flash (or ide) storage for unibus 11?
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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