Static RAM chip source (& S-100 related questions...)

[allison]

On 08/15/2010 03:02 PM, Chuck Guzis wrote:
> On 15 Aug 2010 at 10:12, Glen Slick wrote:
>
>    
>> One other thing that might help the situation is that the 2147 enters
>> an automatic power-down mode when the CE# input is at a high level.
>> For example the datasheet for the CY2147-35 says the max operating
>> current is 125ma while the max standby current is 25ma.
>>
>> Do MM5257 parts enter a standby mode when not selected?  I don't have
>> a datasheet handy.  Which would draw more current total, two banks of
>> MM5257 parts, or two banks of CY2147 parts where at least one of the
>> two banks should be in standby mode?
>>      
> If the 5257 parts are like the TMS4044 parts, standy is entered by
> reducing Vcc to 2.4V.  Otherwise, maximum operating power dissipation
> is given as 303 mW.  I somehow doubt that the memory board in
> question has the smarts to drop Vcc.
>
> There also exist CMOS versions of the same chip--the Motorola
> MCM146504, the Harris HM6504 or the Intersil IM6504 is one such, with
> a standby power of 10mW.  These are the same speed (450nsec) as the
> TMS4044s.  So more grist for your mill...
>
> --Chuck
>
>
>    
Watch out,
Some parts like the 6504 are not fully static and the
logic is somewhat dynamic with the transition of CS
performing the precharge of the gating logic around a
static cell.  That means you must cycle CS for every
address change withing a read/write or RMW cycle.


Allison