22 Jun
2005
22 Jun
'05
5:50 a.m.
At 11:58 PM 6/21/05 +0100, you wrote:
Tony,
This is good info. Someone should post it as a mini-FAQ.
Do you have any info on which ones used 7 bit refresh and which ones used
8 bit refresh?
Joe
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