> On Apr 20, 2016, at 2:01 PM, Sampsa Laine <sam...@mac.com> wrote: > > >> On 20 Apr 2016, at 20:45, Ken Cornetet <ken.corne...@kimballelectronics.com> >> wrote: >> >> Other than the OS on the old Atari 800 family of computers, I don’t know of >> any OS that supports a device to which you can supply a file name and then >> read or write data. >> >> Most OSes view disk devices as a collection of blocks. > > You’re missing my point - the guest OS would not be mounting this as a block > device, but would have some kind of file transfer utility to talk to the host > OS’s file system.
Let me flesh this out a bit, I think I understand your idea and it's a pretty straightforward one. It vaguely looks like a pseudo device implementation of the GDB remote stub file access setup. Or, I suppose, vaguely like FTP requests; they two are the same thing at a sufficiently superficial level. :-) Consider a new type of device exposed to the guest software. You can send it commands: read a file, write a file. After that command, you read from the device to get the file data, or write to it to send file data. End of file is an I/O status code (for read) or some special device operation (for write). From the application point of view this isn't all that different from guest OS file read/write calls, except that (a) it's sequential only I assume, (b) the operations are represented as device operations rather than being handled as OS calls. What you need for this to work is a way to talk to a raw device. That means directly, if the OS allows it, or if you don't have one. Or via a very simple device driver if one is required. For example, on RT11, or an IBM 1620, you could do the I/O directly. On RSTS you'd either need a driver (which is a pain) or do it through a sequence of "peek" and "poke" operations (not too bad). Yes, that seems like a notion that could be interesting. It would be good to do an existence proof, on some not too difficult machine. Perhaps a PDP11 or PDP8, with the "direct to the device" approach. paul _______________________________________________ Simh mailing list Simh@trailing-edge.com http://mailman.trailing-edge.com/mailman/listinfo/simh