22 Mar
2012
22 Mar
'12
1:17 a.m.
Pertec is a pretty simple interface with handshake lines. I would
imagine you shouldn't have much trouble. An FPGA may be overkill
(certainly harder to work with 5v); you may find it even easier to
just use a microcontroller. My Cipher F880 runs on just a Z80
internally, nothing fancier than that.
My understanding of the protocol is the drive sets the speed it spits
out bytes,
and that it can be up to 1 Mbyte/sec. There is no handshaking, the read
data
is just clocked out as the feels like. I don't see how a Z80 can keep up
with that unless your formatter runs a lot slower. In theory, GCR data
coming off the drive at 75 IPS can flow in bursts up to 480,000 byte/sec.
(GCR actually records 6400 9-bit characters/inch, the 6250 refers to
the equivalent data byte density after the ECC redundancy data is removed.)
Your F880 is of course a slower drive and maybe 800/1600 only, so the
data rate can be much lower.
I have a product that uses a Xilinx FPGA connected through
the PC parallel port in EPP mode, and have used it as a development
board for several oddball projects, and so a good deal of code reuse
makes this an easier path for me. The only extra job is I have to add
a buffer SRAM to my board as the on-FPGA memory is not enough
to hold the largest tape block permitted.
Jon