What "non-mainstream" microcontrollers do people use? - Page 1
Forum section: electronics / general

author: i509VCB
author_rank: Contributor
timestamp: June 23, 2025, 05:53:55 pm
content: I tend to notice a lot of people will default to a few microcontroller families: STM32, nRF5x, atmega, etc... If you are willing to go to China there are things like the WCH and PY32 parts. People tend to stick to a few families of parts and don't go beyond that.I've been working on a project and I've found NXP parts are not talked about much but have worked well for me. I also do work with some TI MSPM0 parts, although I wrote embassy-mspm0 because the TI libraries are terrible lol.What other dark horse microcontroller parts do people often work with here that are less commonly discussed?

author: Gribo
author_rank: Frequent Contributor
timestamp: June 23, 2025, 07:35:05 pm
content: In the past? Intel 80186, Hitachi, various Motorola (NXP) parts. Now? MSP430. The reason people default to these common ones is that both the parts and the toolchains went through tons of refining and documentation over the previous decades. Good luck getting a debugging toolchain for the 186 these days.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: June 24, 2025, 12:41:21 am
content: Quote from: i509VCB on June 23, 2025, 05:53:55 pmNXP would not like you calling their parts "non-mainstream"The Parallax P1 and P2 parts are "non-mainstream" MCUs that have 8 cores and some unique features.

author: SiliconWizard
author_rank: Super Contributor
timestamp: June 24, 2025, 01:18:05 am
content: We can mention the XMOS chips as well, which are not exactly MCUs, though, but can be used as such (and more).More recently, I have used the CV1800B and SG2002, which are not MCUs per se (marketed as SoCs and able to run Linux, so probably qualify more as "application processors"), but I've used them as MCUs. That would be rather "uncommon", I think.But certainly the Parallax chips are pretty unconventional and probably much more rare in the field than XMOS chips. If you're looking for something very "different", that would be it.

author: 44kgk1lkf6u
author_rank: Regular Contributor
timestamp: June 24, 2025, 01:50:01 am
content: In addition to the MSP430, Texas Instruments also makes the C200. Using either of them teaches you not to confuse the octet with the byte.

author: tggzzz
author_rank: Super Contributor
timestamp: June 24, 2025, 08:32:22 am
content: As SiliconWizard mentioned, the XMOS xCORE family. Up to 32 cores/chip 4000MIPS, expandable by interconnecting chips (transparent at the software level).Highly parallel with asoftware and toolchain that makes it practical and easy to use. That's one unique feature.Another unique feature is that you getguaranteedhardrealtime operation. None of this "measure and hope you run into the worst case" rubbish. The IDE specifies the exact timing (to the clock cycle) of the optimised codebefore the code is run.Again uniquely, the core RTOS (scheduling and messaging) is implemented in silicon, not software.The overall effect is that some things you have to do in hardware in other processors can be done in software.

author: westfw
author_rank: Super Contributor
timestamp: June 24, 2025, 09:43:43 pm
content: NXP has a lot of microcontroller families.Their ARM chips are pretty "mainstream."I have a bunch of the MC9RS08-series parts that were cheap, and are probably adequate for "general purpose use." Those are definitely no longer "mainstream." (that's why they were cheap, presumably.)In theory, I have a soft spot for the 68000-like chips ("Coldfire", these days.) The 68k was a lovely architecture, and the current NXP chips seem fine. But they're really hard to justify compared to ARM chips.

author: IOsetting
author_rank: Regular Contributor
timestamp: June 25, 2025, 02:03:09 am
content: Stick to STM32 is just fine, you can find a bunch of replacement in cas another chip shortage.In mainland China GD32, AT32, CH32, PY32 are all good choices while most of the time recently I am using PY32 because they are dirt cheap and plentifuly.

author: EEVblog
author_rank: Unknown
timestamp: June 25, 2025, 03:49:51 am
content: Quote from: i509VCB on June 23, 2025, 05:53:55 pmMicrochip PIC was THE microcontroller of choice way back, but now you hear practically nothing about them. Meanwhile, they still go into a zillion items.

author: woofy
author_rank: Frequent Contributor
timestamp: June 25, 2025, 08:16:50 am
content: Quote from: EEVblog on June 25, 2025, 03:49:51 amPIC 16/18 series CPU architecture is horrible as many have said, but it doesn't matter. When programming in C all the matters is does it do the job in the time/power & price constraints. The reason for its success is the very wide peripheral options. In my opinion, no-one else comes close in a low cost micro-controller.

author: tszaboo
author_rank: Super Contributor
timestamp: June 25, 2025, 10:18:16 am
content: Quote from: EEVblog on June 25, 2025, 03:49:51 amThey had programmers for about 25 USD (no EUR back then), with evaluation board, and free IDE, that you could just download. Lot of other microcontroller families had an entry point was 10x the price for the programmer, same for the evaluation board, and you likely had to buy a license for IAR or KEIL.Today... A classic PIC16F84 is sold for 5 EUR, not a very good value.

author: tooki
author_rank: Super Contributor
timestamp: June 25, 2025, 10:22:21 am
content: Quote from: tszaboo on June 25, 2025, 10:18:16 amWell sure, because they want you to use a more recent part, likely manufactured on a more modern semiconductor process, that costs a fraction of that, yet does more.

author: JPortici
author_rank: Super Contributor
timestamp: June 25, 2025, 10:22:31 am
content: Quote from: tszaboo on June 25, 2025, 10:18:16 amwho cares, because the modern pin compatible variant with many times the memory speed and peripheral goes for a fraction of a euro.

author: woofy
author_rank: Frequent Contributor
timestamp: June 25, 2025, 01:00:55 pm
content: PIC16F84? Another reason we use Microchip, longevity. The PIC16F84 is almost 30 years old and still available, not recommended for new designs, but available.It's remembered because it was Microchips first Flash PIC along with the PIC16F83, and a descendant of the PIC16C84, an EEPROM based chip. It was a very popular device at the time, but no longer relevant.

