Difference between revisions of "84PCE:Ports:0000"
From WikiTI
(Created page with "0000 - System Config System Config == Synopsis == '''Port Number:''' 0000 '''Function:''' Controls interr...") |
(→Bits [1:0]: I've confirmed that this affects the rate of an interrupt.) |
||
| Line 5: | Line 5: | ||
'''Function:''' Controls interrupt speed and power | '''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. |
| + | {|- | ||
| + | |<u>Value</u> | ||
| + | |<u>Rate (Hz)</u> | ||
| + | |<u>Probable Divisor</u> | ||
| + | |- | ||
| + | |00 | ||
| + | |~442.81 | ||
| + | |32768/74 | ||
| + | |- | ||
| + | |01 | ||
| + | |~212.78 | ||
| + | |32768/154 | ||
| + | |- | ||
| + | |02 | ||
| + | |~150.31 | ||
| + | |32768/218 | ||
| + | |- | ||
| + | |03 | ||
| + | |~104.36 | ||
| + | |32768/314 | ||
| + | |- | ||
| + | |} | ||
=== Bits [3:2] === | === Bits [3:2] === | ||
Revision as of 14:14, 5 August 2015
Contents
Synopsis
Port Number: 0000
Function: Controls interrupt speed and power
Bits [1:0]: OS Timer Rate
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.
| Value | Rate (Hz) | Probable Divisor |
| 00 | ~442.81 | 32768/74 |
| 01 | ~212.78 | 32768/154 |
| 02 | ~150.31 | 32768/218 |
| 03 | ~104.36 | 32768/314 |
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.
