"intelligent" disk drives

[Curt at Atari Museum]

The Atari 8bit computer disk drives, were were SIO Bus (Serial I/O Bus - 
what amounts to a very early version of USB) were the 810 and Atari 1050 
disk drives which used 6507's for communicating to/from the host Atari 
PC as well as a WD floppy controller (Atari 810 - 1771, Atari 1050 - 
2793 or 2797 depending on revision of model)

The later XF551 Atari 8bit disk drives used an 8040/8050 and WD 1772

Everything on the Atari SIO bus were essentially "Intelligent 
Peripherals" that had to have their own CPU chip in order to talk across 
on the SIO Bus.    It was a nice design and its over-sized trapezoid 
connectors made hooking up (Daisy Chaining) peripherals an easy 
no-brainer/no mistake setup.      However, these intelligent peripherals 
ended up hurting the Atari 8bit line because of their inherently high 
expense.     It was interesting - in 1983 you could buy an Atari 800XL 
computer for around $299, but the 1050 XL series disk drives cost $359 
or higher, so the cost of owning a disk drive was a luxury, owning two 
such devices was a rare sight to see for many Atari users at the time.

The 1772 were also used on most of the 16/32bit Atari ST computers.

Atari would later develop a custom IC called "Ajax" for high density 
floppy drive usage. (Atari IC part#'s C302096, C302434)



Curt




The Atari XF551

Geoff Reed wrote:
> 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.)
>
>