121 Commits

Author	SHA1	Message	Date
Thomas Harte	3219212f03	A closer inspection of the data sheet seems to suggest that invalid command sequences will post ST0.	2017-08-07 07:35:41 -04:00
Thomas Harte	d90e35e5bd	Added a bunch of comments, and ensured that the data request bit remains set for the entire period that command bytes are accepted.	2017-08-07 07:27:00 -04:00
Thomas Harte	73f8488150	Reaching the end of the usable part of my day, decided to tidy up a little before bed with indentation that reflects a distinction between top-level entry points and mere loops.	2017-08-06 22:14:18 -04:00
Thomas Harte	3853966a1e	Removed formal storage of ST3, as it just seems to be composed live. This may turn out also to be the best way to deal with ST0–2, time will tell. Also took a stab at the error in responding properly to the ROM's intended use of seek might be accepting new commands as replacements for old ones rather than rejecting them. That didn't seem to do the trick.	2017-08-06 22:10:12 -04:00
Thomas Harte	d63893a437	Collapsed implementations of recalibrate and seek, and decided to intend to go for an upward count on steps taken rather than a downward one. But seek continues presently to fail.	2017-08-06 21:52:52 -04:00
Thomas Harte	90c74043f5	Remembered to toggle off RQM between bytes. CAT now works.	2017-08-06 21:21:59 -04:00
Thomas Harte	600445d90a	Made a first attempt to return sector contents.	2017-08-06 20:40:29 -04:00
Thomas Harte	e4b405fd3d	With the ROM now using a read ID to set its expectations, implemented that and fixed FIND/READ_HEADER macros for multiple use. Execution now reaches the unimplemented section of read data.	2017-08-06 20:32:46 -04:00
Thomas Harte	3b7ecbdf0d	Renamed result_ to result_stack_ to emphasis the fact that it goes backwards. Switched meaning of CB so that it is set for the entire command, execution and result phases.	2017-08-06 20:17:12 -04:00
Thomas Harte	01efb645cb	Took a reasonable gamble that the CHRN reported is from internal registers, not from the last-found header.	2017-08-06 19:57:34 -04:00
Thomas Harte	b5ec1f42d5	Started resetting 'busy' when entering the result phase. AMSDOS now complains of a missing disk after failing to find sector 01. My belief is that it should end up asking for C1. So this is not even getting through a failure to find a sector correctly yet.	2017-08-06 19:48:17 -04:00
Thomas Harte	e9972aa0dd	Added respect for the index-hole limit on reading, and an error phase.	2017-08-06 19:25:44 -04:00
Thomas Harte	1c9a744b01	Made an effort to start inspecting ID fields, at least. Discovered that my emulation has somehow stopped proceeding beyond sense interrupt status though. Fix one in that area: adjust ST0 just in time for the sense interrupt status response, as that'll need to specify the drive number properly.	2017-08-06 18:06:20 -04:00
Thomas Harte	e6d4bb29d8	Discovered correct sense interrupt status result if nobody is in the completed seeking state, and switched to it. It's a single 0x80 rather than two bytes.	2017-08-06 15:34:33 -04:00
Thomas Harte	6c5b562d97	Made an attempt at some of the correct seek/recalibrate behaviour: it's now asynchronous from command processing and able to work on up to four drives at once. I just probably am not yet hitting all the status flags I need to hit.	2017-08-06 15:22:07 -04:00
Thomas Harte	a7103f9333	Disks are now communicated to the 8272. Which is able to handle four of them.	2017-08-06 13:24:14 -04:00
Thomas Harte	c12425e141	Added storage for the extended four status registers, and made an attempt at implementing the two most trivial result-phase commands. Am slightly paused momentarily trying to figure out whether seek activity is orthogonal to read/write activity.	2017-08-06 12:55:57 -04:00
Thomas Harte	89f6de1383	Started on a real ugly-implementation coroutine approach, and implemented specify as a fairly trivial first command: it has no result phase, and is the only thing called by AMSDOS as part of the initialisation sequence.	2017-08-06 12:36:18 -04:00
Thomas Harte	29288b690e	Switched disk controllers to be instantiated explicitly in terms of cycles, created an Amstrad-specific subclass of the 8272 to record the direct programmatic availability of all disk motors bundled together, and otherwise adjusted to ensure the thing is clocked and that the motor is enabled and disabled appropriately. The 8272 is also now formally a subclass of the incoming MDM controller.	2017-08-06 09:45:16 -04:00
Thomas Harte	25fd3f7e50	Mildly increased work in here, still primarily oriented towards logging what I actually need to get done.	2017-08-05 22:26:59 -04:00
Thomas Harte	3e984e75b6	Strung up an empty shell that eventually should contain the 8272, and added appropriate IO decoding to the Amstrad.	2017-08-05 19:45:52 -04:00