Difference between revisions of "84PCE:Ports:Control"
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If a port is not listed; it indicates that writes have no effect and do not latch, and that reads are 0. Note that this may not be true one hundred percent. | If a port is not listed; it indicates that writes have no effect and do not latch, and that reads are 0. Note that this may not be true one hundred percent. | ||
| + | |||
| + | == Port Address Space == | ||
{|- | {|- | ||
| Line 78: | Line 80: | ||
|80 | |80 | ||
|Cannot change value | |Cannot change value | ||
| + | |- | ||
| + | |[[:84PCE:Ports:001D|001D]] | ||
| + | |A7 | ||
| + | |Privileged address | ||
| + | |- | ||
| + | |[[:84PCE:Ports:0020|0020]] | ||
| + | |7C | ||
| + | |Memory protection | ||
|- | |- | ||
|[[:84PCE:Ports:0028|0028]] | |[[:84PCE:Ports:0028|0028]] | ||
Revision as of 03:25, 6 August 2017
Synopsis
Port Number: 0000-0fff
Function: Master Control
This port range is used to configure and control important things; possibly the reason why it does not have a memory-mapped address.
If a port is not listed; it indicates that writes have no effect and do not latch, and that reads are 0. Note that this may not be true one hundred percent.
Port Address Space
| Port | Default | Information |
| 0000 | 03 | CPU Speed Control |
| 0001 | 03 | OS Timer Control |
| 0002 | Read only, value can change | |
| 0003 | 00 | Hardware ID |
| 0005 | 76 | Set bit 5 to freeze, bit 6 affects backlight |
| 0006 | 03 | Display refresh |
| 0007 | B7 | Latches values written |
| 0008 | 7F | Cannot change value |
| 0009 | 37 | Power control system |
| 000A | FD | Latches value written |
| 000B | F8 | Charging Status |
| 000C | 00 | Latches value written |
| 000D | FF | Bit 0: Freeze if reset Bit 1: Crash if reset Bit 2: No apparent effect if reset Bit 3: Reset to disable VRAM? Upon set, VRAM is garbage. Bits [7:4]Possibly last value written |
| 000E | 0A | Latches value written |
| 000F | 42 | High nibble may be a status, low 2 bits latch value written |
| 001C | 80 | Cannot change value |
| 001D | A7 | Privileged address |
| 0020 | 7C | Memory protection |
| 0028 | Bit 1 is always 0, other bits latch value written | |
| 0029 | 00 | Bit 0 latches value written |
| 002A | 70 | Latches value written |
| 002B | FE | Latches value written |
| 002C | Ports 002C-0031 latch value written | |
| 0032 | Latches value written | |
| 0033 | Latches value written | |
| 0034 | Latches value written | |
| 0035 | Latches value written | |
| 0036 | Ports 0036-0039 latch value written |