author: pardo-bsso
author_rank: Frequent Contributor
timestamp: June 25, 2025, 03:30:59 pm
content: HS08, but it's been a couple of years since I did something serious with them (didn't have a choice of micro)

author: westfw
author_rank: Super Contributor
timestamp: June 26, 2025, 06:16:43 am
content: QuoteI don't remember that. I mean, there were were hobbyist things where you could turn a PC parallel or serial port into a PIC programmer without many additional components, but most of the actual Microchip programmers were pretty expensive.What they DID have was Parallax (the company), deciding that the chips were of interest to hobbyists and making them available in tiny quantities at low-ish prices, when most of the competing architectures would involve trying to deal with manufacturers and vendors who had very little interest selling anyone less than thousands of chips. (other vendors followed suit, but it was pretty much PIC16F84 (flash) PIC16C54 (OTP) at under $10, or $30 8051 (windowed, or with pre-programmed BASIC, or "ROMless") (presumably Microchip also had something to do with "allowing" such small vendors.)(Also, Microchip was generous with samples.)(the 2000 Digikey catalog (https://www.worldradiohistory.com/Archive-Catalogs/Equipment-Retailers/Digi-Key-2000-Catalog.pdf) has a full line of PICs and PIC programmers ("Picstart Plus does it all! Only $199!") There's a blurb that says they now have AVRs as well, but ... they're not in the catalog...) (recalling: PIC16C84 in 1993, AT90S8515/etc in 1996, PIC16F starting in 1998.)Things were pretty dire before distributors (and vendors) started automating their ordering (and warehousing?) Not to mention catching on to the "catch them when they're young and impressionable" strategy!

author: BadeBhaiya
author_rank: Regular Contributor
timestamp: June 26, 2025, 07:56:38 am
content: That reminds me, there was this arduino like thing called PICAXE back in the 90s and 2000s which ran on PIC micros. I remember lusting after a dev kit but not being able to get one as a child.

author: woofy
author_rank: Frequent Contributor
timestamp: June 26, 2025, 08:54:13 am
content: Quote from: BadeBhaiya on June 26, 2025, 07:56:38 amIts still available:https://picaxestore.com/

author: brucehoult
author_rank: Super Contributor
timestamp: June 26, 2025, 09:41:19 am
content: Quote from: BadeBhaiya on June 26, 2025, 07:56:38 amI think that's exactly just a PIC18F25K22 preloaded with a UART bootloader and BASIC interpreter.

author: EEVblog
author_rank: Unknown
timestamp: June 26, 2025, 10:48:27 am
content: Quote from: brucehoult on June 26, 2025, 09:41:19 amYes, the PICaxe and the BASIC Stamp were the Arduino of the day, they were huge. Being able to download your program via a serial connection was ground breaking, back when you needed a compiler and a programmer.

author: EEVblog
author_rank: Unknown
timestamp: June 26, 2025, 10:52:52 am
content: Quote from: tszaboo on June 25, 2025, 10:18:16 amNot back ion the early PIC days, the PICstart was actually pretty expensive, but still cheaper than other brand micros.I used a Australian Newfound Electronics WARP-13 programmer, and that was the defacto standard low cost programmer in Australia back in the day.The thing that really made the PIC popular was that it was the first re-programmable micro (PIC16C84), no OTP or EPROM required. It used EEPROM. Flash came later in the 16F84.So Microchip absolutely owned the quick turnaround re-progammable microcontroller space that we take for granted these days. The ability to just download your code, try it, fix bug, download a new version in seconds was revolutionary.

author: EEVblog
author_rank: Unknown
timestamp: June 26, 2025, 10:56:18 am
content: Quote from: woofy on June 25, 2025, 01:00:55 pmYes, Microchip are the best at longevity.I did a video on this where I recompiled and programmed an assembler design from 20 years ago, and it just worked.

author: tszaboo
author_rank: Super Contributor
timestamp: June 26, 2025, 01:39:41 pm
content: Quote from: EEVblog on June 26, 2025, 10:52:52 amI'm talking about the Pickit 2. I for sure used it about 20 years ago, and the price in the local currency was about 25-40 USD. I don't remember the exchange rate that well, but ballpark it was that much.According to Wikipedia it was introduced 2005.Not only had it ICSP, you could do some debugging with it.They also had local distributors that were selling the ICs themselves even to hobbyists.The entire ASM language reference fit on one page that you had printed out next to the only monitor you had, a CRT next to the desktop. At least that's how I remember.

author: Rafiki
author_rank: Contributor
timestamp: June 26, 2025, 03:07:50 pm
content: Wonder why no one mentioned EFM32xx series. Or is it mainstream for you?I did a lot with 8051series (Intel, Oki, Harries, NXP), Infineon C161, ATmegaXXXX, different PIC16, PIC24 and a bit PIC32, i.MX (Freescale/NXP, wouldn't say this is a microcontroller but I think they call it application processor)... But since I first digged into EnergyMicro EFM32G880 about 15 years ago with the onboard Segger J-Link on the EVA-Board I don't like to play with anything less then such 32bit ARM Cortex-M3. EFM32TGxxx, LGxxx, GG380, EFM32JG1B... all of them have very good peripherals integrated. Had astonishing well written documentation and tools (not that good anymore since Silabs but...). Was a Microchip fan before. But when I could switched from MPLAB to RowleyCrossworks J-Link debugging, this offered a new experience in terms of speed and function.Of course if size an cost are most important I still would take a PIC12xx.

author: westfw
author_rank: Super Contributor
timestamp: June 26, 2025, 08:46:56 pm
content: QuoteAn interesting point. I would have said "ARM Cortex-M: Mainstream!" But I guess there ought to be a category for "standard" CPUs (since they seem to be taking over) with unique peripherals and/or from smaller vendors.(I still don't know if the EFMs would count...)

author: westfw
author_rank: Super Contributor
timestamp: June 26, 2025, 10:13:10 pm
content: Quote~2006...The 2010 Digikey catalog lists a "PICKit 2 Starter kit" for $50 (and another one, same name, for $25 ??) (https://archive.org/details/digi-key-catalog-us-2010/page/691/mode/1up) (2006 is pretty late, compared to what we're talking about. 2010 is "post-Arduino.")At almost exactly the same time that Arduino showed up, there was also the"USB Bitwhacker"- it used a USB-capable PIC18 and a bootloader, so it plugged directly into a PC and allowed uploading code directly from a "modern" PC. Scarily similar to the Arduino in "hardware ease of use", but it lacked the simplified software abstract or a focused target audience. (Sample software was written in several BASICs, C, or assembler. It was sort-of aimed at existing PIC hobbyists, rather than a new audience (he says, with his marketing hat on, despite not having any marketing experience! (The whole phenomena of would-be "Arduino killers" is fascinating, marketing-wise. Someone should do their MBA thesis on it.))

author: EEVblog
author_rank: Unknown
timestamp: June 27, 2025, 01:14:23 am
content: Quote from: westfw on June 26, 2025, 10:13:10 pmYes, the PICKit 2 was well a truly in the era of cost cost programmers, everyone had them by then.The PICStart was the early 90's, and it was hundreds of dollars, that's why there were low cost clones like the WARP-13.The PICStart Plus was 2000.

