RK04's

[Tony Duell]

> page 1-1 of the RK11-C manual  (RK11-C_manual1971.pdf)
> 
> "The high-density option provides a choice of either
>   the RK03 Diablo Disk Drive Unit or the RK05 DECpack
>   Unit, both utilizing the RK03-KA, IBM Type 2315 12
>   sector high-density disk cartridge. The low-density
>   option provides a choice of either the RK02 Diablo
>   Disk Drive Unit or the RK04 DECKpack Unit, both
>   utilizing the RK02-KA IBM Type 2315 12-sector low
>   density disk cartridge".
> 
>   low density is 12 256 byte sectors  (1100 bpi)
>   high density is 12 512 byte sectors (2200 bpi)
> 
>   both are 203 cyls, 2 tracks.
> 
>   I can't imagine there were many RK04's made..

And not all controllers supported them. The RK11-C has a bit of logic on 
it to provide a half-freqeuncy clock for the RK02/RK04 mode (it's half 
the bit densirt round the track). AFAIK the RK11-D doesn't. 

The RK11-C would appear to support RK02, RK03, RK04, RK05 using 1-of-n 
selects. The RK11-D would appear to be RK05 _only_ -- it requires a drive 
that supports binary selects (which rules out the 02/03) and it doesn't 
do low density.

I've never seen an RK04 or any manuals for it. 

-tony