7400 series logic availability - Page 1
Forum section: electronics / general

author: wbooth.clearscene
author_rank: Contributor
timestamp: April 18, 2017, 12:48:33 pm
content: Hi,I have a design that calls for a 74189.I tried to source the components in LS TTL, but half the chips were not available, and the 74LS189 was really expensive (from a dodgy eBay seller)So, I migrated to HC CMOS. I've found all the required chips except for the 74HC189, which I cannot find for love nor money.Does anyone know where I could source 4 (or ideally 6) x 74HC189 (or 74HC219) ?Cheers.

author: tggzzz
author_rank: Super Contributor
timestamp: April 18, 2017, 01:07:41 pm
content: So, you think your solution is a 74*189.You will get a better response if you detail your problem, and why you think a 74*189 is a solution.

author: tszaboo
author_rank: Super Contributor
timestamp: April 18, 2017, 02:01:03 pm
content: 74189 64-bit (16x4) RAM, inverting three-state outputsNot all 7400 logic is made equal. While 74HC02 will be probably made in the 22 century, most of the 7400 series is obsolete now, with no manufacturers.

author: wbooth.clearscene
author_rank: Contributor
timestamp: April 18, 2017, 03:45:10 pm
content: This is a pet project to build an 8 bit computer from 7400 series logic.

author: tggzzz
author_rank: Super Contributor
timestamp: April 18, 2017, 03:58:54 pm
content: OK.I predict you will have a flatter forehead and dents in various walls before you have finished.Or maybe I could sell you some of my random pieces of old TTL at excessively inflated prices

author: Ian.M
author_rank: Super Contributor
timestamp: April 18, 2017, 04:08:46 pm
content: So you want to build a SSI/MSI logic 8 bit processor. That's a concept that became obsolete in the late 70's so its not surprising that parts are discontinued and difficult to find forty years later.Expect to spend a lot of time and money sourcing N.O.S. parts from dodgy sellers, then testing and qualifying them to determine if they are genuine, functional, and still meet original specs.Jameco still claim to have stock of 74189, and they are more reputable than most:http://www.jameco.com/z/74189-Major-Brands-Tri-State-64-Bit-RAM-DIP-16_49883.html. However its going to be a PITA interfacing original TTL to 74HC CMOS logic - you'll probably need buffers to drive the TTL and pullups or 74HCT buffers to fix up its output levels.You've already compromised on CMOS, so why not go the whole hog and implement the processor in a FPGA?

author: tszaboo
author_rank: Super Contributor
timestamp: April 18, 2017, 05:19:06 pm
content: Quote from: wbooth.clearscene on April 18, 2017, 03:45:10 pmGetting a girlfriend/wife is a very effective way to solve these problems.

author: rob77
author_rank: Super Contributor
timestamp: April 18, 2017, 05:40:13 pm
content: no-one is making the 74189.. you can tell that by the fact the datasheets are scanned bitmapsgo back to drawing board and re-design your circuit to use a different mamory.if you're just building some retro stuff , then why not mimic that 74189 memory chip with a small FPGA or if it's slow then even with a microcontroller ?

author: grumpydoc
author_rank: Super Contributor
timestamp: April 18, 2017, 06:12:11 pm
content: Unless you really need the split data in/data out just use the smallest SRAM that you can find - likely to be 32k x 8 but you can just ignoreany data or address lines that you don't need (tie to ground).Some of the 74 series never had good availability

author: Cerebus
author_rank: Super Contributor
timestamp: April 18, 2017, 06:17:57 pm
content: Quote from: rob77 on April 18, 2017, 05:40:13 pmLeft or right?

author: Cerebus
author_rank: Super Contributor
timestamp: April 18, 2017, 06:27:52 pm
content: Quote from: grumpydoc on April 18, 2017, 06:12:11 pmI don't know the specifics of the design that the OP is using, but it's quite common for register files tosimultaneouslyread and write in the same CPU clock cycle on different clock edges and so the separate in and out lines may be necessary. I can't remember if the memory in question supports this, but quite a few of the TTL register file RAMs were dual-ported too, so you could also read and write different locations in the same cycle.