author: Andy Chee
author_rank: Super Contributor
timestamp: June 27, 2025, 04:44:59 am
content: I regard PICs as mainstream, even if the 16F84 is years out of date in 2025.Contrast this with the 16F84's contemporary, I would regard Atmel's offerings like the AT90S2313 as non-mainstream, though today's incarnation ATtiny2313 seems to have a following that mirrors the hobbyist 16F84 former heyday.

author: EEVblog
author_rank: Unknown
timestamp: June 27, 2025, 05:23:28 am
content: Quote from: Andy Chee on June 27, 2025, 04:44:59 amThey are, we are just taking the piss because they seem to have all but vanished from the hobbyist/maker world they once dominated.

author: BadeBhaiya
author_rank: Regular Contributor
timestamp: June 27, 2025, 08:09:27 am
content: To be fair, even AVRs which have had been more common in the hobbyist world in the form of Arduinos have all but vanished lately. Its all the ESP8266s and ESP32s now with WiFi and Bluetooth which dominate the hobby scene.Its weird, hobbyists in the past preferred AVRs because of its relatively simple architecture and simple peripherals (timers and such). In the ESP world, hobbyists enjoy much more powerful peripherals but they seldom use them

author: woofy
author_rank: Frequent Contributor
timestamp: June 27, 2025, 08:36:35 am
content: I had one of those early PICStart kits, still have the CPU from it:https://www.eevblog.com/forum/vintage-computing/before-pickit-there-was-picstart/msg3530400/#msg3530400

author: m k
author_rank: Super Contributor
timestamp: June 27, 2025, 08:56:15 am
content: Quote from: EEVblog on June 25, 2025, 03:49:51 amWe had once an analog(PAL) pay-TV protected by a clipped sync pulse.Solution was 8 pin PIC.

author: Selectech
author_rank: Regular Contributor
timestamp: June 27, 2025, 12:53:20 pm
content: Used a lot of PIC chips in last 30 years, PIC16 & PIC18, but moved to Cortex-Ms about 10 years ago.Did a lot of work with various EFM32s, TG11, PG1, PG12, GG11 but now using mostly STM32s.My new designs going to STM32H562, STM32H723/743.

author: peter-h
author_rank: Super Contributor
timestamp: June 27, 2025, 03:15:28 pm
content: Having gone up the hill with the STM 32F4xx over the past 5 years or so, I would simply not touch anything else, unless a) I needed way more power (and then a different system architecture may be the way to go) or b) the 5 quid price was too high (and then one is looking at a very high volume product with all the related commercial implications (e.g. is the customer creditworthy for a £1M order).But then, as I often say, this is my own business, so I need to learn new stuff like I need a hole in the headFor an employee, new stuff == bread on the table at home, and a better looking CV.The most weird chips I've used were the Atmel 90S1200, and the Hitachi H8/323. I've still got about 10k of the latter sitting there, surplus stock.

author: hans
author_rank: Super Contributor
timestamp: June 27, 2025, 03:37:10 pm
content: Quote from: EEVblog on June 27, 2025, 05:23:28 am2 years ago, I was using a PIC32MX250 for some WS2812 LED projects, must be quite non-mainstream..I sometimes do a social media search to see if people on Reddit/YouTube/Hackaday.io/etc. are posting *anything* with Microchip parts. But apart from some peoplestayingon 8-bit PICs or AVRs, I see practically zero dot zero mindshare elsewhere.Looks like everyone else has moved on to 32-bit chips, in particular STM32, Nordic, RPi Pico and ESP32.And NXP and SiLabs are not too uncommon in the more professional space.I'd argue the most non-mainstream controllers I use are STM32U5 and STM32L0/4. Mostly because they are relatively new (the U5 that is), niche and most people will prefer to buy raw horsepower over low power features. I like the challenge of doing battery powered projects.. it often requires a total system view and in-depth look how the MCU works to get a good result.

author: prosper
author_rank: Regular Contributor
timestamp: June 27, 2025, 07:25:40 pm
content: My favourite nearly-non-mainstream mcu is the STM8. It's an interesting little chip. Feels like a hybrid of the 'old skool' 8-bit MCU's, but with a modern peripheral set and driver library, and modern debug capabilities. It's not supported by GCC, and the vendor doesn't offer drivers that are fully compatible with an open-source compiler, so, getting a toolchain set up using SDCC is an excercise.I like playing with uber-cheap chinese chips. You know, the kind with basically non-existent documentation, and lotsa little quirks to 'discover' along the way. Learned how to stand up a toolchain, and developed a lot of re-usable skills. The WCH series is interesting - they have 8051s, ARMs, and a few flavours of RISC-V chips.

author: nctnico
author_rank: Super Contributor
timestamp: June 27, 2025, 08:09:25 pm
content: I think the bottom line here is to choose a part which really fits the bill (in terms of functional requirements, price, availability and software NRE costs) instead of just using what anyone else seems to be using. Some people are really vocal on forums about what they use but keep in mind that people also seek confirmation of their choices. Another issue I have spotted over the decades is that many hardware designers tend to choose cheap microcontrollers (and processors) but totally forget about the time it takes to write the software. Some of this is driven by the fact that hardware can be priced very easely while software development time doesn't seem to receive the same amount of scrutiny where it comes to costs. Last but not least, some manufacturers (like NXP) have their own support forums where people who use those parts have their support community aided by the manufacturer's product specialists. As a result those parts are not discussed on regular forums that much and may seem rarely used.

author: westfw
author_rank: Super Contributor
timestamp: June 27, 2025, 09:56:53 pm
content: QuoteBeing able to "evaluate" the vast array of available parts in order to make such a choice is a luxury that is all-too-frequently unavailable to the actual engineers.Decisions get made by people further up the food chain, who are sometimes basing their decisions on "other factors."We're already using this chip family, and have spent big bucks on tooling.We're already familiar with the recommended development environment.We trust this vendor. (There are "second sources!") (or "don't trust.")It's pin compatible with...It's part of a big family of chips, in case we guessed wrong about requirements.The hardware guys liked it (but the SW guys don't!)The Software guys liked it (but the HW don't!)We don't have time to do an "Evaluation"! Just make it work!Undue influence of sales reps, marketing departments, and advertising.Someone on the team studied this architecture when they were in Univ ("Hey! PIC32 is MIPS!")Our competitor is using ...And you know, usually it's OK. because the reality is most projects aren't that highly dependent on the deep internals.My theory is that this is why "hobbyists" and other Amateurs are so important. THEY have the time and inclination to "fiddle" with multiple chip families, and communicate their findings, and etc. Consider how much you know about the RPi "PIO" state machines vs the NXP/Freescale/Motorola "TPU", for example...I guess the smaller companies that do development help as well. It's the BIG companies where choices seem to get minimized (at least, until they're big enough to spend resources doing "nothing but evaluation.)Some big-company engineers have a hobbyist side as well, or will happily spend "less than their budgetary authority" or personal funds on "evaluation boards" to experiment with. But ... not all of them, or even most of them.

