On Jul 30, 21:54, Richard A. Cini, Jr. wrote:
> Subject: ZX-81 custom chip - watizit?
> I just got a ZX-81 kit (unassembled). I didn't know this before, but the
ZX
> uses a custom 40-pin IC to perform certain I/O functions. Is this chip
truly
> "custom" or is it a relabeled Z80 support chip?
No, it's a ULA (uncomitted logic array, a sort of early ASIC) made by
Ferranti. The ULA replaces several TTL chips that were present in the
ZX80. There were two or three revisions of these, and a similar idea was
used in the Sinclair Spectrum. The BBC Micro also used Ferranti ULAs, one
for the serial controller and one for the video controller. IIRC, the ZX
and Spectrum ULAs are still available from CPC in Britain.
A ULA consists of lots of simple logic gates laid out in a square array,
but the basic design has no final metalisation layer - and hence no
interconnections between the gates. A designer using a ULA would translate
his circuit diagram into an interconnection diagram for the array, and hand
that over to Ferranti, who would then produce the mask for the final stage
of the manufacturing process. The end result is a bit like an FPGA, but
with simopler building blocks. Apart from that, the relationhip between a
ULA and an FPGA is bit like the relationship between a masked ROM and an
EPROM.
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
O.K. I've NEVER seen a 1400 with an 8088, though. does anyone have one?
--
-Jason
(roblwill(a)usaor.net)
ICQ#-1730318
----------
> Part substitutions like this are very common, especially with very
similar
> parts like the 8088 and V20. Sometimes manufacturers run into problems
> getting the chips they need, and often have to take far more drastic
> measures, like coming up with kludge boards, piggybacking parts, hacking
> up the traces, etc., just because vendor A is saying "12 weeks" and
> customer is saying "next week", all for a $4.00 part.
>
> William Donzelli
> william(a)ans.net
>
At 05:38 PM 7/30/98 -0500, you wrote:
>On Thu, 30 Jul 1998, Richard A. Cini, Jr. wrote:
>
>> Does Wierd Stuff Warehouse in Sunnyvale have a web site? How about a phone#
>> (the one that I have "...has been disconnecte.")?
>
>Yes, but you have to know how to spell weird :-)
> http://www.weirdstuff.com
>
>Tell 'em one of the local weird collectors sent you.
DANG! Wish this had come up about a week ago. I was in California and
wanted to see "Weird Stuff", but when all I could track down was the
'disconnected' phone number, I gave up... (no real access to mail/web
while I was traveling)
DRAT and such...
-jim
---
jimw(a)agora.rdrop.com
The Computer Garage - http://www.rdrop.com/~jimw
Computer Garage Fax - (503) 646-0174
I was at a computer junk store the other day and saw a long flat
computer case/box; about 3 inches high, about 18 wide and 10 long. It
was some sort of unix terminal/system/something, because it still had a
label with the network host name etc on it.
BUT-
it said m88k on it! it might have also said NCR but I'm not sure. what
kind of things are used on the 880x0's? I know NetBSD has an m88k port
but who or what would have originally run on such things, and how old
are they? I have to admit it piqued my curiosity. If possible I'm going
back to grab the thing. One last question- how do the 88k's compare to
the 68k's or a MIPS chip? I remember some discussion about SGI switching
to MIPS instead of using the 88k due to slow development or something to
that effect. (whether that's true or not I have no idea, so don't flame
me :)
-Eric
I just got a ZX-81 kit (unassembled). I didn't know this before, but the ZX
uses a custom 40-pin IC to perform certain I/O functions. Is this chip truly
"custom" or is it a relabeled Z80 support chip?
Thanks.
Rich Cini/WUGNET <nospam_rcini(a)msn.com>
- ClubWin/CW6
- MCP Windows 95/Windows Networking
- Preserver of "classic" computers
<<<< ========== reply separator ========== >>>>>
I agree, this type of shelf he described is great. i worked at a restaurant
once that used these shelves and they very adjustable and extremely sturdy. I
have seen these racks for sale at housewares stores for somewhat cheaper than
if you went to a business/restaurant supply store.
