27 Dec
2010
27 Dec
'10
1:53 p.m.
The HX-20
commands are file based and were issued mainly from Basic. The
Basic
extension is also on the boot disk.
The PX-4/8 commands are sector based and issued from CP/M.
Although IIRC the disk
BASIC for the HS20 had DSKI$ and DSKO$ commands
(or something similar) to read/write absolute sectors. There's also a free program for linux machines to
emulate such a drive.
Amazingly it works on my acient linux box, and from what I can remember,
it works with the HX20 and PX4/8 machines.
There are several programs. The Px8vfs
program for DOS (and OS/2) is
written by Will Rose and I got it via Don Maslin a long time ago:
http://www.xs4all.nl/~fjkraan/comp/px8/px8vfs/index.html. The other is
Vfloppy,
originally written by Justin Mitchell and maintained by me:
http://www.xs4all.nl/~fjkraan/comp/px4/vfloppy/.
The images of the latest version are also usable with the PX-4/8 and
QX-10 emulators.
IIRC, at the hardware level it's RS232 voltages,
38400 baud. Probably 8
bits, no parity, 1 stop.
Correct. The fun thing is, the vfloppy program even works
with USB-RS232
converters :-)
The TF-15 and
PF-10 are both ROM based. The TF-15 used the same housing
as the TF-20. As this resembled the QX-10 computer, the origin of the
TF-15/20 product was probably to provide two extra floppies for this
computer.
Of coruse the floppy drives in the TF20 (and maybe the TF15, I've
never
seen one) are the same voice-coil drives as in a QX10.
There's a 34 pin header on the nback of the TF20, which would appear to
be for adding a couple of exter external drives. AFAIN, the software
doesn't support it, though.
More interestingly, there's a parallel interface inside the TF20 (8255 +
header), I can't remember if it's populated, or if the PCB is simply laid
out for it. I have no idea what this was supposed to be used with.
The serial inbterface in the TF20 is a daughterboard. Whether other
interfaces were planned to fit in place of it I don't know.
I also have another Epson prodcut in a very similar case. it's called
something liek a 'BM5'. The external interface is a DB25 socket, but it's
not RS232, it's some custom patallel interface. Inside is a PSU, controller board and 5.25" floppy drive. But
it's not a standard drive at
all. The interface between the cotnroller and drive is a 34 way and a20
way ribbon cable, the controller board has a _hard disk_ controller IC on
it (one of the NEC ones). I believe the drive interface to be close to
ST412, and the drive to take special floppies (possibly with servo
tracks) and to have a rahter high capacity. I bought this thing 15 or so
years ago (back when Greenweld sold interesting stuff) and have never
been able to fidn out anythign about it. Oh well... It was probably a
peripherals for the QX10 or something, but I have never seen an interface
card for it.
Could it be a GPIB interface? There is such a card for the QX-10
(http://www.xs4all.nl/~fjkraan/comp/hx20/epson_codes.txt) and I know HP
used this interface for hard disks in the HP9000 / 300 machines.
-tony
Fred Jan