author: grumpydoc
author_rank: Super Contributor
timestamp: April 18, 2017, 07:41:40 pm
content: Quote from: Cerebus on April 18, 2017, 06:27:52 pmMouser stock the 74LS670 4x4 register file which might help

author: james_s
author_rank: Super Contributor
timestamp: April 18, 2017, 08:26:08 pm
content: I bought some 74189's from an ebay seller several years ago to repair a classic arcade game, actually I think it was more like 10 years ago. Anyway they took a while to arrive but worked just fine. You might try Jameco, they tend to have a good selection of random old ICs.

author: grumpydoc
author_rank: Super Contributor
timestamp: April 18, 2017, 08:31:46 pm
content: Quote from: james_s on April 18, 2017, 08:26:08 pmLittlediode have some 74F189's, though the £13.49 each price might make your eyes water a bit.

author: james_s
author_rank: Super Contributor
timestamp: April 18, 2017, 08:34:58 pm
content: 64 bit RAM is simple enough that it could probably be implemented with flipflops in a cheap CPLD.

author: tszaboo
author_rank: Super Contributor
timestamp: April 19, 2017, 08:17:26 am
content: Quote from: james_s on April 18, 2017, 08:34:58 pmHe can build the entire thing in a Spartan 3 FPGA. That would result in some actual usable knowledge.

author: kripton2035
author_rank: Super Contributor
timestamp: April 19, 2017, 09:52:26 am
content: just got a box of really old things from a dead electronician shop ... a full storage unit of 74xxx but sorry no 74189 !

author: westfw
author_rank: Super Contributor
timestamp: April 19, 2017, 10:00:48 am
content: I see quite a few 74xx189 on eBay for much less than the price you mentioned.http://www.ebay.com/sch/Business-Industrial/12576/i.html?_from=R40&_nkw=74+189It was never a cheap chip; I found them in the online Popular Electronics archives for about $9 each (in ~1970s dollars!)You didn't expect building a computer from SSI/MSI logic to be CHEAP, did you? There's a reason that everyone jumped on the microprocessor bandwagon!

author: chris_leyson
author_rank: Super Contributor
timestamp: April 19, 2017, 10:27:40 am
content: You could dig quite a few SN10144 256x1 static RAM chips out of an old TEK 7D01 logic analyser plus a fair amount of ECL.

author: alanb
author_rank: Frequent Contributor
timestamp: April 19, 2017, 12:37:22 pm
content: I have been on the same quest for 74LS189. I have recently bought 2 pieces from Cricklewood Electronics Ltd for £9.00 each + Vat and postage. The cost has prevented me from buying more. I have been unable to find any from a reputable source for less money.

author: Cerebus
author_rank: Super Contributor
timestamp: April 19, 2017, 01:35:21 pm
content: Quote from: NANDBlog on April 19, 2017, 08:17:26 amHe could just be doing this for fun, you know? Because it's a challenge? Perhaps he prefers soldering to coding in an HDL? Not everything in life has to have a practical or instructive outcome, otherwise the gods wouldn't have invented beer or Rugby football (or, for our antipodean friends, Aussie 'no rules' football).I'm sure Sir Edmund Hillary could have got to the top of Everest more quickly and more easily using a helicopter. But I suspect that had you suggested it to him you would have received short shrift and possibly even a black eye. Had he done so, no doubt he would have gained some actual usable knowledge of flying helicopters, but we wouldn't be calling himSirEdmund. Note that, even though it has been done many times before, many people still risk their lives to climb Everest (approximately 1 in 6 who make the attempt die*).Finally, if onewasgoing to use an FPGA, something a tad more recent that the Spartan 3 might be in order, or were you trying to change the challenge from using vintage SSI/MSI logic to using a vintage FPGA?*The risks of constructing a CPU out of 7400 series logic are less. Probably limited to the odd burnt finger and occasional agony as you step onto a dropped 14 pin DIL package with bare feet.

