Eprom Emulator for HP-71b

[coitboy2000]

Big thanks to the author of this eprom emulator:

https://mygeekyhobby.com/2020/07/05/eprom-emulator/

I built one this afternoon and it worked first go. I have attached a picture of the device emulating the HP Curve Fitting ROM.

I can put my $10 UV eraser away for good.

Richard

[rprosperi]

Thanks for sharing this, new to me.

Seems it will be much easier to load w/ROM images, but it's definitely a lot less portable...

[Dave Frederickson]

The description of the emulator seems to focus on firmware development. This isn't really necessary for the 71 as software development doesn't require an EPROM as it does with other systems. Also, the developer is hyping the inconvenience of erasing an EPROM saying it takes 20-30 minutes. My eraser takes about 7 minutes.

Rather, wouldn't it be more convenient to simply have a selection of EPROM's programmed with the HP ROM images instead of lugging that board around?

Dave

[coitboy2000]

(09-26-2020 05:08 PM)Dave Frederickson Wrote:  The description of the emulator seems to focus on firmware development. This isn't really necessary for the 71 as software development doesn't require an EPROM as it does with other systems. Also, the developer is hyping the inconvenience of erasing an EPROM saying it takes 20-30 minutes. My eraser takes about 7 minutes.

Rather, wouldn't it be more convenient to simply have a selection of EPROM's programmed with the HP ROM images instead of lugging that board around?

Dave

It's all just a bit a fun. The most convenient option would be to leave the HP-71b in the cupboard and use the android emulator but that's not the same

My eraser is a hit and miss thing and 7 minutes would never work consistently with it. What type of eraser do you have Dave ?

Richard

[twoweims]

(09-26-2020 05:08 PM)Dave Frederickson Wrote:  The description of the emulator seems to focus on firmware development. This isn't really necessary for the 71 as software development doesn't require an EPROM as it does with other systems. Also, the developer is hyping the inconvenience of erasing an EPROM saying it takes 20-30 minutes. My eraser takes about 7 minutes.

Rather, wouldn't it be more convenient to simply have a selection of EPROM's programmed with the HP ROM images instead of lugging that board around?

Dave

I wish there was a bit more room in the card reader bay so that a ZIF Socket could be installed on the HHP EPROM board. That would make switching out EPROMS a bit less hair raising.

[coitboy2000]

(09-27-2020 12:32 AM)twoweims Wrote:  

(09-26-2020 05:08 PM)Dave Frederickson Wrote:  The description of the emulator seems to focus on firmware development. This isn't really necessary for the 71 as software development doesn't require an EPROM as it does with other systems. Also, the developer is hyping the inconvenience of erasing an EPROM saying it takes 20-30 minutes. My eraser takes about 7 minutes.

Rather, wouldn't it be more convenient to simply have a selection of EPROM's programmed with the HP ROM images instead of lugging that board around?

Dave

I wish there was a bit more room in the card reader bay so that a ZIF Socket could be installed on the HHP EPROM board. That would make switching out EPROMS a bit less hair raising.

I agree. I remove the HHP carrier each time to swap eproms but break into a sweat each time I remove and re-install it.

[Dave Frederickson]

(09-27-2020 12:06 AM)coitboy2000 Wrote:  My eraser is a hit and miss thing and 7 minutes would never work consistently with it. What type of eraser do you have Dave ?

It's a Walling Dataerase II, without the timer. Looks like there may be 16 in stock here.
https://www.btw-electronics.net/product/...araceii/8/

Supposedly it has a higher output tube.

Dave

Edit: Sylvain found this article on EPROM erasure time.
https://goughlui.com/2016/09/11/experime...-lamp-sun/

[avrkris]

(09-26-2020 05:08 PM)Dave Frederickson Wrote:  The description of the emulator seems to focus on firmware development. This isn't really necessary for the 71 as software development doesn't require an EPROM as it does with other systems. Also, the developer is hyping the inconvenience of erasing an EPROM saying it takes 20-30 minutes. My eraser takes about 7 minutes.

Rather, wouldn't it be more convenient to simply have a selection of EPROM's programmed with the HP ROM images instead of lugging that board around?

Dave

Hi Dave, it's true that I focus a lot on the update process for EPROMs and the fact they have to be UV erased. The issue is not really the time it takes to erase (7 min vs 20min), its the fact that for each "update" you have to go through a "manual" process of: 1. extract your eprom from device, 2. UV erase, 3. re-install EPROM. I'm not that familiar with the HP-71b, so not sure how oftern you have to update / swap the EPROM content, but for other systems based on EPROMs, where you might be doing firmware development or frequent code changes (silly example could be game cartrige in a commodore, or ECU computer in a car, EPROM emulator saves you the entire hassle, you just plug it to a computer and you can have new version of EPROM in seconds without removing or swapping anything. I was working on a small single-board computer based on Z80 and the only way to update the firmware or write code for it, was to juggle the EPROMs but now I'm happy to use my new emulator.

Thanks
Kris (MyGeekyHobby.com)

[Dave Frederickson]

(09-27-2020 03:45 PM)avrkris Wrote:  Hi Dave, it's true that I focus a lot on the update process for EPROMs and the fact they have to be UV erased. The issue is not really the time it takes to erase (7 min vs 20min), its the fact that for each "update" you have to go through a "manual" process of: 1. extract your eprom from device, 2. UV erase, 3. re-install EPROM. I'm not that familiar with the HP-71b, so not sure how oftern you have to update / swap the EPROM content, but for other systems based on EPROMs, where you might be doing firmware development or frequent code changes (silly example could be game cartrige in a commodore, or ECU computer in a car, EPROM emulator saves you the entire hassle, you just plug it to a computer and you can have new version of EPROM in seconds without removing or swapping anything. I was working on a small single-board computer based on Z80 and the only way to update the firmware or write code for it, was to juggle the EPROMs but now I'm happy to use my new emulator.

Thanks
Kris (MyGeekyHobby.com)

Hi Kris,

I acknowledge that your EPROM Emulator is a nifty idea in the right application, but the 71B is not it. Most folks configure their machine once and be done with it. For experimentation the 71B software emulators do a fine job, then an EPROM can be burned. It's a similar method for the front-port EPROM's but I admit they're easier to swap.

I see your emulator on eBay in both kit and preassembled form. Nice.

Dave

[avrkris]

Dave, you are correct, there are use-cases that the emulator will really help with and others where it's not that useful. I'm not that familiar with the HP-71b calculator, but now that I've seen one... I shall be adding it to the list of "my geeky hobbies" ... just need to find one that doesn't cost $300

Kris

[Dave Frederickson]

I can part with one of mine. PM me and we can discuss options.

Dave