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/.
I am pretty srue vfloppy is the one I used.
Correct. The fun thing is, the vfloppy program even
works with USB-RS232
converters :-)
That doesn;t affect me one way or the other.
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,
Interesting,
like the TF-20. I never figured out how this product has
come into being. Too much useless connectors and daugthter boards to be
designed as a single consistent design.
Yes, the TF20 seems over-complicated. 64K RAM was a lot back then (and
AFAIK all TF20s have 64K, even thoguh there are links to use 16K DRAMs).
Having to have a system disk is odd too...
And there are jumpers to have different baud rate fo the serial port, to
use a differnnt crystal for the serial port (the PSB has space for 2
oscillator circuits), and there's tat uncommitted 8255 I mentioned. The
TF20 has a lot of stuff that isn't really needed.
As I said in my other message I wonder if it was first designed as a
stand-alone CP/M computer (the hardware would be ideal for that) and then
sold as the floppy drive for the HX20 (the only modifcations being to set
the baud rate to 38400 baud and supply a diffenr system disk).
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.
I doubt it's GPIB. Althogh there was a version of GPIB using DB25
connectior (IEC625 IIRC, and the idiot who desigend the pinout needs to
be shown the clue-by-four [1]), I am pretty sure the interface on the BM5
is nothing close.
I hacve just found the unit and pulled the cocers. The nameplate on the
bakc describes as a a 'BM-5, Model number F25RA'. Inside is a half-height
floppy drive made by Hitachi, mdoel FDD541, a small PSU, and an Epson
controller board labelled 'Rabbit Board'. That board contains a Z80, 2764
EPROM, 3 oiff 6264 8K*8 SRAM, 8237 DMA controller, uPD761 disk controller
and not a lot else. Well, TTL, 26LS31, 26LS32, but no other large chips.
The host interface may be SASI/SCIS. I say this simply because there's
what may be an address selector jumper that goes from what I take to be
data lines on the intefce connecotr to a common trace. This could be the
1-of-n addressing used by SASI/SCSI.
[1] The pinout of this interface is silly. It uses a DB25 with the same
pin numbers for the same functions as the 24 pin microribbon used for
normal GPIB, and pin 25 not used. It should (IMHO, have used 1-12 and
14-25 in the obvious way. With the former pin wiring, you can't make up
adapters simply by criming a microribbon connector and a DB25 onto a bit
of 24 way ribbon cable. And if you use ribbon cable and DB25s, you end up
with signals not interleaved by grounds. As I said, the designer should
have thoguth a little more.
-tony