author: tszaboo
author_rank: Super Contributor
timestamp: June 27, 2025, 10:56:24 pm
content: Quote from: prosper on June 27, 2025, 07:25:40 pmThat STM8... I gave it a try. You have to ask some French company in email a license to a free compiler that only works for one year. And then you have barely any examples. It was quite frustrating and gave up in the end. I rather pay a bit more to some much more polished development.

author: EEVblog
author_rank: Unknown
timestamp: June 28, 2025, 09:06:22 am
content: Quote from: westfw on June 27, 2025, 09:56:53 pmIn a role at Thales I was the only electronics engineer in the department, so I got the chose whatever I wanted.For one project I needed 4 serial ports and wanted to implment an easy RTOS. I saw an ad for the Rabbit 2000 somewhere and it had both of those, so Rabbit 2000 it was.That's pretty obscure, but still available:https://www.digi.com/rabbit

author: westfw
author_rank: Super Contributor
timestamp: June 28, 2025, 09:19:39 am
content: Quotehow long did you have to make the decision? :-)QuoteOh! Deep research there!(I rather liked Rabbit, as long as you were content with a Z80-like architecture and 1MB (?) of memory. They had a clear target audience, and seemed good at addressing their needs. And they did "modules" before it was cool.)

author: Rafiki
author_rank: Contributor
timestamp: June 28, 2025, 09:46:49 am
content: @Selectech - may I ask why you switched to ST? I know they are cheaper but this is a pro only if you manufacture a very lot of devices. Return on invest...My experience with ST in general is not that good. Quality wise. Their promises are... Never dig deep into STM32 but hardware friends told me things about 'did not reach specification even on standard temperature' (beginning of STM32) and in datasheet well hidden port pin restrictions, ...In contrary since when I work with EnergyMicro/SiLabs I always found the support, clear structured peripherals, datasheets, AppNotes, astonishingly better than all what I saw before from many years working with Microchip. Of course I'm biased after about 15 years playing with EFM32 even for my hobby projects.

author: woofy
author_rank: Frequent Contributor
timestamp: June 28, 2025, 10:07:27 am
content: I never did try the Rabbit devices even though I was a Z80 fan boy back in the day.I've used the Intel MCS-48 series including the 8035 and the first EPROM version the 8748 before moving on to the 8031 family.The most obscure controller I've used is possibly the Dallas 87C520. I needed the speed, 33MHz and only 4 clks/instruction instead of the 8031's 12.Obscure but probably considered mainstream in its day. OTP versions are still available, if you want to pay £45 per device.

author: tszaboo
author_rank: Super Contributor
timestamp: June 28, 2025, 10:26:42 am
content: Quote from: Rafiki on June 28, 2025, 09:46:49 amI had a project with an STM32F103 (I think), it was used to have USB and CAN at the same time. CAN for communication with the rest of the system, USB for programming and debugging. So these share the same pins, but you can remap one of the ports. The PCB was made that way. But on page 76583 of the reference manual, in a footer with 8px letters it tells you that these two cannot actually be used at the same time because they share some memory space for the buffers or whatever.I had something similar with a Silabs micro recently. Every single peripheral can be mapped to every single pin, except the second I2C.

author: Selectech
author_rank: Regular Contributor
timestamp: June 28, 2025, 05:18:44 pm
content: EFM32GG11s have been and continue to be a really good part for us.Considering at some new STM32H5 & H7 parts for more serial peripherals and higher clock speed. Downside with new STM parts tends to be no bit-banding, which we've used to very good advantage with the EFM32s, but clock speed generally makes up for that.STM32G070 have become very handy for smaller embedded card projects and we use those a lot.We use JLC assembly and getting EFM32s to JLC has been problematic at times. STM32 parts generally directly available in JLC parts stock.

author: WattsThat
author_rank: Frequent Contributor
timestamp: June 28, 2025, 05:38:51 pm
content: Not to go off topic but wanted to mention that the gentleman that did the AVR instruction set and later Rabbit cores went on to clone the HP41 calculator in an FPGA. Still sells a kit to build a super-charged HP41 known as the HP41CL.HP41CL detailsDeveloper CV

author: prosper
author_rank: Regular Contributor
timestamp: June 29, 2025, 01:03:39 am
content: Quote from: tszaboo on June 27, 2025, 10:56:24 pmThat would be Cosmic. I've never bothered with it; SDCC all the way. It does have some warts, but it works well enough. Actually, by now, it's probably the most polished and rounded compiler available for STM8, warts notwithstanding.I've never had problems finding examples. Lots of various things on github, or in the nucleo/discovery board SDKs from STM. Code documentation is decent. If you set up an editor with code completion, it's pretty easy to just type something like 'spi' and scroll through the suggestions to find a register, struct, enum, macro or function you need. Its also pretty straightforward to develop bare metal style straight out of the RM.

author: EEVblog
author_rank: Unknown
timestamp: June 29, 2025, 04:40:44 am
content: Quote from: westfw on June 28, 2025, 09:19:39 amI didn't care about the architecture, C is C, I just needed serial ports and the easy to use RTOS that came with it.

author: 5U4GB
author_rank: Super Contributor
timestamp: June 29, 2025, 08:01:33 am
content: Quote from: EEVblog on June 25, 2025, 03:49:51 amIt was only popular because equivalent small-scale Arm stuff didn't exist. Luckily that's now doing a good job of displacing the PIC architecture and that other abomination, MSP430.Incidentally, you can always tell PIC and MSP430 programmers in a crowd, just look for anyone with many layers of healed-over bloody scabs on their foreheads, and possibly razor scars on their wrists.

author: tggzzz
author_rank: Super Contributor
timestamp: June 29, 2025, 08:10:35 am
content: Quote from: EEVblog on June 29, 2025, 04:40:44 amI want the RTOS scheduling and comms to be in silicon, and libraries to do useful things like USB/ethernet commswithout impacting my task's code in any way whatsoever, and the IDE to state the performancebeforeexecuting the code.I'll use whatever language enables those significant benefits.

author: brucehoult
author_rank: Super Contributor
timestamp: June 29, 2025, 08:49:33 am
content: Quote from: tszaboo on June 26, 2025, 01:39:41 pmDid it tell you which bits were which in register #3?

