26 Dec
2010
26 Dec
'10
4:12 p.m.
On 12/26/2010 01:32 PM, Tony Duell wrote:
In an earlier message I did mention that my comments did not apply to
r the 3.5" drives, which are very different inside. The PF10 (I have a
non-working one [1]) uses a 6303 microcontroller IIRC, with a program
ROM, small-ish RAM, and floppy controller chip (765 IIRC). One odd-ish
feature is that the floppy dirve mechanics (stepper, etc) are controlled
by the micrtocontroller (which takes the step signal from the 765 as an
interrupt IIRC), much of the logic you'd experct to find in a floppy
drive is absent.
It's also odd in that it's a 40cylinder (67.5 tpi) device.
its first generation 3.5", also runs slower data rate.
There is a heck of a lot of elkectronics inside. One
large PCB containg a
Z80, 2K (IIRC) boot ROM ()with logic to switch it out after booting), 64K
DRAM, floppy controller, a duaghterboard with a 7201 serial chip, etc.
I have the portable battery powered single 3.5" floppy (PF10) and it's
not
so full of ram. I also have the full manuals for the system, peripherals,
both tech and programming. On occasion I hack peripherals for them.
From what others have been saying that's
easily enough to run CP/M. Note,
I am not talking about the CP/.M that runs in the
PX8 or wherever. I am
talking about the Z80 in the TF20 itself.
[1] The microcontorller has failed. Even though
it's ROMless, this is not
much of a help. Finding the right version i nthe right package after all
thses years has proved impossible. I am darn sure it's the
microcontroller in that I pulled the ROM and forced NOPs onto the data
bus, and it still had an address bus that looked crazy.
6303 is easy to find, I have a few from old defunct HDs.
On inmportatn difference to the user between the
5.25" andf 3.5" drives
is that the former need a 'system disk' to do anything useful, the latter
do not, they have the operating software in EPROM.
Looks that way.
Allison
-tony