Vintage Microcontrollers?

[calexanian]

While cleaning out a big bin of tubes, of what i assumed were all masked Intel 8749 micros, I found that 8 tubes of them were windowed eprom versions. My guess is when we were programming them all for the last time 20 years ago we just used programmed the development parts we had as it was a dead end product, or we got a great deal on them and whoever was programming them did not notice or care.

What would a modern tool chain even be to program a MCS-48 series chip? Are there programmers out there for a cheap enough price to play with them? It was all assembly back then. I cant even remember what format it was done in, or did we just scratch out the HEX file by hand.

Anybody have any suggestions what to do with them? Obviously I could just sell them on eBay, but whats the fun in that?
I have accumulated so many scrap parts and chips I should probably set up a little online storefront or something.  I do own some pretty memorable domain names that I am not doing anything with.

Any thoughts?

[edavid]

There's information on a homemade programmer in this thread: https://www.eevblog.com/forum/microcontrollers/simple-programmer-for-vintage-intel-mcs-48-microcontroller/

[mikeselectricstuff]

8749s are EPROM ( OTP if in non-windowed packages) - The 8049 was the mask version
A lot of the early EPROM MCUs could be programmed with standard EPROM programmers with a simple pinout adapter - not sure if this is the case for these.

[chickenHeadKnob]

Both the '49 and '51 Intel parts in windowed ceramic brazed pin packages were hugely  expensive in the first years after they came out. I remember something in the range of $50-$70 in real money back then. Too pricey to be used in anything other than prototypes. For the 8048 I think assembly is your only choice.

[james_s]

That's totally cool. I vaguely remember seeing pictures of UV erasable microcontrollers back in the dark ages but I don't think I've ever personally come across one.

[PA0PBZ]

I also have some family members waiting for an application:

[TerraHertz]

I'd have thought all commercial device programmers would still have config info for old CPUs like this. My Topmax programmer does, and that's from around 2001. See pic.

Can't recall if I ever programmed an 8749, but I did do a lot of work with Dallas DS5000's, which are 8051 compatible. I think we used a PL1 compiler.

It's tempting to think of using the old CPUs in designs if you have tubes full of them, isn't it? But then you wake up and think, no, that would be nuts. Completely unmanufacturable, pointless, and there are vastly more capable current CPU systems, like Arduino ATMega168 for $1.20 each.

Still would be sad to bin them though. I'm all in favor of keeping all such old component stock. If only for future maintenance of systems for historical interest.

[glarsson]

Are you sure it was PL/1? Intel pushed PL/M for its early micro controllers. If you used Intels development system you used assembler or PL/M.

[TerraHertz]

Yeah, I think you're right. PL/M. I don't have that code set on my PC anymore, so not easy to check. Only have the C code for the host application.

[edavid]

There was no PL/M for the MCS-48 family, it was much too primitive.  Assembly language only.

[james_s]

I have lots of one-off projects I've built out of random parts I had, vintage CPUs like this are perfect for building something like a nixie or CRT clock or some other sort of functional art. You don't have to worry about it being practical.

[calexanian]

Just looked through the series programming guide. wow we have sure come a long way.

[@rt]

For some reason I started collecting ICs recently (including CPUs, etc.)

A couple of the EEPROM pic micros aren’t supported by the PicKit II, I guess they need a relatively high programming voltage.
I got a few extra because the plan was to keep some for collection, but also use one for some retro project.

What’s the story with the plastic goo stuff on the left side?

[technix]

There was no PL/M for the MCS-48 family, it was much too primitive.  Assembly language only.

I wonder if there is any new language support for them - SDCC’s C language maybe?

For some reason I started collecting ICs recently (including CPUs, etc.)

A couple of the EEPROM pic micros aren’t supported by the PicKit II, I guess they need a relatively high programming voltage.
I got a few extra because the plan was to keep some for collection, but also use one for some retro project.

What’s the story with the plastic goo stuff on the left side?

Me too, but I usually shy away from the windowed EPROM type stuff since I don’t have an eraser.

I was half way there designing a PC/XT GPU our of a GD32F190 chip (5V Cortex-M3 @120MHz) but kind of put it on hold now, before my PC104/64 base system can achieve a boot.

[@rt]

The $20 or so eBay eraser is fine
I have done a lot with 1Mb EEPROMs using it, and it has worked every time.