author: retrolefty
author_rank: Super Contributor
timestamp: April 19, 2017, 04:41:18 pm
content: Depending on the features and functions you want, as reference, I worked field service on TTL minicomputers in the 70s. There were many different manufactures, DEC, Data General, HP, Varian Data Machines, etc. They generally had a processor board around one foot square or larger, so very high chip counts. The instruction decode section is the hardest part depending on the complexity of the machine instruction set desired. Some used microprogramming (via high speed ROM) to implement decoding. Pretty large +5vdc high current power will be required.It's a very ambitious projects, but others have done the same.Good luck.

author: brucehoult
author_rank: Super Contributor
timestamp: April 19, 2017, 04:59:17 pm
content: Quote from: Cerebus on April 19, 2017, 01:35:21 pmI'll just quietly note that he'd have to have waited a while. The first helicopter landing on Everest wasn't until 52 years later, in 2005.He didn't turn up his nose at driving a regular Massey Ferguson farm tractor to the South Pole.And he flew to the north pole in a small plane (Twin Otter) with Steve Fossett and Neil Armstrong.

author: tggzzz
author_rank: Super Contributor
timestamp: April 19, 2017, 05:06:47 pm
content: Quote from: retrolefty on April 19, 2017, 04:41:18 pmAll those can be minimised by using a bit-serial implementation, at the expense of speed and with use of imagination.Or he might be able to learn from the ACC's Weeny Bitter computer, seehttp://www.smrcc.org.uk/members/g4ugm/acc.htmVol 3 issue 4 and following.

author: Tom45
author_rank: Frequent Contributor
timestamp: April 19, 2017, 05:12:17 pm
content: Building an 8 bit computer using 74xxx chips is a walk in the park compared to the MegaProcessor:http://megaprocessor.com/index.htmlIn either case these projects are a personal journey and who are we to say they shouldn't be attempting it.

author: rob77
author_rank: Super Contributor
timestamp: April 19, 2017, 05:54:28 pm
content: Quote from: Tom45 on April 19, 2017, 05:12:17 pmthat's ultra coolactually one of my childhood dreams was to build a processor from discrete transistors.. but when i was young i had no money for such a project, later i had no time for that and now, when i could spare the money and also the time.... i'm not interested in the idea anymore (shame on me for that !)

author: tszaboo
author_rank: Super Contributor
timestamp: April 20, 2017, 01:00:40 pm
content: Quote from: Tom45 on April 19, 2017, 05:12:17 pmSomeone should make a processor like that from IGBTs operating at 1000V.

author: tggzzz
author_rank: Super Contributor
timestamp: April 20, 2017, 01:57:30 pm
content: Quote from: NANDBlog on April 20, 2017, 01:00:40 pmPersonally I'd start with dekatrons; it is well worth going to see the world's oldest operating computer:https://en.wikipedia.org/wiki/Harwell_computerIt also saves wiring up front panel LEDs

author: rob77
author_rank: Super Contributor
timestamp: April 20, 2017, 02:17:08 pm
content: Quote from: NANDBlog on April 20, 2017, 01:00:40 pm1kV logic would be quite immune to noise... even during heavy lightning hitting the computer itselfunfortunately it would be immune to high clock frequencies as welland the performace would be measured in FLOPMs - floating point operations per month

author: tggzzz
author_rank: Super Contributor
timestamp: April 20, 2017, 03:08:50 pm
content: Quote from: rob77 on April 20, 2017, 02:17:08 pmThe first commercial computer I used, an Elliott 803, had a very well regarded Algol-60 compiler, 39bit words and a fastest cycle time of 575us. Yup, 2kIPS.It played music, but the higher notes were distinctly flatYou can see/hear one operating here:http://www.tnmoc.org/If you ask nicely, they will get out the circuit diagrams and discuss them with you. Yes, I have considered recasting the primitive blocks into an FPGA

author: Tom45
author_rank: Frequent Contributor
timestamp: April 20, 2017, 04:04:27 pm
content: Quote from: NANDBlog on April 20, 2017, 01:00:40 pmThe first step in the project would be to make sure your life insurance was paid up.

