How schmick will these 4116 devices make my Z80 computer look? - Page 1
Forum section: electronics / general

author: wilfred
author_rank: Super Contributor
timestamp: March 31, 2018, 05:37:02 pm
content: /.

author: bd139
author_rank: Super Contributor
timestamp: March 31, 2018, 05:39:39 pm
content: Never seen yellow ones. Are you sure they are DRAMs?

author: james_s
author_rank: Super Contributor
timestamp: March 31, 2018, 06:00:57 pm
content: Hey cool, I actually have a few just like that, when I first came across them I thought they were resistor networks, but looking closely they are RAM. Really the epoxy could be any color one wanted, I'm not sure why black is so universal. Uniquely colored ICs could be a brand trademark.

author: RoGeorge
author_rank: Super Contributor
timestamp: March 31, 2018, 06:06:05 pm
content: Those are resistor arrays, why do you need so many on a Z80 board?

author: mariush
author_rank: Super Contributor
timestamp: March 31, 2018, 06:10:01 pm
content: Ugh all I can see is those traces that don't use 45 degree angles.And I probably would have made tiny circuit boards to put each chip and the decoupling capacitor on its own board and make simms and save board space (and have the traces on the circuit board in straight line practically)

author: daveshah
author_rank: Unknown
timestamp: March 31, 2018, 06:10:54 pm
content: I think these could easily be resistor arrays, Bourns seemed to use the 4116 part number too. Definitely measure before soldering them all...https://www.ebay.co.uk/itm/Bourns-4116R-1-103-Qty-of-20-per-Lot-16-PIN-DIP-RES-NET/132210357610

author: bd139
author_rank: Super Contributor
timestamp: March 31, 2018, 06:38:31 pm
content: Yes. Definitely Bourns resistors. They're all labelled in that format!

author: Benta
author_rank: Super Contributor
timestamp: March 31, 2018, 07:30:17 pm
content: Yep, resistor arrays, 1 kohm.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: March 31, 2018, 07:36:34 pm
content: Is it April Fool's already over there?I got these babies for my 64https://www.ebay.ca/itm/GOLD-CERAMIC-NEC-D41256D-DRAM-256Kx1-120ns-Memory-USED-PULLS/112836024695?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649Those look cool!

author: TerraHertz
author_rank: Super Contributor
timestamp: April 01, 2018, 10:59:57 am
content: Ignore the doubters saying they are resistor arrrays. You should solder them in to check they work. Just because they look exactly like Bourns R-packs, value 1K, means nothing.

author: rdl
author_rank: Super Contributor
timestamp: April 01, 2018, 04:03:13 pm
content: I made a few boards back in the day using rub-down strips and patterns. I quickly learned that the shortest distance between two points is a straight line.

author: james_s
author_rank: Super Contributor
timestamp: April 01, 2018, 05:15:13 pm
content: Interesting, apparently my initial assumption about the ICs I have being resistor arrays was correct, like the OP here I looked at the part number and then thought they were DRAM.I'm not aware of any reason ICs couldn't be made any color one liked, opto couplers are often white, as far as I know the packaging is just epoxy. As long as it's opaque to light it shouldn't matter.

author: RoGeorge
author_rank: Super Contributor
timestamp: April 01, 2018, 05:37:59 pm
content: Black is better for heat dissipation.Even if ICs would be available in all the colors, then colored ICs wouldn't be cool any more, which will self defeat the whole idea.http://www.ebay.com/bhp/model-paint-kitThose ^ are oil based colors, so they are meant to be mixed with oil snake only, or else!

author: Benta
author_rank: Super Contributor
timestamp: April 01, 2018, 06:46:18 pm
content: Black epoxy is used, because the die of most ICs and discretes are light sensitive. It's much easier to use one epoxy, than to try defining which parts could eventually work with colored epoxy.The exception is certain types of optocouplers, where the reflective properties of white epoxy are desired, due to the internal construction.

