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Diffstat (limited to 'ReadMe.TXT')
| -rw-r--r-- | ReadMe.TXT | 49 |
1 files changed, 38 insertions, 11 deletions
@@ -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).
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