author: tszaboo
author_rank: Super Contributor
timestamp: June 29, 2025, 09:05:39 am
content: Quote from: prosper on June 29, 2025, 01:03:39 amI used to write assembly for AVR and PIC. Nowadays I don't have the patience to set up a toolchain. If it takes 20 minutes to do, the eval board and the company goes into the junk bin. I just want my usual libraries working out of the box.I don't think there is any amount of money a company could pay me to do programming as a job anymore. Because your coworkers are all a*hats that will start a blood feud over the order of variables in a struct or how you name them. And management wants the most ridiculous features bolted on to an already finished product, then asks you to give an estimate on how long it will take, then report on it with 15 minutes accuracy.The only reason I program something is that programming it myself in 15 minutes will cause less stress than talking to those people. Or I have a hobby project that I want to do myself for fun. Compilers are not fun.But seriously, if I can put together a developer team, where you say: "I will use camel case to name my variables" - That's OK, It doesn't matter and we don't give a F" is the normal way of communication, then maybe I will.

author: nctnico
author_rank: Super Contributor
timestamp: June 29, 2025, 09:06:24 am
content: Quote from: 5U4GB on June 29, 2025, 08:01:33 amI fully agree with 8 bit PICs (I never understood why PIC got so popular because it is so crappy both in terms of software development and the chip itself), but I don't see why MSP430 is bad. It has a flat memory architecture and the CPU has been designed to make it easy to write a C compiler for. I have done my fair share of MSP430 projects but never ran into problems. Besides the somewhat convoluted peripherals and average documentation, I don't see any real downsides to MSP430.

author: westfw
author_rank: Super Contributor
timestamp: June 29, 2025, 10:09:46 am
content: QuoteI rather liked the msp430, at least up until they added the warts for supporting more than 64k of address space. Very pdp11-like; much more so than any number of earlier chips that claimed to be pdp11-like! (Although, that makes it rather CISCy.)

author: brucehoult
author_rank: Super Contributor
timestamp: June 29, 2025, 10:42:48 am
content: Quote from: 5U4GB on June 29, 2025, 08:01:33 amPast tense for Arm. Now in embedded RISC-V is displacing both Arm (slowly) and everyone's proprietary ISAs and the remaining 8 bit. Only 8051 seems to be hanging on like a cockroach. -- tbh they're not bad for things that need no more than 256 bytes of RAM. Possibly AVR is better, but I've never heard or anyone licensing an AVR core to put inside their own ASIC, while 8051 is so old that clone designs are free.QuoteAgreed on PIC, but what is supposed to be wrong with MSP430? The built in constants are a little bit funky -- but handy -- and ALU operation destinations being onlyregoroffset16(reg)is a very limited number of addressing modes for a CISC, but one more than RISC gives you. It's not a bad trade-off to encode a PDP-11 with 16 registers instead of 8.

author: brucehoult
author_rank: Super Contributor
timestamp: June 29, 2025, 11:01:45 am
content: Quote from: tszaboo on June 29, 2025, 09:05:39 amAgreed on PIC, but it doesn't take 20secondsfor AVR, MSP430, Arm, RISC-V, Coldfire.Code:bruce@i9:~$ time sudo apt install -y gcc-avrReading package lists... DoneBuilding dependency tree... DoneReading state information... DoneSuggested packages:gcc-doc avr-libcThe following NEW packages will be installed:gcc-avr0 upgraded, 1 newly installed, 0 to remove and 16 not upgraded.Need to get 19.2 MB of archives.After this operation, 77.4 MB of additional disk space will be used.Get:1 http://au.archive.ubuntu.com/ubuntu noble/universe amd64 gcc-avr amd64 1:7.3.0+Atmel3.7.0-1 [19.2 MB]Fetched 19.2 MB in 2s (11.1 MB/s)Selecting previously unselected package gcc-avr.(Reading database ... 349679 files and directories currently installed.)Preparing to unpack .../gcc-avr_1%3a7.3.0+Atmel3.7.0-1_amd64.deb ...Unpacking gcc-avr (1:7.3.0+Atmel3.7.0-1) ...Setting up gcc-avr (1:7.3.0+Atmel3.7.0-1) ...real0m3.410suser0m0.001ssys0m0.004s

author: RoGeorge
author_rank: Super Contributor
timestamp: June 29, 2025, 11:37:56 am
content: Quote from: tszaboo on June 26, 2025, 01:39:41 pmUsed, or using?I am still using PICkit2, but not for PICs. Never liked PICs. Peripherals were not standard, too little RAM, and page swapping was a nightmare. However, I've used the PICkit 2 to program ATMEL AVR microcontrollers(with some software bridge).Meanwhile, since about 10 years ago or so, PICkit 2 was added as a supported hardware programmer by AVRdude, so PICkit 2 can now program AVR chips with zero software fuss. And can program PIC chips too.The PICkit2 programmer can also be used as a 4 bits logic probe, to generate or to visualize logic pulses.As for less used microcontrollers, Propeller 1 from Parallax was an interesting one. Very unusual. Its architecture and HDL code was open sourced some years ago. There is a Propeller 2 followup.https://www.parallax.com/propeller-2/

author: EEVblog
author_rank: Unknown
timestamp: June 29, 2025, 11:07:09 pm
content: Quote from: nctnico on June 29, 2025, 09:06:24 amPIC's got so popular because they were the first microcontroller with re-programmable EEPROM program memory, this was a game changer. The first mover advantage.And back then most people only needed a microcontroller to do fairly simple jobs, so the architecture didn't really matter much. And excellent C compilers like the HiTech C compiler existed.

author: 5U4GB
author_rank: Super Contributor
timestamp: June 30, 2025, 01:39:19 am
content: Quote from: tszaboo on June 26, 2025, 01:39:41 pmWith the 6502, the entire asm reference fit in your head, no need for a cheat sheet.Of course you were also quite a bit younger than, and better at memorising lists of mnemonics.

author: 5U4GB
author_rank: Super Contributor
timestamp: June 30, 2025, 01:52:45 am
content: General reply for the MSP430, possibly just a bad first impression from looking into something that involved one, not helped by the fact that they were trying to cram an Arm's worth of workload into a PDP11's worth of CPU.

author: brucehoult
author_rank: Super Contributor
timestamp: June 30, 2025, 02:17:53 am
content: Quote from: 5U4GB on June 30, 2025, 01:39:19 amMate. Mnemonics, sure, no problem. And registers, of course.Which addressing modes are available, and which flags are affected ... that's another thing entirely.Why doLDY abs,XandLDX abs,Yexist but notSTY abs,XandSTX abs,Y??Which instruction has only ZP and abs and nothing else, no indexing at all? And which flags does it set?Which instruction has ZP, abs, and imm and nothing else?The 6800 is almost always a much slower CPU, but my goodness it's much easier to memorise. All the accumulator instructions have imm, zp, abs, and off8,X while all the single operand RMW instructions have A, B, imm, and off8,X.

