16 Jan
2013
16 Jan
'13
2:59 p.m.
On Jan 16, 2013, at 4:16 AM, "Joerg M. Sigle" <joerg.sigle at jsigle.com>
wrote:
Hi Chuck,
I just reviewed the datasheets. The pinout appears *mostly* compatible -
appart from the fact that the 4116 pin 8 wants +12V, and the 4517 only
+5V. The other power supply pins have changed to N.C., so it could be
done with a small board change or a small wire by each IC.
I was just considering that because I have a machine with 64 x 4116 (and
maybe some more in two or three other boards, don't want to look
now...), and I would be interested in reducing power dissipation.
And reliability (which is probably directly correlated with power
dissipation).
Has anybody ever replaced memory ICs to save power?
Btw., I *might* have to stick with 1 bit RAM in this machine because it
might mask individual bits in hardware, IIRC.
For reliability, sure. Lots of people with 4116 boards make the
appropriate mods (or build up dozens of adaptor PCBs) to install
4164s in their place. You're only using 1/4 of the memory, but
the massively increased reliability is worth it for a lot of
people (I got two Defender board sets, and the ONLY bad ICs on
them were one burned out 74LS138 and about eight dead 4116s.
You do save a lot of power, too, but aside from heat issues
(which can, of course, be important), the power draw isn't always
as consequential for people running vintage hardware. It is a
lot nicer to old power supplies, though, and it can get rid of
a pesky -5v rail on the board that's often not used for anything
else.
- Dave