DEC M8350 - KA8E posibus interface

[Tony Duell]

> Also... does anyone know about the differences between 4116 and 4164
> chips enough to answer the question if one could use 4164s as long as
> one a) prevents the non-TTL supplies from reaching the chips (modify

What you need to do is isolate pins 1 and 8 from the board and reconnect 
pin 8 to +5V IIRC

   4116   4164
1   -5V    N/C
8  +12V    +5V
9  +5V     A7

That leaves the extra address line tied high, so you only use 1/4 of the chip

> board, modify sockets, modify pins...) and b) possibly tie up or tie
> down the extra multiplexed address input.  Can you refresh 1/4 of a
> 4164 and have just that part stay refreshed?  I ask because I have a

There were 2 types of 64K DRAM. One of them used 7 bit refresh (same as 
the 4116, on the same pins), the other, older/rarer one need all 8 
address lines to be used for the refresh (this was a royal pain on 
Z80-based machines, where the CPU provides a 7 bit refresh only).

I have personally replaced the odd 4116 with a 4164 as I've just 
described and had no problems. Maybe I've been lucky in finding 7-bit 
refresh chips (which are the more common type), maybe it works anyway.

> serious wad of new 4164s from COMBOARD stock, but 128Kw of 4116s (8 x
> 12)  is more than I have lying around.
> 

-tony