>No systems that shipped used EDO. We went from FPM to SDRAM.
Not entirely accurate... although the ones I was thinking of don't use
EDO anyway (my memory told me the 660AV and 840AV required EDO memory
installed in pairs... I just looked it up and it appears I'm wrong, they
However, there ARE Macs that require EDO (according to Apple), but upon
looking that up, it looks like it may only be DIMM based machines, so it
still wouldn't apply to this instance (where I said there were some that
required EDO 72 pin SIMMs).
So you are correct, it appears that there are no 72 pin simm based units
that require EDO, however, EDO is required in some Macs that use DIMMs
(which as everyone knows is NOT the same thing as SDRAM). Specifically,
the 4400, 5500, and 6500 require EDO... and the 7200 can NOT use EDO, in
fact there is a note saying it may damage the machine. The rest can use
FMP or EDO simms or dimms (according to the same chart, the 8100, the
system in question, wants FMP but will use EDO as FMP if EDO are
installed... which is consistant with what I have found of any other 72
pin SIMM mac I've upgraded)
>Ordinary PC-type 72-pin SIMMs should be fine, but I think you need Fast
>Page Mode rather than EDO.
Based on my findings, I've yet to run into a Mac that can't use EDO. Some
require EDO, but so far, all the ones I've played with that are supposed
to use FPM, work just fine with EDO instead. (note: I have never upgraded
an 8100, so for all I know, that could be the one model that really does
Again, this is based on 72 pin SIMMs. It seems that Apple's 72 pin SIMM
requirements were pretty loose compared to their other memory
>I have a Powermac 8100/80 that needs a RAM upgrade. Lowendmac.com
>says that it can handle 72-pin SIMMs, up to 32MB each. My question is
>this: does it take the same 72-pin SIMMs as a PC, or does it require
>special "mac-only" SIMMs? Google only showed people still selling the
>RAM (for outrageous prices), and I couldn't get actual specs on the
Plain old cheap PC simms work fine. If you can, get non-parity as that
was what it really called for, but I have successfully used parity in any
mac I've tried (that require 72 pin simms that is... 30 pin ones will NOT
work with parity for the most part... there are a few exceptions like the
version of the IIci that was specifically designed TO use parity, as well
as IIRC, some of the last models to use 30 pin would work with either
You should be able to pick them up cheap from enough places. One thing in
your favor... the Mac isn't very picky about matched simms, so you may be
able to buy a bunch from somewhere like 18004memory.com that sells
unmatched parts pretty cheap in their clearance section.
I have a quad Qbus board in front of me. It is labeld "System Industries
9901-6082-A". It has two 40 pin IDC connectors, lots of TTL, four
AMD2905, three EPROMs, the usual PALs, ...
This is some sort of disk controler according to google. What I didn't
find out: Is this the complete controler or is this only a part of a
controler? There is a "System Industries 9900". It is a separate 19"
rack box containing a SMD (?) controler. It is interfaced to SBI or
UniBus or ??? with a bus interface card and ribbon cables. Maybe the
card I have is the QBus interface card?
I am a happy owner of a IBM System/3. This system was standing unpacked
in my garage for more then 10 years waiting to be put back into service.
If was stored in perfect working condition.
Last week I started to restore my old IBM system/3 to working condition.
After solving several problems in the power up sequence the system was ready
to be IPL-ed.
Immediately I had a processor check. Checks lights indicated storage problems.
After investigation I discovered that the several X wires on the core planes where open.
These wires are mounted by IBM on a square frame. During a heavy forst period
(I live in the Netherlands) while standing in a unheated garage the copper
X wires shrink and broke. About 20% of the X wires are broken.
None of the Y wires (???).
These planes are stacked on top of eachother by IBM and the X/Y wire terminals are
welded together. This makes the planes non-accessible to repair the open wires.
I now have 2 unit (each 32k) both located in the system defective beyond repair
and idem a spare unit of 16k.
Any one who has such IBM storage unit available to bring my IBM S/3 back to live...?
On Wed, 29 Dec 2004 "Pierre Gebhardt" <cheri-post(a)web.de> wrote:
>>> That's the info I found on the net from a 11/750 FAQ:
>>> "National Semiconductor Memory Systems: 1Mb memory boards. These
>>> boards have PWB 551109464-002 B
>>> PWA 980109464-001 D
>>> etched on them. They have a push-button switch for disabling the
>>> board, and a spare memory chip in a socket on the board. Board has
>>> green and yellow LEDS, which should normally both be on. Disabling
>>> the board causes the yellow LED to go out, and the red LED on the
>>> L0016 to come on, indicating bad memory configuration."
>> Those almost certainly aren't UNIBUS memory boards, but are
>> 11/750-specific boards.
> Thanks for this information, Patrick.
> I guess, I'll have to wait for such a VAX, I haven't one yet ;-)
Actually, the memory system in a VAX-11/750 are specific to that model.
It's not compatible with the VAX-11/780, nor the 11/730.
However, the memory backplane is compatible with the MK11 memory box for
the PDP-11/70. Unfortunately, the MK11 controller only deals with 256Kb
memory boards. So if you'd like to use these 1 Mb memory boards in an
11/70, you need a small hardware hack, and a small software hack.
The hardware hack is to tie four board select lines from the backplane
into to address lines for the memory card, and the software hack is to
reset all the ECC bits in the high 768K of each card, since the MK11
controller only clears ECC on the low 256K.
I have done both of these things on an 11/70 here in the past.
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt(a)update.uu.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
At 23:21 29/12/2004 +0000, you wrote:
>> Hi Guys,
>> Just picked up an Tektronix Model 31 desktop calculator. This is a
>> fairly old (early 70s) desktop programmable with built in tape storage
>> and printer.
>> Looking for information/documenation on it - all I got was the bare
>> unit (which looks to be in good shape).
>It's not much, but somewhere I have the service manual for the 4661
>plotter that was used with this machine. I think at least I could get you
>a pinout of the I/O connector if that's of any interest.
If you already have it scanned, I would love a copy, however don't go to the
effort of copying it just yet if you have not already done so. I am unlikely
to actually use the I/O port in the near future...
Btw, checked it over this afternoon and applied power - came right up and
everything seems to work - even figured out how to write (and run) a short
program on it!
dave04a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Collector of vintage computing equipment:
I have a wyse wy-50 and a vt101 in good condition that I need to get
rid of... I'm wondering if they're even worth putting on ebay.
yes, esp if the vt101 has a working power supply.
I don't know what is is about late 70's DEC switchers, but
just about everything I have now with them in is dead (VT100's,
11/44's, et al)