[Coco] Static RAM in CoCo3?

[jdaggett at gate.net]

Roger

An HCT373A and some glue logic to use the the RAS and maybe the CAS lines to 
generate an Adress Strobe signal to aid in demultiplexing the address from the Z-
Bus. 

You have to configure the SRAM in 256Kx16 for a 512K block. That would require 4 
128Kx8 SRAMs. At least on the surface it really does not look to be all that difiicult 
a task to do.

You don't need dual porrt ram. Besides 512K bytes of dual port ram would be a very 
expensive endeavor.

As for drams they are really not analog.  Drams use a method of charge storage 
and trransfer. The refresh cycle is needed to maintain charge that is stored in a 
memory cell. A typical memory cell in a dram is a mos pn junction that forms a 
capacitor and a single switched transistor. While srams require a minimum of at 
least four transitors to form a cell. Drams offer higher denisty and speed over that of 
srams mainly due to the increased transistor count. The SRAM is more analogous 
to a latch and charge is not stored like that of a dram memory. 

A 512K or even a 2M memory of SRAM on a COco would definitely be considerably 
lower power consumption off of the power supply. At rest SRAMs draw far less 
current than DRAMS. 

james
 


On 21 Jun 2006 at 11:42, Roger Merchberger wrote:

> Working on getting my prototype ReMem running (more info here:
> http://bitchin100.com/remem_project.htm   )
> 
> I'd gotten to thinking:
> 
> How much heartburn & voodoo would it take to get some static Ram shoehorned 
> into a CoCo3?
> 
> {Dreaming...}
> 
> Is it as simple as getting really fast RAM (would dual-ported be 
> necessary?) and ignoring the refresh cycles....
> 
> {/Dreaming...}
> 
> This is a question from a guy who understands CPUs, busses, TTL, and other 
> shiznit, but have never really gotten my head around much analog circuitry 
> & the black magic of dynamic RAM (which, AFAICT technically, is an analog 
> critter after all... ;-)
> 
> Now that big (to a CoCo) but small (physically) and low power (again, to a 
> CoCo) Static RAM is available on the cheap, I'm guessing it's more voodoo 
> than science stopping it's use, else someone would've figured out how to 
> make it work...
> 
> Just random, yet foolish thoughts on my 13-hour-wednesday...
> Laterz,
> Roger "Merch" Merchberger
> 
> --
> Roger "Merch" Merchberger   | "Profile, don't speculate."
> SysAdmin, Iceberg Computers |     Daniel J. Bernstein
> zmerch at 30below.com          |
> 
> 
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