Difference between revisions of "84PCE:Ports:5000"
From WikiTI
| Line 81: | Line 81: | ||
|?? | |?? | ||
|''Ports 5013-5020 may always read zero'' | |''Ports 5013-5020 may always read zero'' | ||
| + | |- | ||
| + | |[[:84PCE:Ports:5015|5015]] | ||
| + | |00 | ||
| + | |?? | ||
| + | |Read by the boot code at 001327h after power-off? | ||
|- | |- | ||
|[[:84PCE:Ports:5021|5021]] | |[[:84PCE:Ports:5021|5021]] | ||
Revision as of 00:27, 28 March 2015
This port range has an interesting semi-pattern of read-only and latching ports. A partial list is below, but ports with some kind of function continue until at least 5055.
| Port | Default | Bits | Information |
| 5000 | 00 | ?? | May or may not serve a purpose? |
| 5001 | 80 | ?? | Bit 2 is set while any key is being pressed |
| 5002 | 00 | ?? | Ports 5002-5003 may always read zero |
| 5004 | 11 | FF | Reset bit 4 to freeze |
| 5005 | 30 | FF | Setting bit 2 or bit 7 (or both) will freeze the calculator |
| 5006 | 00 | 3F | Latches value written |
| 5007 | 00 | Ports 5007-500B may always read zero | |
| 500C | 19 | FF | Reset bit 4 to freeze |
| 500D | 00 | FF | Latches value written |
| 500E | 00 | 3F | Latches value written |
| 500F | 00 | Port 500F may always read zero | |
| 5010 | 00 | FF | Latches value written |
| 5011 | 00 | FF | Latches value written |
| 5012 | 00 | 3F | Latches value written |
| 5013 | 00 | ?? | Ports 5013-5020 may always read zero |
| 5015 | 00 | ?? | Read by the boot code at 001327h after power-off? |
| 5021 | 90 | ?? | Bit 3 is set when a key is held |
| 5022 | 08 | ?? | Writes do not change value |
| 5023 | 00 | ?? | Port 5023 may always read zero |
| 5024 | 00 | FF | Latches value written |
| 5025 | 00 | FF | Latches value written |
| 5026 | 00 | 3F | Latches value written |
| 5027 | 00 | ?? | Ports 5027-502B may always read zero |
| 502C | 00 | FF | Latches value written |
| 502D | 00 | FF | Latches value written |
| 502E | 00 | 3F | Latches value written |
