On 9/4/23 12:17, John Heritage via vcf-midatlantic wrote:
I’m watching Adrain’s Digital Basement where he covers the Apple II clones. Was it pretty cheap to buy large enough blank EEPROMs and then copy them yourself or were the burners expensive back then?
I knew of EPROMs and how to program them from the early 80s. Worked with an Apple EPROM burner (could burn the little 256x8 PROMs). I then got a job by building an EPROM burner for my Atari 800xl via the joystick ports (lots of shifting of data). Like Jeff said get the bits in place and one shot then next. Wasn't really hard to do but keeping up with the new methods of talking to the EPROMs was a pin. Also didn't deal with the triple voltage EPROMs but almost got burner when a vendor tried to dump a bunch of TI2716s (triple voltage) EPROMs instead of the TI2516 (single voltage) EPROMs. I do recall the the 2723s were inexpensive but 2764 and above got really expensive. My friend got a DATIO burner and also had a ChipIO burner (which I still have). But I could never get to borrow the DataIO as it was always in use. So I ordered an EPROM burner kit from the back of the computer shopper. Still have that one and it still works. That was $100 well spent. I can also burn EEPROM also. :-) BTW, the 27512 was most prized for development. You just needed the correct adapter and you could bank switch the new code into the board under development. This meant you burned a portion of the EPROM, set the correct bank, tested your code and burned the next bank if code needed to be changed. When you filled the EPROM you cleaned it and went on the the next. No fussing with the entire burn and clean cycle each time. BTW, I also have the Z80 Starter kit with my Applied Microsystems Z80B CPU Emulator. Much better than burning EPROMS just change the bytes in RAM and debug with break points. :-) Maybe I'll bring it in to the CDL on the next Repair weekend Sunday. -- Linux Home Automation Neil Cherry kd2zrq@linuxha.com http://www.linuxha.com/ Main site http://linuxha.blogspot.com/ My HA Blog Author of: Linux Smart Homes For Dummies KD2ZRQ