author: BrianHG
author_rank: Super Contributor
timestamp: June 30, 2025, 02:22:41 am
content: Quote from: EEVblog on June 29, 2025, 11:07:09 pm...the go to chip (PIC16C54) for every pirate CATV decoders since running them with a 20MHz crystal made them just the right speed to lock onto a north-american NTSC video signal. For a time, this was the largest use case for the PIC16C54 and helped increase Microchip's profits high enough to improve both their own and third party compilers and programmers.Hmmm, Wikipedia and google search has the wrong release date for the PIC16C54.They have a release date of 1993 for the PIC16C84, but 1998 for the PIC16C54, this sounds backwards.I remember using the first RS232-PICSTART programmer with a DOS Picasm compiler in 93. I wrote my own picstart programmer burning code to over-burn the 4MHz XT variants to run at the 20MHz HS speed. Basically, burn the Eprom 5 times in a row, then a protect burn. Worked flawlessly saving me thousands in using XT variants instead of the HS variants.

author: tggzzz
author_rank: Super Contributor
timestamp: June 30, 2025, 07:02:37 am
content: Quote from: brucehoult on June 30, 2025, 02:17:53 amYup.Never did get my head around all the 6502 addressing modes, and their limitations forced contorted thinking/code.

author: JPortici
author_rank: Super Contributor
timestamp: June 30, 2025, 07:27:34 am
content: Quote from: BrianHG on June 30, 2025, 02:22:41 amwhat sorcery is this? i never heard of it.. and i should have had as in high school our electronics teacher knew, used and discovered many such tricks

author: woofy
author_rank: Frequent Contributor
timestamp: June 30, 2025, 08:06:30 am
content: Quote from: BrianHG on June 30, 2025, 02:22:41 amI think the PIC16C54 is around 1989 vintage. It's one of Microchips first range of chips after splitting away from General Instruments.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 30, 2025, 08:55:27 am
content: Quote from: nctnico on June 29, 2025, 09:06:24 amThe PIC got popular because it was the first single-chip MCU that was affordable and accessible. The low cost and size also pushed into areas where MCUs would have been unaffordable or too big. Architecture was way down the list of prioritiesMicrochip were the first to push OTP as a solution for production - previously the only real options were maskrom, or an external EPROM on an 8051 type device. There were a few other EPROM/OTP devices around at the time, but most were viewed as development devices for maskrom. One exception was the Philips 87C51 range which included a 28 pin (also 20 maybe?) part when almost everything else was 40 pin DIP/PLC44The chips and tools were also easy to buy - back then many MCUs were only available via more specialist distributor.Compared to the 8051, the assembler was simple and easy to learn.Microchip also ran many free seminars to help users get going.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 30, 2025, 09:01:19 am
content: Quote from: EEVblog on June 29, 2025, 11:07:09 pmBefore that, it was the OTP PIC16C5x series that really kicked things off. The reprogrammable parts just made life a bit easier.One advantage of the architecture at the time was that the assembler was really easy to learn due to the small instruction set- compilers were fairly expensive back then.I did PIC assembler for many years (including 8K of very packed code on a soldered-down PLCC device) before moving to C.

author: BrianHG
author_rank: Super Contributor
timestamp: June 30, 2025, 04:32:29 pm
content: Quote from: JPortici on June 30, 2025, 07:27:34 amYup. Though you could fuse program the oscillator fuse of 20MHz HS variants to anything (HS, XT, LP, RC), even though the 4MHz XT ones were stuck as an XT, they would crash at 20MHz or only work for a day at 20MHz before becoming corrupt. Burning the eprom multiple times with the same software improved the on-chip eprom enough to function up to 25MHz. The HS variants fed at 40MHz by a TTL oscillator using my multiple burn trick would also function fine. (The XT would oscillate fine at 20MHz with the right caps and a good 5v supply.)Note I believe that the picstart programmer was not intended to be a production grade programmer.

author: BrianHG
author_rank: Super Contributor
timestamp: June 30, 2025, 04:36:07 pm
content: Quote from: woofy on June 30, 2025, 08:06:30 amI started using the PIC16C54 a few months after purchasing my Commodore Amiga A3000 (one of the first in Montreal), so my earlier date of 1993 was wrong. I started using the PIC at the end of 1990, not 93.

author: brucehoult
author_rank: Super Contributor
timestamp: June 30, 2025, 06:00:55 pm
content: Quote from: BrianHG on June 30, 2025, 04:32:29 pmCrazy.When are you doing DDR4?

author: BrianHG
author_rank: Super Contributor
timestamp: June 30, 2025, 08:28:30 pm
content: Quote from: brucehoult on June 30, 2025, 06:00:55 pmYup, got my software DDR3 controller working on altera's Cyclone IV & Max10 at 1gtps while altera claimed a maximum of 600mtps for software DDR3 controller only on Max10 or Cyclone V.If I had time, I would attempt a DDR4 controller, but, Xilinx has their own and Altera/Intel FPGAs are done.

author: SiliconWizard
author_rank: Super Contributor
timestamp: June 30, 2025, 08:37:11 pm
content: Quote from: BrianHG on June 30, 2025, 08:28:30 pmWhat about Lattice though?

author: RoGeorge
author_rank: Super Contributor
timestamp: June 30, 2025, 08:48:46 pm
content: Another less common are the FPGA specific soft-core processors, for example Microblaze from Xilinx, or Nios from Altera.

author: BrianHG
author_rank: Super Contributor
timestamp: July 01, 2025, 12:30:51 am
content: Quote from: SiliconWizard on June 30, 2025, 08:37:11 pmIf someone would donate a dev board with a DDR3/DDR4 ram chip on it and a DVI/or/HDMI video output port, I would do it. It would give me an excuse to try another clocking trick I worked out last year allowing for only a single clock domain plus 1 phase tunable clock for the ready data block alone. (My Altera one used 3 clock phases with 3 domains and a complex .sdc file. This would improve fitting/routing for FPGAs with simpler PLLs like those in Lattice and Effinix, Gowin.)Note that I heard that DDR4 is being discontinued and now everyone needs to move to DDR5.

author: brucehoult
author_rank: Super Contributor
timestamp: July 01, 2025, 12:52:34 am
content: Quote from: RoGeorge on June 30, 2025, 08:48:46 pmEvery FPGA vendor is dumping or at least deprecating their proprietary FPGA cores ... now you have MicroBlaze V and Nios V, which run the same ISA.

