mirror of
https://github.com/a2stuff/prodos-drivers.git
synced 2024-06-12 22:29:28 +00:00
31 lines
1.3 KiB
Markdown
31 lines
1.3 KiB
Markdown
|
# ProDOS Clock Drivers
|
||
|
|
|
||
|
|
The ProDOS operating system for the Apple II personal computer line natively supports the Thunderclock real-time clock card, but there is a protocol for custom clock drivers to be installed:
|
||
|
|
|
||
|
|
* Check `MACHID` bit 0 to see if a clock is already active; abort if so.
|
||
|
|
* Optional: Probe hardware to determine if the clock is present; abort if not.
|
||
|
|
* Relocate the clock driver to LC bank 1, at the address at `DATETIME`+1
|
||
|
|
* Update `DATETIME` to be a `JMP` instruction.
|
||
|
|
* Optional: Chain to the next `.SYSTEM` file.
|
||
|
|
|
||
|
|
In addition:
|
||
|
|
|
||
|
|
* The clock driver must fit into 125 bytes.
|
||
|
|
* The driver may dirty $200-$207 but other memory must be restored if modified.
|
||
|
|
* When invoked, the clock driver should read the clock hardware and encode the date and time into `DATELO`/`DATEHI` and `TIMELO`/`TIMEHI`.
|
||
|
|
* ProDOS calls the clock driver when `GET_TIME` is called, and on every call (`CREATE`, `RENAME`, etc) that might need the date and time.
|
||
|
|
|
||
|
|
See https://prodos8.com/docs/techref/adding-routines-to-prodos/ for more information.
|
||
|
|
|
||
|
|
## Included drivers
|
||
|
|
|
||
|
|
This directory includes drivers for the following real-time clocks:
|
||
|
|
|
||
|
|
* No-Slot Clock
|
||
|
|
* Cricket!
|
||
|
|
* Applied Engineering DClock
|
||
|
|
* ROMX Real-Time Clock
|
||
|
|
* FujiNet Clock
|
||
|
|
|
||
|
|
All follow the above protocol: install only if there is not already a clock, probe for the clock before installing, and chain to the next driver.
|