Epson CP/M floppy drives. Was: C64/C128 CP/M Cartridge Interest?

Tony Duell ard at p850ug1.demon.co.uk
Mon Dec 27 13:10:08 CST 2010


> 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



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