If you want to copy files from drive to drive then a
decent sized buffer
helps speed things. FYI a copy of CP/M bdos and a bios for drives
has a ram/rom cost of not less than 3.5K (bdos) and likely about 1.5K
(bios) and the file transfer application (CCP is 2K) so thats 8K in itself.
A reasonable buffer is 16K so your to 24K plus rams (that era) were
1/2/4/16/64K Where 32K was generally oddball half good parts.
So with a z80 the cost to do 16 or 64K is able the same in logic and the
difference is cost of eight 16K parts becommin passe` vs eight 64K
parts getting cheaper. To me sounds like rom and ram were available
enough to allow software design to take a cheaper (less time) route.
The TF20 controller vboard takes 8 DRAM ICs, and there are links to use
either 4116s or 4164s. AFAIK all production versions had 64K of RAM
I;'ve been reading some manuals on the web. The translation is a little
'quaint' in palces but it appears Epson planned (or made) a product in
the same cause, using the samedrives, but no cotnroller. Basically a dual
5.25" floppy drive with a SA400-like interface. Makes a lot of sense.
I also wodner if they planned to make a CP/M computer in the same
cabinet. It would have neen tirivial to do. The TF20 controller board ans
weiral board would have done. Just slow down the serial port to, say,
9600 buad (and there are links for that on the serial daughterboard) and
change the boot disk to have a normal CP/M CCP on it. It would actually
be a fairly nice CP/M machine, there's a second serial port (other half
of the 7201) and a parallel interface (the not-fitted 8255 I mentioned).
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.
It does but it does not so file level services it's strictly at the
Sector level.
I thought I'd used with the HX20, but maybe not...
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.
Different from the PF10. Epson did some interesting things overall.
Oh, the TF20 and PF10 are _totally_ different.
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.
Motor control or maybe a parallel bus for the PX8 or NEC8201
It's not motor control. There are ports for tht anyway. The 8255 is not
normally fitted from whar i can tell, and all 24 port lines got to a 34
pin header, aong with grounds and IIRC a reset input. May be a parallel
host interface, may be for some periperhals that were enversupported.
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.
Never seen that.
I don;t think anyone has :-). I am sure it has nothing to do with the
portable machiens (the host interface is certianly parallel), but I can
find no mention of it anywhere. Doubtless one day somebody will recognise
it...
-tony