2
|Instant freeze
|-
|3
|Crash upon return to OS
|-
|4
|No crash, freezes if you do anything complicated in the OS
|-
|5
|No crash, freezes if you do anything complicated in the OS
|-
|6
|Normal value
|-
|7
|No ill-effects apparent, does not appear to make OS noticeably slower
|}

=== Bits [7:3] ===
Writes have no apparent effect, value does not latch.

@@ Line 3: / Line 3: @@
 '''Port Number:''' 1002
-'''Function:''' Memory-mapped flash chip size.
+'''Function:''' Memory-mapped flash chip size. This port is only applicable to older devices which feature a [[84PCE:Ports:1000|parallel flash chip.]]
 == Details ==

@@ Line 10: / Line 10: @@
 === Bit 3 ===
-Set this bit to crash. Does not appear to change amount of flash mapped.
+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.

@@ Line 6: / Line 6: @@
 == Details ==
-=== Bits [3:0] ===
+=== 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. 08 will attempt to map 16 MB, which has unknown effects but generally causes an instant crash. Smaller values map less flash, and will generally cause the OS to eventually freeze or crash.
+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.
 === Bits [7:4] ===
 Writes have no apparent effect, value does not latch.

@@ Line 1: / Line 1: @@
-[[Category:84PCE:Ports:By_Address|1002 - Unknown]] [[Category:84PCE:Ports:By_Name|Unknown port 1002]]
+[[Category:84PCE:Ports:By_Address|1002 - Flash chip size]] [[Category:84PCE:Ports:By_Name|Flash chip size]]
 == Synopsis ==
 '''Port Number:''' 1002

@@ Line 1: / Line 1: @@
-[[Category:84PCE:Ports:By_Address|1002 - Unknown]] [[Category:84PCE:Ports:By_Name|Unknown port 1005]]
+[[Category:84PCE:Ports:By_Address|1002 - Unknown]] [[Category:84PCE:Ports:By_Name|Unknown port 1002]]
 == Synopsis ==
 '''Port Number:''' 1002

@@ Line 3: / Line 3: @@
 '''Port Number:''' 1002
-'''Function:''' Unknown. This port definitely doesn't control RAM or flash wait states.
+'''Function:''' Memory-mapped flash chip size.
 == Details ==
-=== Bits [2:0] ===
+=== Bits [3:0] ===
-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.
+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. 08 will attempt to map 16 MB, which has unknown effects but generally causes an instant crash. Smaller values map less flash, and will generally cause the OS to eventually freeze or crash.
-−
-{|-
-|<u>Value</u>&nbsp;&nbsp;&nbsp;
-|<u>Effect</u>&nbsp;&nbsp;&nbsp;
-|-
-|0
-|Instant crash
-|-
-|1
-|Instant crash
-|-
-|2
-|Instant freeze
-|-
-|3
-|Crash upon return to OS
-|-
-|4
-|No crash, freezes if you do anything complicated in the OS
-|-
-|5
-|No crash, freezes if you do anything complicated in the OS
-|-
-|6
-|Normal value
-|-
-|7
-|No ill-effects apparent, does not appear to make OS noticeably slower
-|}
-−
-=== Bit 3 ===
-Set this bit to crash.
 === Bits [7:4] ===
 Writes have no apparent effect, value does not latch.