flashx20 - Floppy and screen for the Epson HX-20

[wrcooke at wrcooke.net]

> 





On December 16, 2018 at 11:14 PM allison via cctalk <cctalk at classiccmp.org> wrote:
> 
> > On Sun, 16 Dec 2018, Norbert Kehrer via cctalk wrote:
> >> I have not tested it, but I suppose, that also the PX-8 and PX-4 used
> >> the protocol,
> >> because the protocol specification defines the following device numbers:
> >> - HX-20: 0x20 (probably also used for the HC-20)
> >> - PX-8:  0x22
> >> - PX-4:  0x23
> >
> >
> >
> PX-8!
>
A subject dear to me.  I still have the px-8 I bought new (borrowed the money from my sister) as a young man in 1984.  Alas, I could never afford the PF-10 disk drive.
 

> > However, the PX-8 3.5" had 40 cylinders, with 67.5 tpi, instead of the
> > common 80 cylinder 135 tpi of other 3.5" disks.
> > Those 40 cylinder 3.5" drives are quite rare.
Somewhere in my searches I recall reading that the 3 1/2" drives used the same format as the 5 1/4" ones.  Maybe 40 tracks of 16 256 byte sectors.  Oddly, I believe that 2 tracks are "reserved for CP/M" even though it is in ROM and not stored on disk. 


> ceramic magnet lost its stuff over time.  When I have time the next
> project will be a Atmega2650 running
> a CF to via serial interface.  The drive table can be patched for a
> larger (up to 8mb) drive.
I've been planning something very similar for a while, but using an Arduino (ATMega 328) or bare AVR chip and probably a smaller/simpler flash chip.  I din't know about the drive table.  That's interesting.  Would a new ROM have to be burned with the new table?  Do you have an links to the info?

> >
> > With appropriate format handling software on the PC, it should be
> > possible for a PC connected using your system to work with actual
> > Epson diskettes, and emulate the Epson external drives.
> >
> There are several software packages on the net to do the fake of the
> disk via serial and manuals of the system to
> explain the format.  Likely that software could do the earlier HX20 (and
> friends) with minor tweaks.

Here is one I am familiar with that runs on Linux.  Only does drives, AFAIK, no display.
https://fjkraan.home.xs4all.nl/comp/px4/vfloppy/

And if anyone is interested here are some more links:
http://oldcomputer.info/8bit/hx20/index.htm#links
Navigating through some of those links takes you to the protocol:
https://fjkraan.home.xs4all.nl/comp/hx20/epsp.html
Note at the bottom of the page it says the PX-8 and CP/M only use four of the functions.
This link has lots of HX-20 info.  
http://electrickery.xs4all.nl/comp/hx20/doc/index.html
The tms files near the bottom (ch 10-11?) describe the protocol and how it functions in detail.

Will

"He may look dumb but that's just a disguise."  -- Charlie Daniels


"The names of global variables should start with    // "  -- https://isocpp.org