Modifying a RXV21 for an 11/83

[Chris Zach]

> Most of the third party controllers and drives are OS compatible with 
> the RX01 + RX02 format, provided you stick with Single Sided media.  
> However, booting an OS with an RX01 controller handler (Interrupt 
> driven) will not succeed with an RX02 controller (DMA) or vice-versa.

Ok, not a biggie, I can just VMR a new RX01 compatible disk with a DY: 
boot driver in RSX11M+. Really there are two reasons for the RX drive: 
Boot BRUSYS so I can backup/restore the system to TK50 tapes, and build 
disks for the PDT11/150.

Well there is a third reason: I have here a box full of floppies that 
include a full install set of TSX11+. This is 5.1c with a full license. 
These are "double sided" in that there are two sector holes in each disk 
so you can flip them over and have the sector pulse light work.

There is also SaturnBase, SaturnCalc, and SaturnGraph, 3.0 with a 3.0k 
upgrade/patch disk.

Not sure if these exist elsewhere but I could make copies now with the 
pdp11gui and finally slurp them into images. Do these already exist in 
archives? Before putting these in I'd make sure to clean the heads and 
everything so they don't take any damage.

> The Double Sided media (RX03) make for interesting interchange stories. 
> I've seen double sided single density floppies. There are also 
> differences in how the controller vendors made disk handler 
> modifications for RT11.   Many of these controllers would allow you to 
> perform a low level format, but only using vendor specific controller 
> commands.   The DEC RX02 will only change the funky media density.

Yah. I think Solarex used the MXV21 controller from MTI and it seems to 
have its own unique format and an "FD:" driver. Which means I would be 
stuck with RT11 4.0 which kinda sucks so why not

> 
> Remember that these are 18 bit controllers.   Some operation systems can 
> work around this limitation, at the expense of CPU cycles.

Indeed. It's pointless to use them with RSX11 unless as I said to do a 
boot disk for tape backup/recovery. But I started out on RX01's way back 
when so I do have a bit of a soft spot in my head for them....

CZ