Would a bog-standard 4164 be a suitable replacement for a MCM4517 in a Sega SC3000H? (was Re: Introduction - Terry Stewart (tezza))
20 Oct
2010
20 Oct
'10
2:15 p.m.
On 10/19/10, Mike van Bokhoven <mike at fenz.net> wrote:
Hi Terry,
Welcome to the list, from another NZ classic-cmper. Whereabouts in NZ are
you located?
Hi, Terry,
I'm curious, too. I've spent about six months of the past 15 years in
NZ, mostly in Christchurch, with trips to Wellington, Auckland, and
Hamilton.
I also enjoy getting dead machines going; my current
challenge is finding
RAM for a Sega SC3000H. I was hoping someone might have some spare MCM4517s
for sale (from memory, hopefully that number's right),
Those are just +5V-only 16Kx1 DRAMs, right? The pinout is the same as
the 4164 except for pin 9 (NC on a MCM4517, A7 on a 4164).
Could you use a 4164 instead? (it might require a pull-up or
pull-down on pin 9 so it doesn't float). Those are rather abundant
and still available from a number of sources.
-ethan
20 Oct
20 Oct
2:26 p.m.
New subject: Would a bog-standard 4164 be a suitable replacement for a MCM4517 in a Sega SC3000H? (was Re: Introduction - Terry Stewart (tezza))
On Wed, 20 Oct 2010 17:15:29 -0400, Ethan Dicks <ethan.dicks at gmail.com>
wrote:
Interesting thought... I probably have some 4164s around somewhere as well.
Having said that, last night I bought a couple of MCM4517s from a Chinese
seller on eBay. Their feedback seems pretty good, but I am wondering if
I'll receive dead parts, or maybe even compeltely different parts with fake
labelling. I'll be optimistic for the moment I guess! If it doesn't work, I
might see if I can find a known-good 4164 around my place, and give it a
try. Thanks for the heads-up on that one.
Mike
> I also enjoy getting dead machines going; my
current challenge is
finding
RAM for a Sega
SC3000H. I was hoping someone might have some spare
MCM4517s for sale (from memory, hopefully that number's right),
Those are just
+5V-only 16Kx1 DRAMs, right? The pinout is the same as
the 4164 except for pin 9 (NC on a MCM4517, A7 on a 4164).
Could you use a 4164 instead? (it might require a pull-up or
pull-down on pin 9 so it doesn't float). Those are rather abundant
and still available from a number of sources. 
5:48 p.m.
New subject: Would a bog-standard 4164 be a suitable replacement for a MCM4517 in a Sega SC3000H? (was Re: Introduction - Terry Stewart (tezza))
On 10/20/2010 02:15 PM, Ethan Dicks wrote:
Could you use a 4164 instead? (it might require a
pull-up or
pull-down on pin 9 so it doesn't float).
I'd just hardwire pin 9 to either
+5V or ground. Probably easiest to
tie it to +5V on pin 8.
16K DRAMs all required 128 row refresh in 2 ms.
64K DRAMs came in two kinds. Some required 256 row refresh in 4 ms,
while others (specifically intended for compatibility with 16K DRAMs)
required only 128 row refresh in 2 ms. The latter kind will work with a
7-bit refresh counter (e.g., 3242, or the counter built into the Z-80),
while the former will not.
However, in this case, you're only going to use 128 rows (and only half
of each row), so either kind of 64K DRAM should be suitable.
Eric
21 Oct
21 Oct
1:02 p.m.
New subject: Would a bog-standard 4164 be a suitable replacement for a MCM4517
On 10/20/2010 02:15 PM, Ethan Dicks wrote:
I've replaced 4116s (3-rail) with 4164s in an 'emergency'. Bend out pins
1 and 8 (-5V and +12V on the 4116, N/C nad +5V on the 4164) and jumpr pin
8 to pin 9 (+5V on the 4116, A7 on the 4164) on the chip. Then plug it
in. This, of couse ties A7 high since it's going into the 5V pin of the
socket.
Could you use a 4164 instead? (it might require
a pull-up or
pull-down on pin 9 so it doesn't float).
I'd just hardwire pin 9 to either
+5V or ground. Probably easiest to
tie it to +5V on pin 8.
16K DRAMs all required 128 row refresh in 2 ms.
64K DRAMs came in two kinds. Some required 256 row refresh in 4 ms,
while others (specifically intended for compatibility with 16K DRAMs)
required only 128 row refresh in 2 ms. The latter kind will work with a
7-bit refresh counter (e.g., 3242, or the counter built into the Z-80),
while the former will not.
However, in this case, you're only going to use 128 rows (and only half
of each row), so either kind of 64K DRAM should be suitable.
I asusme in all cases, the row that's seleected by a particular address
is also the row that's refreshed by that address, so the rows that get no
refesh are the ones that are never used in this arrangement. I can think
of no sane reason to desing a DRAM any other way, but...
-tony
27 Jan
27 Jan
7:26 p.m.
New subject: IBM Centennial Film
Its a big long commercial but, some may get a kick out of it here. They
quickly skip over WW2 of course.
http://www.youtube.com/watch?v=39jtNUGgmd4
28 Jan
28 Jan
2:46 p.m.
New subject: IBM Centennial Film
On 1/27/2011 9:26 PM, leaknoil wrote:
Its a big long commercial but, some may get a kick out
of it here. They
quickly skip over WW2 of course.
http://www.youtube.com/watch?v=39jtNUGgmd4
I just found it curious that the artwork at the 1401 introduction
contains a good bit of punched paper tape.
Later,
Charlie C.
4845
days inactive
4945
days old
5 comments
6 participants
participants (6)
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ard＠p850ug1.demon.co.uk -
csquared3＠tx.rr.com -
eric＠brouhaha.com -
ethan.dicks＠gmail.com -
leaknoil＠gmail.com -
mike＠fenz.net