prodos-drivers/README.md
Joshua Bell b621ac6a4d Add ROMX RTC driver, c/o Jeff Mazur.
This is a modified version of the ROMX Real-Time Clock driver. The changes include:

* Converting the source to ca65.

* Integrating with the driver installer framework.

* Adapting the driver to not modify page 2 beyond $220. The ROMX RTC
  firmware writes bytes to $2B0, and the the original driver placed
  temp code at $250. This can conflict with ProDOS applications that
  use page 2, so the driver was reworked to save/restore anything at
  at $2B0.

Other changes:

* Add a util/ source dir, and cricket/date, quit.system and
  pause.system there.

* Pull the "print current date" logic out of clock drivers into driver
  preamble.
2021-10-05 19:58:31 -07:00

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# ProDOS Drivers
[![build](https://github.com/a2stuff/prodos-drivers/actions/workflows/main.yml/badge.svg)](https://github.com/a2stuff/prodos-drivers/actions/workflows/main.yml)
Build with [ca65](https://cc65.github.io/doc/ca65.html)
# What are ProDOS "drivers"?
The ProDOS operating system for the Apple II executes the first `.SYSTEM` file found in the boot directory on startup. A common pattern is to have the boot directory contain several "driver" files that customize ProDOS by installing drivers for hardware or modify specific parts of the operating system. These include:
* Real-time Clock drivers (e.g. No-Slot Clock, Cricket!, AE DClock, etc)
* In ProDOS 1.x, 2.0 and 2.4 the Thunderclock driver is built-in.
* RAM Disk drivers (e.g. RamWorks)
* In ProDOS 1.x, 2.0 and 2.4 only a 64K driver for /RAM is built-in.
* Quit dispatcher/selector (`BYE` routines)
* In ProDOS 1.0 and later, a 40-column friendly [selector](selector) prompts for a prefix then a path `ENTER PREFIX (PRESS "RETURN" TO ACCEPT)`
* In ProDOS 1.9 and 2.0.x, on 80-column systems, a menu-driven selector is installed instead.
* In ProDOS 2.4.x [Bitsy Bye](https://prodos8.com/bitsy-bye/) is built-in.
Early versions of these drivers would often invoke a specific file on completion, sometimes user-configurable. The best versions of these drivers simply execute the following `.SYSTEM` file, although this is non-trivial code and often did not work with network drives.
This repository collects several drivers and uses common code to chain to the next `.SYSTEM` file, suporting network drives.
## What is present here?
This repo includes the following drivers/modifications:
* Real-time Clock drivers
* No-Slot Clock
* Cricket!
* Applied Engineering DClock
* ROMX Real-Time Clock
* RAM Disk drivers
* RAMWorks Driver by Glen E. Bredon
* Quit dispatcher/selector (`BYE` routines)
* 40-column Selector (from ProDOS)
* 80-column menu-driven Selector (from ProDOS 1.9 and 2.x)
* Bird's Better Bye (a 40-column menu-driven selector)
* Buh-Bye (an enhanced version of the ProDOS 80-column, menu-driven selector)
In addition, `QUIT.SYSTEM` is present which isn't a driver but which immediately invokes the QUIT handler (a.k.a. program selector). This will happen automatically if the last driver can't find another `.SYSTEM` file, but `QUIT.SYSTEM` can be used to stop the chain.
There's also `PAUSE.SYSTEM` which just waits for a fraction of a second before invoking the next driver file. (Why? In case the log messages from the other installers goes by too fast!)
Non-drivers that are included:
* The `DATE` binary file can be `BRUN` (or just `-DATE`) to show the current ProDOS Date/Time, to verify that the clock driver is working.
* Some utilities for The Cricket! clock are also included.
## How do you use these?
The intent is that you use a tool like Copy II Plus or [Apple II DeskTop](https://github.com/a2stuff/a2d) to copy and arrange the SYSTEM files on your boot disk as you see fit. A boot disk image catalog that is used on multiple different hardware configurations might include:
* `PRODOS` - the operating system, e.g. [ProDOS 2.4](https://prodos8.com/)
* `NS.CLOCK.SYSTEM` - install No-Slot clock driver, if present
* `ROMXRTC.SYSTEM` - install ROMX clock driver, if present
* `DCLOCK.SYSTEM` - install DClock clock driver, if present
* `CRICKET.SYSTEM` - install Cricket! clock driver, if present
* `RAM.DRV.SYSTEM` - install RamWorks RAM disk driver, if present
* `BUHBYE.SYSTEM` - install a customized Quit handler to replace the built-in one
* `PAUSE.SYSTEM` - pause for a moment, so that you can inspect the output of the above
* `QUIT.SYSTEM` - invoke the Quit handler immediately, as a program selector
* `BASIC.SYSTEM` - which will not be automatically invoked, but is available to manually invoke
Alternately, you might want to install some drivers then immediately launch into BASIC. In that case, put `BASIC.SYSTEM` after the drivers in place of `QUIT.SYSTEM`.