March 06, 2019 - 06:56 am|
|@Va3qe: I had a similar problem as yours. The led went on as soon as I placed the chip in the read socket. It turned out that the card I used for LPT2 was not supporting the bidirectional mode. Finally I had to reconfigure the add-on card as LPT1 and the motherboard port was set to LPT2.|
@Steve: Thanks for this great project! Yesterday I managed to program two EPROMS with character matrices for DZM 180 dot-matrix printer (a pdf with english description of this printer is available at https://historiainformatyki.pl/historia/dokument.php?nonav=1&&nrar=2&nrzesp=2&sygn=II/1/1&handle=3)
February 18, 2019 - 04:23 am|
|That was about all I'd noticed too. So likely a 1702A "compatible" device, albeit manufactured with a newer process.|
Based on those specs I cannot see any problem plugging it into my programmer!
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.
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?
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!
February 17, 2019 - 08:23 am|