Re: MMU prototyping

From: Jim Brain <brain_at_jbrain.com>
Date: Thu, 24 May 2018 12:38:49 -0500
Message-ID: <8cacb5e0-0f38-2bd8-1913-fe8e5038462d@jbrain.com>
On 5/24/2018 9:24 AM, smf wrote:
> On 23/05/2018 17:46, Jim Brain wrote:
>>  * PHI2 is HIGH AND
>>  * Address[15:12] != 0 AND
>>  * Address[15:12] != D AND
>>  * the current PAGE!= 0
>>
>> PAGE is an 8 bit (soon to be 16 bit) value denoting which 4kB page is 
>> mapped into the selected page of main system RAM.
>
> What would happen if you always asserted GAME? Other than losing 
> access to most of the onboard ram.
>
>
>
You would get exactly that.  All RAM except the 4kB at the bottom and 
the IO page would disappear.  If you were able to configure this unit to 
replace the open space with RAM, the entire rest of the memory map would 
have RAM in place for all CPU cycles.

Jim

-- 
Jim Brain
brain@jbrain.com
www.jbrain.com
Received on 2018-05-24 20:00:09

Archive generated by hypermail 2.2.0.