In a message dated 98-07-30 21:56:22 EDT, Sam wrote:
<< Another good rack is the Metro brand. They are a wire mesh shelf with
hollow tubing for the supports. The shelves have rings that slip over the
tubes, and the height of each shelf is set by a split plastic sheath that
clamps around the tubing and wedges into the shelf hole. They are very
sturdy and hold an enormous amount of weight. >>
Of course, you might as well buy pipe and strong wood from home depot,
drill the appropriate holes, and insert bolts in strategic locations.
That gorilla rack will probably cost more.
>
>The best computer shelves I've found were sold in the SF bay area at
Orchard
>supply hardware. The brand name was "Gorilla Rack". They're heavy,
and you
>need a hammer to put them together but the shelf supports are about 14
>guage steel angle 2 1/2 inches by an inch quarter inch pressboard on
top.
>The whole assembly weighs 50 or 60 pounds unloaded, but I've got a pc,
>it's monitor, a scanner, a laser printer, a box of cassette tapes, and
a tv
>on the one I have. It still has room and shows no signs of strain.
>
>I've seen these at Home Depot under another name.
>--
>Jim Strickland
>jim(a)calico.litterbox.com
>-----------------------------------------------------------------------
>Vote Meadocrat! Bill and Opus in 2000 - Who ELSE is there?
>-----------------------------------------------------------------------
>
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Tim Shoppa <shoppa(a)alph02.triumf.ca> wrote:
> I'm not sure exactly what a "gorilla rack" is, but the industrial
> shelf units I buy (about US$70 for 5 24"x48" shelves, 72" high, each
> shelf rated for 1500 lbs) would be hard to duplicate for less money.
> And nothing beats their ease of assembly.
A "Gorilla Rack" is the Harry Homeowner implementation of the same
idea. 72" high, three to five 18"x30" shelves I think (numbers from
memory). Available at Costco, Home De[s]pot, and Orchard out here in
Sillycon Valley, you might substitute Hechingers for the latter,
generally priced in the $45-$60 range. Comes in an expensive
cardboard box suitable for bringing home in an immaculate SUV. I've
used a few of them as well as some larger ones that I've picked up
>from a company that excessed its shipping and receiving department and
will happily confirm that (a) size matters and (b) bigger is better.
So...where are you getting yours from? I think I need a more
reliable supply.
-Frank McConnell
Upon closer inspection, it looks like the shelf with (some of) the GRiD'
< is about ready to go as well. These are those metal shelves you get at
< Target for $8 on sale.
<
< So, I guess my question is, how to others store their collection? Keep
< mind that I'm in San Francisco, and that Earthquakes are an issue. Than
Steel racks like the cheap industrial versions. Most of the shelves with
aluminum standards are too light weight. I'd suggest the stronger ones or
floor standing racks.
Allison
At 02:23 PM 7/29/98 +0000, you wrote:
> In Tim Robbins novel "Even Cowgirls" , the "Chink" quotes the Indians as
>saying they knew the white man was crazy but not so completely bonkers
>as to live in such a place when they had had demonstrations of the quakes
>powers.
Well, Quakes can be interesting, but really what they mean is your
house/office/whatever is going to be better built than elsewhere, and you
grow up with an instinctive eye for not putting breakables in precarious
places. Besides, I'd rather live somewhere that had occassional
earthquakes rather than a regular tornado, hurricane, or blizzard season...
8^)
A lot of people suggested stronger shelves, which would be a good idea
except that we're talking 7 sets of shelves (plus a whole lot of computers
that I keep promising my girlfriend will get put in there) so $50/set is a
lot of dough. Does anyone have any experience with overloading the plastic
shelves? We have some running around here, but I don't know how strong
they are.
As for starting what will end up on the floor on the floor, that would be
cool too, but I only have so much floor space (The house across the street
just went on the market -- 2700 sq ft, 4 bedrooms, yard: $695K, and no, I
don't live in a rich neighborhood.) and everybody pisses and moans as it is
about the computers strewn throughout the house already. 8^)
A lot of people suggested chicken wire or bungees to hold things on the
shelves, which prompted me to think of a low-cost solution my GF's
sister-in-law came up with: twine. Lace twine around/through the vertical
supports. Surplus phone wire or such would work too, I think.
--------------------------------------------------------------------- O-
Uncle Roger "There is pleasure pure in being mad
roger(a)sinasohn.com that none but madmen know."
Roger Louis Sinasohn & Associates
San Francisco, California http://www.sinasohn.com/
