On Thu, 12 Mar 1998 01:23:56 -0500 Sean Breheny writes: >At 08:10 AM 3/12/98 GMT+2, you wrote: >>Hi to all >> >>I'm looking at building a simple EPROM programmer for >>the 2716 to 27512 EPROM's (All I need for now). I'll >>probably use a PIC in there somewhere. So I was wondering >>if anyone out there knows where I can get the programming >>specs, or has them for me. I had a look around, I could >>find the pinouts but that appears to be it. There are 3 pricipal algorithms: * Single 50 ms pulse - Used only on very old EPROMs, 2716, 2732, maybe some 2764. Set up address and data, and apply a 50 ms programming pulse. * "INTELligent Algorithm" - Apply repeated 1 ms pulses until verify, then "overprogram" with a pulse 3x the total length of previously applied pulses. * Quick pulse - Apply repeated 100 us pulses until verified *at Vdd = 6V to 6.5V* Most newer devices can use either the quick pulse or the INTELligent method, the former being faster but needing adjustable Vdd. Programming voltages of 25, 21, and 12.5V are popular. I think just about all CMOS (27CXXX) EPROMs use 12.5V. Usually the voltage is marked on the chip. The 2732 and 27512 devices share the programming voltage input with the OE pin, so a more complicated switch is needed to change from program to verify mode. The others have a dedicated Vpp pin so all programming signals are TTL-level. Data sheets from any EPROM maker, e.g. AMD or Microchip, will have complete details. Finding data on the older small chips can be hard. The 27C64 is the smallest I'd recommend for new designs, even if 2K or less space is actually needed. _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866]