84PCE:Ports:0000 - Revision history

MateoConLechuga: /* Bit [6] */

2017-08-06T17:22:56Z

‎Bit [6]

MateoConLechuga: /* Bit [7] */

2017-08-06T17:14:21Z

‎Bit [7]

MateoConLechuga: /* Bit [4] */

2016-05-26T09:45:38Z

‎Bit [4]

Dr. D'nar: /* Bits [1:0] */ I've confirmed that this affects the rate of an interrupt.

2015-08-05T22:14:48Z

‎Bits [1:0]: I've confirmed that this affects the rate of an interrupt.

Dr. D'nar: Created page with "0000 - System Config System Config == Synopsis == '''Port Number:''' 0000 '''Function:''' Controls interr..."

2015-03-27T21:21:48Z

Created page with "0000 - System Config System Config == Synopsis == '''Port Number:''' 0000 '''Function:''' Controls interr..."

New page

[[Category:84PCE:Ports:By_Address|0000 - System Config]] [[Category:84PCE:Ports:By_Name|System Config]]
== Synopsis ==
'''Port Number:''' 0000

'''Function:''' Controls interrupt speed and power

=== Bits [1:0] ===
Changing this changes the cursor blink rate. It's probably some kind of interrupt speed. 11b is slowest, 00b is fastest.

=== Bits [3:2] ===
Writes have no apparent effect, value does not latch.

=== Bit [4] ===
Set this bit to crash.

=== Bit [5] ===
Writes have no apparent effect, value does not latch.

=== Bit [6] ===
Set this bit to turn calc and screen off until next ON key.

=== Bit [7] ===
Latches value written, no apparent effect.

← Older revision		Revision as of 17:14, 6 August 2017
Line 43:		Line 43:

	=== Bit [7] ===		=== Bit [7] ===
−	Latches value written, no apparent effect.	+	Latches value written, no apparent effect. Used when reading battery status.

@@ Line 40: / Line 40: @@
 === Bit [6] ===
-Set this bit to turn calc and screen off until next ON key.
+Set this bit to turn calc and screen off until next ON key. Value does not latch.
 === Bit [7] ===
 Latches value written, no apparent effect. Used when reading battery status.

@@ Line 34: / Line 34: @@
 === Bit [4] ===
-Set this bit to crash.
+Set this bit to crash. The bootcode uses this to crash when catching a non-maskable interrupt.
 === Bit [5] ===

@@ Line 5: / Line 5: @@
 '''Function:''' Controls interrupt speed and power
-=== Bits [1:0] ===
+=== Bits [1:0]: OS Timer Rate ===
-Changing this changes the cursor blink rate. It's probably some kind of interrupt speed. 11b is slowest, 00b is fastest.
+This controls the rate of interrupt source 4, which seems to be some kind of timer. Changing this changes the cursor blink rate. It's probably some kind of interrupt speed. 11b is the slowest, 00b is the fastest. If this is anything like the timers on the Z80 models, its source is the 32768 Hz quartz crystal. A frequency table is below, along with probable divisors if this really is from the 32768 Hz crystal.
 === Bits [3:2] ===