flashx20 - Floppy and screen for the Epson HX-20

[allison]

On 12/16/2018 10:59 PM, Fred Cisin via cctalk 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!

> The Epson Geneva PX-8 had an external 3.5" floppy available, and CP/M!
CP/M was in rom so your disk was a paltry 24k(bare PX8), 60K(multiwedge)
or 120K (Ramdisk wedge)
and of course both a 5.25 or 3.5 floppy.  The 3.5" drive could run on
internal battery.

> 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.
> I don't know about the track width; for reading, a PC can simply look
> at every other track.  And formatting a virgin disk and writing to it
> should work.  But, there is a definite possibility that RE-writing a
> PX-8 disk would result in one that the PX-8 couldn't handle (EXACTLY
> the same problem as RE-writing a 40 track 5.25" disk with an 80 track
> 5.25" drive)
>
Many of the drives have dead spots and need a manual push to start.  I
have two like that.  I suspect the
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.
>
> 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.

Allison