Which PDP?

[Tony Duell]

> Disks are probably going to be your biggest problem... the RK05 was a
> common disk in the 11/34 era, at 2.5MB per drive (4 drives per
> controller).  v7 might fit, but 2.9BSD will be _really_ cramped. 

Actaully 8 drives per controller, but even so it's crampped. And 8 RK05 
drives take up a heck of a lot of space!

> RL02s may be easier to locate, but they are 1980s tech essentially,
> and even at 10MB, are a bit on the small side for UNIXy work (but are
> great for RT-11, etc.)

What abnot the RK06/RK07 (14MB and 28MB per drive repsectively, I think, 
up to 8 drives per controller). Probably actually 1980's units, but still 
top-loading demountable drives, 2 platters in the pack (3 data surfaces, 
1 servo surface). Electronics is loads of simple chips (TTL, op-amps, 
etc). If you understand the servo in one of those, you've got somewhere ;-)

> If an 11/23 is not too new (it might be 1979), it's a nice choice
> because a) it's 22-bit (except for rev A boards)allowing up to 4Mb of
> RAM, b) it _is_ compact, c) it's expensive, but a Qbus SCSI card is
> easier to find than a Unibus SCSI card.  They are also somewhat common
> (I got my first one in 1986 for a whopping $300, then used that to do
> work on a contact that was my bread and butter for two years)

Be aware that the 11/34 (And the 11/35, 11/40, 11/45 that others have 
recomended) are traditional 1970's designs, all TTL and small PROMs. The 
11/23 is an LSI design with the CPU in a few DEC custom ICs. This is a 
real minus point against the 11/23 for me.

-tony