Disk hardware emulation, was Re: Grandfather system RTE6/VM?

From: Tom Jennings <tomj_at_wps.com>
Date: Mon Dec 8 20:10:58 2003

On Sun, 2003-12-07 at 10:47, Tony Duell wrote:

> So you have to buffer an entire cylinder's-worth of data in the emulator,
> and keep on squirting out that part that corresponds to the selected
> 'head'. When the classic steps to a new cylinder, you have to save one or
> more of the 'tracks' in the emulator's RAM buffer (you can flag writes to
> particular tracks, since there is a write gate line, but you also have to
> assume that it's possible the classic has written to all 16 tracks in the
> cylinder -- it certainly would when formatting). Then you have to reload
> all 16 tracks-worth of data from the modern hard disk, and then assert
> seek-complete to tell the classic that the drive (emulator) is outputting
> the data for the new cylinder.

I had forgotten this about ST506!

But hell, RAM costs being what they are, the whole disk image could be
kept in memory, with a dirty bit and/or timer to write changes to
permanent store to avoid data loss, in the simulator.

Hmm... how about a hardware simulator, with a USB port on the back side
that connects to a host computer. You load the "ST506" image into the
simulator, copy it back out for safe keeping when you're done.
Received on Mon Dec 08 2003 - 20:10:58 GMT