flash (or ide) storage for unibus 11?

Johnny Billquist bqt at update.uu.se
Tue Nov 24 04:13:01 CST 2015

On 2015-11-24 10:01, Rob Doyle wrote:
> On 11/24/2015 12:46 AM, Johnny Billquist wrote:
>> On 2015-11-23 20:30, David Bridgham wrote:
>>>> For a classic/straightforward programming interface, the Massbus
>>>> disks (RP04 and successors) are a good choice.  That will take
>>>> you just over 500 MB, if you emulate the layout of the RP07.
>>> Current thinking (at least my current thinking) is RK11 first then
>>> probably RP11, both optionally extended to support Q22 addresses.
>>> Also something we're calling the RQ11 which will be our "native"
>>> interface with variable sized disks with a 32-bit linear block
>>> address giving 2TB disks for those who are willing and able to
>>> write their own device drivers.  Finally, most likely the RH11 for
>>> some Massbus disks with 22-bit addressing.  After that, I'm
>>> thinking to call it good and move on to other projects though I'm
>>> certainly willing to talk to anyone who has a particular disk
>>> controller they want to implement.
>> 22-bit addressing is not possible on the Unibus. The RH70, which is
>> the massbus controller for the 11/70 do 22-bit addressing, but it
>> manages that by not sitting on the Unibus.
> The RH11 has 'paging' on the controller. It can translate between Unibus
> addresses and memory addresses.

I don't understand what you mean by that.
The RH11 do DMA, just like all other disk controllers I know of.

The Unibus only have 18 address bits. Thus, it is impossible to do 
22-bit addressing for any controller on the Unibus. No matter what the 
controller do internally.

Unibus machines with a 22-bit memory address use soemthing called a 
Unibus map to translate the 18-bit Unibus address into a 22-bit memory 
address when you perform DMA.
The Unibus map is a part of the computer, and the controller on the 
Unibus do not even know it exists.


Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol

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