author: Tom45
author_rank: Frequent Contributor
timestamp: April 20, 2017, 04:09:14 pm
content: Quote from: tggzzz on April 20, 2017, 03:08:50 pmI learned programming on an Alwac 3e, a tube and drum computer with a 5ms cycle time, an order of magnitude slower than your Elliot 803. 200 ips!I've always wanted to visit Bletchley Park, but hadn't heard of the National Museum of Computing until seeing your link to it. Now I have one more reason to visit. Thanks.

author: tggzzz
author_rank: Super Contributor
timestamp: April 20, 2017, 04:14:55 pm
content: Quote from: Tom45 on April 20, 2017, 04:09:14 pmThere was an acrimonious split between the Bletchley Park Museum and TNMoC a few years ago.I haven't been to Bletchley Park Museum, and only been to TNMoC once. However, I intend to return to TNMoC since the museum staff are the best I have seen inanymuseum: they have personal experience of the exhibits and will discuss them in detail. Highly recommended.The only bad thing is that I remember using many of the exhibits

author: james_s
author_rank: Super Contributor
timestamp: April 20, 2017, 06:06:03 pm
content: Quote from: tggzzz on April 20, 2017, 04:14:55 pmThat's fascinating though, I mean getting old sucks, but for those of us who were not around when some of the really influential old stuff was in active use it's interesting to hear from those who were.

author: tggzzz
author_rank: Super Contributor
timestamp: April 20, 2017, 06:33:33 pm
content: Quote from: james_s on April 20, 2017, 06:06:03 pmIt is usually better than the alternativeQuoteI used the Elliott 803 while I was at school; it was more or less a museum piece then! I did meet the author of the Algol-60 compiler, CAR Hoare, in the 90s, though.Quite a few of the TNMoC exhibits are from the 70s/80s. The oldest computer I own is a "Fat Mac" - which I used to learn OOP with Smalltalk.

author: james_s
author_rank: Super Contributor
timestamp: April 20, 2017, 06:43:09 pm
content: I was fascinated to discover that one of the older guys I work with wrote part of the operating system for the Atari ST back in the 80s. That was an exciting time to work with computers, technological development improving by leaps and bounds, amazing new features and capabilities coming out all the time, hardware and software becoming more powerful at a crazy pace. Better graphics, better sound, faster, smoother, higher resolution, more memory, it just kept getting better and better. Then at some point it plateaued, computers got boring, new versions of software started to occasionally be worse than the version they were meant to replace, then that became increasingly common. Now I can't think of anything I do with my computer that I couldn't do nearly as well a decade ago. The array of different platforms is gone, no more Amiga, ST, drooling over Sun and SGI workstations, these days you can get a PC or a Mac, which is essentially the same, it's just not exciting anymore.

author: tggzzz
author_rank: Super Contributor
timestamp: April 20, 2017, 08:32:31 pm
content: Quote from: james_s on April 20, 2017, 06:43:09 pmAgreed. Back then there was a "pre-cambrian explosion" centered on micros. Nowadays the nearest equivalent centre on additive printing, manpower electronics, and applications enabled by very high speed ADCs/DACs. If I was starting again , I would go into genetic engineering.

author: Tom45
author_rank: Frequent Contributor
timestamp: April 20, 2017, 11:41:40 pm
content: Quote from: tggzzz on April 20, 2017, 06:33:33 pmThat's cool that you got to meet Sir Tony Hoare. His early claim to fame was developing QuickSort in 1959.

