Comments for page: 1702A EPROM Programmer

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Posted by Steve L. February 17, 2019 - 05:06 pm
Thanks Matthew, it's kind of you to make the project files available to everyone.

Regarding the 8702A versus the 1702A, I don't know much about that. I noticed back in the day that Intel had renumbered versions of the 1702A and other chips which worked with their 80XX microprocessors and I always assumed it was a marketing move to unify those product lines or perhaps that the peripheral chip specs were being tweaked to make them more appropriate for the processors. A 1975 datasheet for the 1702A shows its access time as 1us, whereas a 1975 datasheet for the 8702A shows access time as 1.3us. However, the 1702A-6 was also available, specified at 1.5us and the 1702A-2 was 0.65us.

Looking at the programming specs, the only significant difference I see is the 1702A typical Vbb supply current is 10mA but the 8702A is 0.05mA. The 1702A also has a note that Vbb must be limited to 100mA to prevent damage but the 8702A has no such note. The only current limiting I included was for Vdd at 300mA, which is specified for both part numbers.

If you find out more about the differences, please let us know.

Posted by Matthew Millman February 17, 2019 - 03:35 pm
You can do whatever you like with the images. It's going to be a completely open project i.e. gerbers, design files and source code will go up on github once I've cleaned it up, and written some documentation for it.

Actually it doesn't even need that serial port. It can use the Arduino's onboard serial-to-usb if desired (but cannot power its self from the USB).

Question for yourself: What's the deal with the 8702A? Is it a drop in replacement for the 1702A? different in some way perhaps?

Posted by Steve L. February 17, 2019 - 09:00 am
Hi Matthew, Thank you so much for your kind comments and for posting about your new, 1702A programmer project. I will add coverage of it to the survey section as soon as I can complete some much-needed infrastructure work on Tronola.com. Can I have your permission to include the photo and schematic in that?

Your project is amazingly compact with the attached Arduino, yet includes on-board generation of all the pesky supply voltages and only requires a serial interface from the PC. That should make it popular indeed! I look forward to adding a link to your upcoming project page when it's available. I hope there will be a way for readers to obtain a board or more. Please keep us posted. Hearty congratulations for your impressive achievement!

Posted by Matthew Millman February 17, 2019 - 08:23 am
Hi Steve

I have another 1702A programmer to add to the chorus of designs already now there

(schematic and piccy):
http://xpander.mattmillman.com/files/linked/c1702topbottom.jpg
http://xpander.mattmillman.com/files/linked/c1702programmer.pdf

For the most part it's not based on yours but this page has been my go-to for the last year while I've worked on it.

Just successfully read/wrote my first EPROMs with it today.

I do very much appreciate the effort you've gone to writing all of this up. It would have been a lot more difficult without this. I will have a project page for mine in due course...

Posted by Va3qe February 03, 2019 - 02:37 pm
Yes it is running DOS 6.22 natively (from a bootable CDROM. I sent you an email with more details.

Thanks for you offer to help.

Posted by Steve L. February 03, 2019 - 01:28 pm
Hi Va3qe, Sorry you have a problem with the project. I'll be happy to help with the debugging. I trust that DOS is running natively on the PC and not under Windows or another OS. You mention that the read LED comes on as soon as power is applied. I take it that you have the computer and the PROMPRG program running when you apply power to the PROM Programmer Hardware (PPHW), is that right? This suggests that there is a logic high on pin-16 of LPT1. Do you see +3V or more there? PROMPRG should be setting that pin LOW initially, so this is something we can troubleshoot. To facilitate that, please contact me at the email address seen after you click the About button near the top of the Home page. We'll get to the bottom of it!


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