author: RoGeorge
author_rank: Super Contributor
timestamp: July 01, 2025, 07:15:10 am
content: Quote from: brucehoult on July 01, 2025, 12:52:34 amInteresting, I didn't follow the FPGA trends in the recent years.- Do they switched because the old Microblaze and Nios architectures were very similar/same with with the current RISC-V anyway, or it was different but they just dropped that in favor of RISC-V?- I thought old Microblaze, Nios, etc. were a minimalist design, made to occupy as little FPGA area as possible, though never looked into architecture details of Microblaze, Nios, or RISC-V. Is RISC-V architecture comparable in that aspect, FPGA area, or it is that the current FPGAs became large enough in the recent years, such that they can afford to spend more FPGA logic with a RISC-V soft core?

author: tggzzz
author_rank: Super Contributor
timestamp: July 01, 2025, 08:00:19 am
content: Quote from: RoGeorge on July 01, 2025, 07:15:10 amRISC-V has the marketplace mindshare for processors that can be extended and changed, e.g. when implemented in an FPGA. That brings many secondary technical advantages, e.g. toolchains, availability of developers, etc.In the next couple of decades I expect RISC-V will become a very serious challenger to ARM. It won't happen overnight, of course.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 01, 2025, 08:26:08 am
content: Quote from: RoGeorge on July 01, 2025, 07:15:10 amISTR the early FPGA cores were highly optimised to the vendor's specific architecture, whearas nowadays there is more space available so makes more sense to use something more standard.

author: nfmax
author_rank: Super Contributor
timestamp: July 01, 2025, 08:44:14 am
content: Inventing processor architectures and instruction sets has always been the coolest thing for aspiring digital designers to attempt. If only half - even one-tenth - of the attention had been given to the design of their peripherals...

author: tggzzz
author_rank: Super Contributor
timestamp: July 01, 2025, 09:13:24 am
content: Quote from: nfmax on July 01, 2025, 08:44:14 amYes indeed.The software equivalent is inventing a language, with implementing a compiler being close behind.QuoteYes indeed.The software equivalent is all the tooling that goes with a language, e.g. debuggers, code inspection/review.Exception: the XMOS xCORE peripherals are delightfully simple with built-in timers plus language support for hard realtime operation guaranteed by design in the IDE before executing the code. None of this "measure and pray you have bumbled across the worst case" rubbish

author: RoGeorge
author_rank: Super Contributor
timestamp: July 01, 2025, 09:38:19 am
content: Another interesting processor from some time ago was the bitslice (AM2900 familyhttps://en.wikipedia.org/wiki/AMD_Am2900). A 4 bit ALU (Arithmetic Logic Unit) that can be extended to as many bits as necessary.And another funny one was the "Industrial control unit (ICU), 1-bit microprocessor" from the CMOS family, meant to execute operations serially:https://web.archive.org/web/20170520123638/http://www.brouhaha.com/~eric/retrocomputing/motorola/mc14500b/mc14500brev3.pdfYet another rare architecture I've heard about (but never tried) was the dataflow-based execution, an out of order execution machine, driven by the available data and not by a PC (program counter). Not sure if there is any dedicated CPU for it already, or just a research curiosityhttps://en.wikipedia.org/wiki/Dataflow_architecture

author: brucehoult
author_rank: Super Contributor
timestamp: July 01, 2025, 09:44:29 am
content: Quote from: RoGeorge on July 01, 2025, 07:15:10 amMicroblaze and Nios II both come in multiple configurations using maybe 600-800 LUTs for a minimal one, up to 2000-3000 for a higher performance configuration.There are literally dozens of RISC_V cores from different people on github in those size ranges. PicoRV32, NEORV32, Ibex, VexRiscv, and DarkRISCV are among the most popular in that size/speed space.However there is also the bit-serial SeRV which implements the full RV32I subset at a lower performance level (32 cycles for most instructions, 64 for shifts and branches) using 125 LUTs on Xilinx Artix-7, 198 LUTs on Lattice iCE40, and 239 LUTs on Cyclone 10. It uses 164 FF and a block ram on all families.There is also now QeRV, which has 4 bit datapath (like a Z80 :-) ) and is 3x faster using 15% more LUTs.All the above run at least the basic RV32I instruction set, plus often configurable options for extensions such as multiply/divide, 2-byte opcodes, interrupts etc.SeRV is comparable in size to the 8-bit (and very different to Microblaze) Picoblaze.

author: tggzzz
author_rank: Super Contributor
timestamp: July 01, 2025, 09:58:57 am
content: Quote from: RoGeorge on July 01, 2025, 09:38:19 amThat wasn't a processor per se. It was a processor which was used to build processors. Intel's equivalent was the 3000 family, where the bitslices were 2 bits wide.In 1951 Maurice Wilkes invented "microcoding", i.e. using logic to step through the sequence of internal operations necessary to execute an ISA instruction. In the 60s IBM used it to implement some of the slower 360 series. In the mid 70s I unwittingly re-invented the concept, and later found the AMD2900family, and even later designed a special purpose signal processor.The AMD2900 family was used to implement many different computers, a few of which could have their ISA changed at runtime by loading different code. The High Level Hardware Orion 1.Nowadays microcoding is the basis for all x86 processors; it is the mechanism by which processors are changedafter deliveryto mitigate attacks such as rowhammer. Anybody who could change that microcode in an installed machine would be able to install more-or-less undetectable "viruses" (for want of a better term).https://en.wikipedia.org/wiki/Intel_MicrocodeQuoteThat was, by design, limited to being a process controller, for processes usually done by relay logic.QuoteThe problem with such machines is choosing the level of granularity.Arguably some of the beneficial effects can be obtained at a much higher level, in software. See, for example, some of the features of the Erlang language, and the way large high availability systems can be architected.

author: tggzzz
author_rank: Super Contributor
timestamp: July 01, 2025, 10:01:30 am
content: Quote from: brucehoult on July 01, 2025, 09:44:29 amAs always, the tool support is crucial.I first came across that with the Intel MDS80 "Blue Boxes2 in the late 70s. They were better than Motorola's equivalents, and were a major reason that x80 processors were built into many products.

author: nctnico
author_rank: Super Contributor
timestamp: July 01, 2025, 10:34:26 am
content: I agree with having tool support. Without a decent (free *) compiler, a processor stands no chance to becoming mainstream.* Come to think of it: I have been doing embedded firmware development for decades and never used a compiler which was paid for. Typically the vendors of the microcontroller would supply the compiler or I used GCC. Talks with sales people introducing new microcontrollers typically went like this: 'Is the compiler for free? If not, just go away.'

author: 5U4GB
author_rank: Super Contributor
timestamp: July 01, 2025, 11:52:23 am
content: Quote from: RoGeorge on July 01, 2025, 09:38:19 amI've still got a complete set of boards from a DG Nova somewhere that was built with 2901s. Impressive piece of engineering.