author: ebastler
author_rank: Super Contributor
timestamp: April 21, 2017, 06:39:53 am
content: Nothing wrong with building a retro design (in my book, at least). If you have a retro circuit diagram which calls for 74189s, I would definitely try and use these. Simulating in FPGA is just wrong!I'm wondering whether there has ever been a 74HC189; probably this small RAM capacity was obsolete by the time the HC series became popular. But you can easily obtain old 74LS189 chips, through ebay etc..The output of an LS TTL IC does not reliably drive a HC input (which has a switching threshold of 2.5V). So you can't simply mix and match LS and HC series in one circuit. But if you use HCT chips as the interface between them, you'll be alright: These have an input threshold matching the old LS series outputs, and provide full 5V output to match the HC series.So you could either move your complete circuit to HCT (and some LS where needed) -- not necessarily recommended, since the noise immunity will not be as good as with HC signal levels. Or you can connect HCT chips to all the 74LS189's outputs, and use HC series chips everywhere else.

author: tggzzz
author_rank: Super Contributor
timestamp: April 21, 2017, 08:49:23 am
content: Quote from: ebastler on April 21, 2017, 06:39:53 amWell,... yes but.I'd half-tempted to recreate an Elliott 803 in an FPGA, just as someone has recreated a Cray-1 in one.But I'm certainly not tempted to find all the ferrite cores used in the logic gates, nor to fill up two rooms of my house. Plus I've only got one small plane of ferrite core memory, not the double shoebox of 8192*39 (no misprint) necessary for a fully-loaded machine.

author: Moshly
author_rank: Regular Contributor
timestamp: April 21, 2017, 11:16:25 am
content: Quote from: tggzzz on April 20, 2017, 01:57:30 pmNot retro enough, how about going EM with ->http://web.cecs.pdx.edu/~harry/Relay/Or, how about just M->

author: tggzzz
author_rank: Super Contributor
timestamp: April 21, 2017, 02:31:51 pm
content: Quote from: Moshly on April 21, 2017, 11:16:25 amI think I'll stick with my earlier (almost)infinitely parallel computer.

author: Nusa
author_rank: Super Contributor
timestamp: April 21, 2017, 03:59:23 pm
content: Quote from: wbooth.clearscene on April 18, 2017, 03:45:10 pmThat's something I actually did once, as part of a Computer Science lab. Of course, it was the 1970's and 7400 series logic was fully available. Wirewrap sockets, spool of wire, hand wirewrap tool, net lists, logic probes to verify. Ended up with a single-board PDP-8 with idiot lights and toggle switches plus a UART for connecting to one of the TTY's in the room. The professor who taught that version of the class, Dave Winkel, passed away last year. One of my Dad's friends.

author: james_s
author_rank: Super Contributor
timestamp: April 21, 2017, 06:44:59 pm
content: I've always wanted to build a computer proper 70s style on a big FR4 prototype board using wire wrap, maybe a 6502 or Z80. Wire wrap sockets and pins are quite expensive though.

author: brucehoult
author_rank: Super Contributor
timestamp: April 21, 2017, 07:38:32 pm
content: Quote from: james_s on April 21, 2017, 06:44:59 pmSome friends and I built a wire-wrapped 6809 computer in 1983. I think the 6809 was a bit more of a single-chip solution than many previous chips. I recall 8 x 64 kbit DRAM, a ROM, a UART, and some kind of interface to a couple of 8" floppy drives salvaged from somewhere. I was quite proud of my clock circuit which ran the CPU at different speeds depending on what it was talking to ... the RAM was happy at 2 MHz. The ROM claimed to be a 1 MHz part but close examination of the timing diagram showed that actually it should be happy with an asymmetric clock with 0.5 us high and 0.25 us low (or vice versa) for effectively 1.33 MHz, so I implemented that. It worked :-) I think some other parts wanted a real 1 MHz. The state diagram was not that tricky.We debugged the thing and got it going in about two hours using nothing more than a dual trace CRT oscilloscope. There were two bugs: 1) the reset switch was wired NC instead of NO; 2) the UART clock divider got wired as divide-by-12 when it needed to be divide-by-13 to get a 9600 bps x16 clock to it from the 2 MHz system clock (or maybe it was 19200 x8 or 38400 x4 .. I don't remember now).Fun times.