TOSFloppy_2025-04-20T2103-0500.zip2025-04-20

This was the second and final Discord release of the TempleOS floppy
disk controller driver, released April 20, 2025.

This release saw mainly structure changes, plus the addition of a
license file (the code, at this point, is licensed under Do What The
Fuck You Want To Public License, version 2.0).

1 files changed, 38 insertions, 11 deletions

diff --git a/ReadMe.TXT b/ReadMe.TXT
index 9e2970a..2c84cb2 100644
--- a/ReadMe.TXT
+++ b/ReadMe.TXT
@@ -1,21 +1,32 @@
-These files contain the code required for the low-level floppy disk driver.
-Currently, there is no block device code that implements this driver.
+Copyright (c) 2025 Yoshi128k.
+The source code included in this package is licensed under Version 2
+of the Do What The Fuck You Want To Public License; the exact distribution
+terms are described in Copying.TXT.
+The driver and all demonstration software included with this software package comes
+with ABSOLUTELY NO WARRANTY, to the extent permitted by applicable law.
+
 
-System source files from my system are included as a reference.
+
+These files contain the code required for the low-level floppy disk driver.
+Currently, there is no block device code that implements this driver as I
+find it a bit beyond my capabilities.
 
 To install the driver:
-1. Copy Floppy.HC and Floppy.HH to the Kernel directory
-2. Copy the headers at the bottom of the provided KernelC.HC into *your* KernelC.
-3. Add "U8 FDC_DMA[0x4800];" to the bottom of KStart32.HC; This is the DMA buffer for the floppy disk (yeah, I know, DMA = blasphemy, but it's more reliable than PIO while being just as simple).
-4. Add Floppy.HC and Floppy.HH to Kernel.PRJ so that they will be compiled into the kernel.
+1. Copy KFloppy.HC, KFloppyA.HH, KFloppyB.HH, and KFloppyDMA.HC to ::/Kernel/
+2. In Kernel.PRJ(.Z), include KFloppyDMA.HC between KStart32 and KStart64; this adds a
+buffer for DMA transfers to/from the floppy disk controller (see notes)
+3. Then, include KFloppyA.HH and KFloppy.HC at the bottom of the above file.
+4. In ::/StartOS.HC, include KFLoppyB.HH after KernelC.HH; this exports the driver
+functions for use by your own programs.
 
 On startup, you will have to unmask IRQ6 and point its int to the IRQ handler, FDCIrqHandler.
-To do this, write 0xB8 to port 0x21, then use IntEntrySet to set the vector for the aforementioned int.
+To do this, write 0xB8 to port 0x21, then use IntEntrySet to set the vector for the aforementioned int (this may be included in the startup files).
+
 In HolyC, that would be:
-OutU8(0x21,0xB8);
-IntEntrySet(0x26,&FDCIrqHandler,IDTET_IRQ);
+OutU8(0x21,0xB8); // Unmask IRQ6
+IntEntrySet(0x26,&FDCIrqHandler); // IRQ mode is the default
 
-Use FDCReset to initialize the drive (make sure a disk is inserted; it does not test for one before doing things)
+Use FDCReset to initialize the drive (make sure a disk is inserted; it does not test for one before doing things).
 
 FDCSeek does what it says.
 
@@ -25,3 +36,19 @@ Data that has been read or is to be written goes in FDC_DMA.
 (The FDC*Multi funs use multi-track mode; data will be read from both heads)
 
 The result of seeks, recalibrations, and data xfers will be displayed in the Adam Task.
+
+--A note about DMA--
+If things went to plan, I would have use PIO to do data transfers to and from the disk.
+However, they didn't, and my dev system would freeze when attempting to read from tracks
+beyond 0 (the drive would make a seek noise, at which point it froze).
+
+In Terry's demands document, he wrote:
+"We don't want to do DMA."
+
+This is a bit ambiguous, as there are two principle forms of DMA in the PC world:
+
+1. ISA DMA, used by the floppy controller and ISA expansion cards.
+2. PCI Busmastering, which is used by modern hardware and is very different from ISA DMA.
+
+TheTinkerer on the TOS Discord suggested that Terry *may* have been fine ISA DMA, but I would still
+consider my usage of it to be at least a little blasphemous (though it is not mentioned in the Charter).
\ No newline at end of file