author: rdl
author_rank: Super Contributor
timestamp: April 01, 2018, 08:37:25 pm
content: An alternative would be to paint the chips in colors, but I doubt there would be enough people willing to pay the extra cost to make it worth doing. It's hard to say though, considering the ridiculous stuff some people do to add bling bling inside their PCs.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 01, 2018, 09:40:00 pm
content: Quote from: Benta on April 01, 2018, 06:46:18 pmOne best selling single board computer had light sensitivity problems when they changed one of the chips to a bare die version. The fix is a dab of opaque epoxy. (Albeit in the picture, with the addition of a "math coprocessor", it's not a "single board" computer anymore...)

author: bd139
author_rank: Super Contributor
timestamp: April 01, 2018, 10:58:17 pm
content: I had some fun with that. Shooting my camera flash at the thing would result in a core dump or hang

author: Cerebus
author_rank: Super Contributor
timestamp: April 02, 2018, 01:41:25 am
content: Quote from: wilfred on April 01, 2018, 11:55:13 pmYou do yourself a disservice. It was pitched just about right for an April fool.

author: glarsson
author_rank: Frequent Contributor
timestamp: April 02, 2018, 01:47:05 am
content: Quote from: wilfred on April 02, 2018, 12:00:23 amWhy? I know of one manufacturer who bought these early DRAM chips from several manufacturers and batches. They were then mounted mixed, at random, in an attempt to spread out the supply disturbances caused by many chips activating at the same time.

author: james_s
author_rank: Super Contributor
timestamp: April 02, 2018, 10:13:28 pm
content: Quote from: glarsson on April 02, 2018, 01:47:05 amHm I'd have thought that would be more likely to cause signal integrity issues. Has anyone ever compared chips from different manufactures and batches and determined whether either scenario is really an issue?

author: glarsson
author_rank: Frequent Contributor
timestamp: April 02, 2018, 10:34:19 pm
content: Quote from: james_s on April 02, 2018, 10:13:28 pmWhy?Case 1: All memory chips change output state after ~100ns. Data is latched at 120ns.Case 2: Memory chips change output state after ~80ns to ~110ns. Data is latched at 120ns.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 03, 2018, 12:27:12 am
content: Quote from: james_s on April 02, 2018, 10:13:28 pmPC builders often say to not mix even different batches of DDR with the same part number across multiple channels.

author: james_s
author_rank: Super Contributor
timestamp: April 03, 2018, 03:20:46 am
content: Quote from: wilfred on April 02, 2018, 11:27:35 pmIt's hard to even tell. I've heard people say wackier stuff that they were dead serious about.

author: glarsson
author_rank: Frequent Contributor
timestamp: April 03, 2018, 07:41:19 am
content: Quote from: wilfred on April 02, 2018, 11:27:35 pmNo joke. However, it was not designed to be built that way. Reliability problems found during manufacturing required a fix and this was the fix that worked. If was only used for this product. Note that this happened in the early eighties, way before common use of circuit simulation and CAD systems.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 03, 2018, 02:42:33 pm
content: Quote from: glarsson on April 03, 2018, 07:41:19 amBack then, I wonder how many soft memory errors that were blamed on alpha particles or cosmic rays were actually caused by electrical marginality.

author: Dr. Photon
author_rank: Contributor
timestamp: April 03, 2018, 02:58:32 pm
content: I wish we had more colored chips!So resistor packs are sometimes yellow...optocouplers white...TI sometimes painted the tops of their old logic ICs silver...Older Japanese PNP power transistors came in green....

author: glarsson
author_rank: Frequent Contributor
timestamp: April 03, 2018, 08:31:26 pm
content: Quote from: NiHaoMike on April 03, 2018, 02:42:33 pmProbably a lot.The company I worked for at time also designed and built memory cards for our systems. We had two series of memory boards; series 1 built from 64k*1 DRAM for a total of 1MB usable (32 bit wide plus ECC), and series 2 built from 256k*1 DRAM for a total of 4MB usable (32 bit wide plus ECC). All DRAM from the same manufacturer. :-) A typical system had 32 memory boards. The paranoid part was a processor on the memory controller that scrubbed the memory for bit errors. It was repeatedly accessing idle memory sections to catch bit rot before they no longer could be corrected using ECC. Cosmic rays? Marginal timing? The answer is lost in history ...