[Info-vax] RB730 Integrated Disk Controller (R80/RL02) usable with VAX-11/750?

[Johnny Billquist]

On 2011-05-02 17:05, SeanOBanion wrote:
> On May 2, 2:52 am, vaxorcist<vaxorc... at googlemail.com>  wrote:
>> Can the RB730 Integrated Disk Controller (primarily developed for R80/
>> RL02 drives with the VAX-11/730 and /725) be used with the VAX-11/750?
>> This might have been a "low cost" solution to connect disk drives to
>> the /750.
>>
>> Any hints welcome!
>>
>> Regards,
>>
>> Ulli
>
> No.
>
> The IDC is part of the 730 CPU, stealling CPU cycles in a hidden way
> to get it's work done.

Cute. I have never examined the IDC in detail... :-)

> The later version of the 730 did away with the IDC for a single UDA50
> Unibus adapter that also reduced the amount of memory the system could
> support:
> system memeory of a 730 sat on the Unibus.

What??? Are you sure? The Unibus only have 18 address lines, which means 
256K addressable. And some of that is needed for I/O. I would be very 
surprised if memory really sat on the Unibus.

	Johnny

-- 
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