Re: Larger memory option for VAXstations

[Felix Deichmann <m4j0rd0m0%gmail.com@localhost>]

Am 19.08.2015 um 15:32 schrieb Johnny Billquist:
> I think so too. And to correct the math, the 128M means that they must
> be using 32Mx1.

OK, you wanna confuse me... :)
VS4000 with 128 MByte maxed out means eight modules with 16 MByte each, 
and each module has 36 chips (18 top side + 18 bottom side!), each chip 
with organization 4Mx1 (4 MBit x 1). A total of 288 chips...!
Look at your modules' chips: 4Mx1.

> Well, correcting my math. If we want 512MB with 36 chips means that each
> chip needs to be 128Mx1.

Hm, probably mixed MBit and MByte...
Memory organization is always specified in bits (like 4Mx1, without 
"B"), and I always wrote a "B" when I meant bytes.

Consider 512 MByte of mem. for a given VS4000/9x, we could for example 
stuff the 8 slots with 8 modules, each carrying 36 chips (total of 288 
chips as above), but we would now need 16Mx1 chips (16 MBit chips) and 
additional address lines...
This makes 4831838208 bits, which is 512 MByte with the 9 bits/byte.

> The CPU do, but does the motherboard? That was what Nemonix was
> replacing...

The MicroVAX 3100 88/98 or related VAX 4000 m108 is officially specified 
with 512 MByte indeed:

http://www.compaq.com/alphaserver/vax/download/ek-mv489-ui-a01.pdf
http://manx.classiccmp.org/collections/mds-199909/cd1/vax/vx108uia.pdf

The Nemonix upgrades for these machines seems to be more interesting 
regarding CPU speed, SCSI and ethernet, while the VAXstation 4000 
upgrade also has the memory bonus.