author: westfw
author_rank: Super Contributor
timestamp: July 01, 2025, 08:54:23 pm
content: QuoteAlso available from a couple (?) of vendors in 16bit-wide varieties. Eg the Cypress CY7C9101:https://www.silicon-ark.co.uk/datasheets/cy7c9101-datasheet-cypress-semiconductor.pdfcisco Systems used these relatively extensively in early routers and interface cards. Changing the ~13 high speed EPROMs when a microcode update was needed was ... lots of fun. (somewhat later, there were serial-loadable high speed microcode RAM chips instead, so microcode could be stored in a single normal EPROM, or in the image itself.)They had to given it up, since (essentially) they couldn't find enough engineers (either HW or SW) who could "think" in VLIW Microcode. (and of course, FPGAs and ASICs filled a bunch of the gaps.)

author: tggzzz
author_rank: Super Contributor
timestamp: July 01, 2025, 10:37:40 pm
content: Quote from: westfw on July 01, 2025, 08:54:23 pmDoesn't surprise me. That kind of knowledge is very valuable to the company - but only until the product becomes obsolete.Hence the company (may) pay very well for that valuable knowledge - but pay zero when the product becomes obsolete.Deciding whether or not to accept such (short term) high pay is a career choice that is valid either way - but you have to explicitly accept the consequences either way.For my own part, there are so many interesting topics in engineering, there's no way I would accept being limited to being a world expert in one transient niche!

author: Andy Chee
author_rank: Super Contributor
timestamp: July 02, 2025, 03:11:48 am
content: Quote from: RoGeorge on July 01, 2025, 09:38:19 amUsagi Electric homebrewed his UE-1 vacuum tube computer around the architecture of the MC14500

author: woofy
author_rank: Frequent Contributor
timestamp: July 02, 2025, 08:49:14 am
content: Quote from: RoGeorge on July 01, 2025, 09:38:19 amI've been aware of the MC14500B for a long time, but it was never a good fit for anything I needed to do. It required so much logic around it to make it work, and in 1976 there were much better options around.Besides, it pushed the definition of "microprocessor" to breaking point.

author: temperance
author_rank: Super Contributor
timestamp: July 05, 2025, 01:34:22 am
content: The most obscure one I ever used were the 87C751 and the 87C752. I had this dev board:https://www.ceibo.com/eng/products/ds750.shtmlIt costed a small fortune at that time. 30 Years later, I still remember the mnemonics... Although useless, I still have the dev. board. It came with a nice set of books written by Philips with some interesting application notes writing in a very decisive style without any room for confusion. Just what you need if you want to understand microcontrollers from scratch.The box also came with a handbook written by Ceibbo for the dev board itself. This book was a completely different beast because it went straight into details only people with experience would understand. (You can laugh, but what is a break point if you have never seen something like that before.) But after some weeks of trail and error I could toggle a GPIO pin.

author: brucehoult
author_rank: Super Contributor
timestamp: July 05, 2025, 01:58:48 am
content: Quote from: temperance on July 05, 2025, 01:34:22 amAppears to be 8051, which are as common as sand and are probably the 8 bit ISA that will never die.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: July 05, 2025, 04:38:51 am
content: Quote from: brucehoult on July 05, 2025, 01:58:48 amYes, google says released in 1991 and a ROM/EPROM pairing, it was notable as a move into lower pin count 8051 parts.Atmel followed ~ 1997 with theflash20 pin AT89C2051/4051/1051/1051U family.Microchip still list the AT89C4051 and smaller siblings, tho a new design might choose a AT89LP4052 part, which bumps to a 1T 8051 core.There are Asian pin-clones of the AT89C2051, the recent STC12H1K28-36I-DIP20 is the most powerful, able to fetch a 24 bit opcode in 1 cycle, and with a lot more RAM and Flash (1kR 28kF)Overall, the 20 pin STC8S003 pinout has become more popular among 8051 vendors.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 05, 2025, 08:12:51 am
content: Quote from: brucehoult on July 05, 2025, 01:58:48 amISTR those were the next step up from the OTP PIC 16C5x if you needed more space, the only other reasonably affordable (If you used assembler, C was expensive) and accessible (Available from Farnell etc.) OTP MCU at the time

author: temperance
author_rank: Super Contributor
timestamp: July 05, 2025, 11:34:13 am
content: QuoteThe 87C751 and the 87C752 are indeed 8051 derivatives, but not well known. Most people used PIC's or 8051 derivatives, like the 80C535 (537).QuoteThe dev board was indeed sourced from Farnell. It costed a small fortune and the microcontrollers were around €50 for the EPROM version.

author: westfw
author_rank: Super Contributor
timestamp: July 06, 2025, 01:46:57 am
content: QuoteThis kit?I remember when a UV-eraseable chip was very attractive... :-(

author: westfw
author_rank: Super Contributor
timestamp: July 06, 2025, 01:58:50 am
content: I don't know that something "old" that didn't become "popular" counts as that "non-mainstream."I have a few Fairchild "ACE" chips (those even have EEPROM program memory, apparently.)And a great deal of Toshiba OTP 4-bit micros.IIRC, both were "cheap" impulse purchases from eBay, along the lines of "those might be interesting to experiment with some day!" (hah!)One tends to forget just how poor "tool" support is for old, non-mainstream, chips can be.Toshiba doesn't even provide a free assembler for the 4bit chips, and their idea of a device programmer is apparently "you can build this adapter for your existing EPROM programmer and tell is that the micro is an obsolete-EPROM-type."Nowadays, we expect an IDE with simulator and debugger, at least two C compilers (at least one should be free OSSW), an RTOS port, a large set of libraries, and a <$30 "clone" programmer we can buy from Aliexpress.(From the datasheets that I managed to download before they disappeared, the 4-bit chips seem very similar to the 8bit PICs. Which I found "amusing", and which makes sense...)

author: temperance
author_rank: Super Contributor
timestamp: July 06, 2025, 02:38:38 am
content: QuoteExactly.QuoteThe topic title doesn't define the meaning of "non-mainstream". I had this box while most people were playing around with PIC's.QuoteI had an emulator for Atmel AT90S series. Cost around $600 or something. An much more capable emulator for an ARM cortex is about $10...15.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: July 06, 2025, 04:44:08 am
content: Quote from: westfw on July 06, 2025, 01:58:50 amFair point, it does count as "non-mainstream", but it is not currently in use.The actual title question is present tense, not past tense:What "non-mainstream" microcontrollers do people use?

author: RoGeorge
author_rank: Super Contributor
timestamp: July 06, 2025, 06:08:15 am
content: Quote from: westfw on July 06, 2025, 01:46:57 amNice ZIF socket!