Apple-2-SW/prodos-drivers
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v1.7
prodos-drivers/clocks
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Joshua Bell 537d79810b Jumbo: Patch ThunderClock driver for 2023-2028 
If ProDOS finds a ThunderClock it installs a built-in driver for it.
The ThunderClock card gives day-of-week but not year. So the driver
uses the day/month/day-of-week to infer the year, using a 7-entry
table. This means the driver gives the wrong year unless it is
reasonably updated.

ProDOS 2.4.2 includes an update to handle 2018-2023 but that's about
to run out. https://github.com/ProDOS-8/ProDOS8-Testing/issues/72

Make the CLOCK.SYSTEM jumbo driver do the extra work of updating the
year table for the ThunderClock driver. This handles old versions of
ProDOS from 1.1 through 2.4.2, and the update handles 2023 through
2028. (In 2027 we can update again to handle through 2032.)
2023-12-04 20:28:25 -08:00
..
cricket Build: Use common out/ dir 2023-11-12 16:42:11 -08:00
dclock Build: Use common out/ dir 2023-11-12 16:42:11 -08:00
fujinet Build: Use common out/ dir 2023-11-12 16:42:11 -08:00
jumbo Jumbo: Patch ThunderClock driver for 2023-2028 2023-12-04 20:28:25 -08:00
ns.clock Build: Use common out/ dir 2023-11-12 16:42:11 -08:00
romx Build: Use common out/ dir 2023-11-12 16:42:11 -08:00
Makefile Add build options to suppress success and/or failure logging 2023-05-01 19:47:10 -07:00
README.md Add "jumbo" clock driver, an amalgamation of the others 2022-11-26 20:29:38 -08:00

README.md

ProDOS Clock Drivers

Other than the Apple IIgs model, the Apple II did not ship with a real-time system clock. Many third party Apple II system clocks were produced in the 1980s, and many new system clocks are available, either as entirely new designs or recreations.

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:

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.

In addition, the "jumbo" directory combines the other driver installers to create a single unified clock driver installer. See its README for more details.