Interestingly, ever since Dave’s video on PC104, which is the first I heard of it at all, I’ve taken an interest in it, and kept an eye on eBay.
No practical reason of course

[technix]

Interestingly, ever since Dave’s video on PC104, which is the first I heard of it at all, I’ve taken an interest in it, and kept an eye on eBay.
No practical reason of course

I had this legacy computer design idea for a while, however the system design is never finalized since I did not manage to come up with an appropriate bus,until I saw that PC104 video. The PC104/64 idea is a 8-bit ISA version of PC104, by removing the 40 pins corresponding to the 16-bit AT bus part while keeping the 64 pin 8-bit part intact, since my design will be effectively a clone of PC/XT, albeit with significantly different detail designs.

[@rt]

I checked eBay again tonight. None of it is cheap, and not even easy to find the actual computer part.

I should mention, just in case you did think about it.
The eBay eraser is marketed to 120 and 240 Volt countries, but I have a variac, and it is more intense at 240V.
I used it at 120 Volts AC for 20 minutes.

[calexanian]

https://www.amazon.com/Ultraviolet-Light-EPROM-Eraser-Eraseable/dp/B00AZFZHEY

Cheapest one I could find. We have an old Datarase II floating around here. worlds most annoying done beeper.

[@rt]

Yeah that’s the one. There are a heap of different sellers selling the same eraser on eBay.

[whalphen]

Those 8741 chips were pretty cool back in the day!  They are actually MCS-48 chips configured as slave processors.  I used them to manage the user interface in some instrument designs I did back in the early 80's.  The 8741 would drive the display, keypad, printer, and indicator LEDs, thus freeing the the main 8085 processor to handle higher level system management and calculations.  I used an Intel MCS development system with three 8 inch floppy drives and 64K of RAM.  PL/M could be used with the 8085 processors.  But, all the 8741 development was in assembler.  I had an 8085 emulator.  And, in a second development system, an 8741 emulator.  The 8085 code development was done on one system and the 8741 code development on the other.  That way both emulators could run at the same time making it was possible to step through and set breakpoints and debug both processors  at the same time -- one as a master and the other as a slave.  Even though I had PL/M for the 8085, I wrote the 8085 software in assembler because PL/M generated too much code for the small amounts of UV-EPROM memory in the instrument systems.

[technix]

Those 8741 chips were pretty cool back in the day!  They are actually MCS-48 chips configured as slave processors.  I used them to manage the user interface in some instrument designs I did back in the early 80's.  The 8741 would drive the display, keypad, printer, and indicator LEDs, thus freeing the the main 8085 processor to handle higher level system management and calculations.  I used an Intel MCS development system with three 8 inch floppy drives and 65K of RAM.  PL/M could be used with the 8085 processors.  But, all the 8741 development was in assembler.  I had an 8085 emulator.  And, in a second development system, an 8741 emulator.  The 8085 code development was done on one system and the 8741 code development on the other.  That way both emulators could run at the same time making it was possible to step through and set breakpoints and debug both processors  at the same time -- one as a master and the other as a slave.  Even though I had PL/M for the 8085, I wrote the 8085 software in assembler because PL/M generated too much code for the small amounts of UV-EPROM memory in the instrument systems.

Is there any modern equivalents for the 8741? Or any method to hook a (hopefully modern ARM Cortex-M) MCU on the system bus?

[chickenHeadKnob]

Is there any modern equivalents for the 8741? Or any method to hook a (hopefully modern ARM Cortex-M) MCU on the system bus?

If I recall correctly the 8042 had a key feature for serving as a slave processor. Namely a small internal  dual port RAM and 8 bit external bus access with associated flags and control to let both processors perform atomic operations on it. I don't know of any modern equivalent. To your other question about compilers available for it, I would say once you review the ISA and see how limited the code space is you would choose assembly language anyway.

[technix]

Is there any modern equivalents for the 8741? Or any method to hook a (hopefully modern ARM Cortex-M) MCU on the system bus?

If I recall correctly the 8042 had a key feature for serving as a slave processor. Namely a small internal  dual port RAM and 8 bit external bus access with associated flags and control to let both processors perform atomic operations on it. I don't know of any modern equivalent. To your other question about compilers available for it, I would say once you review the ISA and see how limited the code space is you would choose assembly language anyway.

If that is the case, That slave processor feature is what I am looking for actually. I know that some 8-bit PIC have it, but what I am looking for is a fast 32-bit microcontroller that also have it, so I can create a GPU out of it for my PC/XT clone.