17 Nov
2007
17 Nov
'07
12:26 a.m.
the C= disk drives were pretty much all smart drives weren't they? the big dual
drive units had a controller card in them that was basically a small computer (IIRC)
also Atari disk drives had a 650x IIRC in them as well as a disk controller chip
(once again IIRC.)
The Epson TF20 is a double 5.25" drive used with their early laptops
(HX20, PX4, PX8, etc), it communicates with then over an RS232-level
serial link at 38400 buad.
The TF20's controller board is packed with chips. As well as the disk
controller chip, there's a Z80A, 64K of DRAM (more than the host computer
in some cases!), a boot ROM that is paged out after the drive unit has
booted, and lots of glue logic. A daugterhboard contains a 7201 chip and
the RS232 drivers/receivers.
I am told it boots a modified CP/M from the disk in the A: drive at
power-on.
The drives themselves are somewhat interewting, being the Epson 1/3rd
height units with a voice-coil head positioner.
-tony