🚀 go-pugleaf

In article <1988Nov23.104910.15213@gpu.utcs.toronto.edu>, anakin@gpu.utcs.toronto.edu (Anakin Research) writes:
> 
> 			Proposed Memory Design
>         		~~~~~~~~~~~~~~~~~~~~~~
>  
> 	I will be using 1 Meg. DRAMS in a 256K X 4 configuration. This will 
> allow expansion in 1 Meg. increments as you can afford more memory. I plan
> to have sockets for a maximum of 4 Meg. 

How about using 1Mb x 1 RAM chips, as they are much cheaper. A quick scan of
memory prices in Byte gives me :

	1Mb x 1 bit, 100ns....	$40
	256kx 4bits, 100ns....	$70


While I realise that this will mean the board must be populated with 4Mb or
no memory, the saving in memory prices seems worth it, as 4Mb of x1 RAM is
not much more expensive that 2Mb of x4 RAM.

Also, here in Australia it is just about impossible to get hold of 256Kx4's,
where as 1Mbx1's are readily available - cheaper than USA prices, interestingly.

> 	I plan to use the National DRAM controller 8428D-70. This part though
> a tad expensive $45.00 (U.S) will simplify the design and keep the chip
> count down to a minimum. It also will allow me a quicker design path. (Free

Sounds fine to me. The 8428 is a nice chip, I am told.

> 	To auto-config or not to auto-config! It seems to me that there is a 
> [comments on various options deleted]
> I would like to hear any comments on which way would be most efficent form a
> software point of view.

Me, I am happy to use AddMem. It also has the advantage that I can selectively
disable the RAM if I choose for some reason at bootup (for example for memory
tests, or for performance measurements)
Any comments?

> 	I would like to move the kickstart area into this 32-bit wide path.

I read somewhere that moving Kickstart to 32bit RAM/ROM does not have that
big an impact on speed. Perhaps Dave Haynie could comment?

>                                 Brad Fowles

By the way: Well done on the LUCAS board!

 
sns      Stuart Nixon Software
Phone :  +61 9 322 6497
Uucp  :  ...{uunet,mcvax,ukc}!munnari!acp.oz!sns 
ACSnet:  sns@acp.oz