Upgrading the EA PC Controlled EPROM Programmer (Sep/Oct 1993) to support 27512, 27010 and 27020 EPROMs. These mods allow this aging, yet ever popular EPROM programmer to handle the three newest types of EPROM with ease. Although you will need to re-write your software, the modifications are rather minor as all the alogarithms are already present - the overall data size being dealt with simply changes. ----------------------------------------------------------------- Mods for 27512: This is a simple modification that requires only one new DPDT toggle switch. Label this switch "27512/Other". The software will need to be re-written to work with 64K-sized chunks of data and use the correct programming alogarithm. Modification sequence: Disconnect pin 1 of the 28 pin socket. Connect pin 1 to the common of pole 1 of the new toggle switch. Connect the old wire (that used to go to pin 1) to the 'other' side of pole 1. Connect the "27512" side of pole 1 to A15 (Pin 5 of U4). Disconnect pin 22 of the 28 pin socket. Connect pin 22 to the common of pole 2 of the new toggle switch. Connect the old wire (that used to go to pin 22) to the 'other' side of pole 2. Connect the '27512' side of pole 2 to VPP-L. The software programing sequences required to access the 27512 are the same as those used when accessing a 2732 - i.e. VPP must be low during a verify, Whilst using a 27512, set the new switch to '27512'. Set the 28 pin switch to '256'. I prefer to re-label this switch as '256/512'. Whilst using any other type of 28 pin EPROM, set the new switch to 'Other'. ----------------------------------------------------------------- Mods for 27010 & 27020: I suggest one gets the 27512 mods working first, as this is a much harder job; however the 27512 mods aren't actually _required_ for this mod to work. Fit a new 32 pin ZIF socket somehow. (Anyone care to make a new front PCB panel with 3 ZIF sockets?) Wire pins 4-23 of the new socket to pins 2-21 of the 28 pin socket. Wire pins 25-28 of the new socket to pins 23-26 of the 28 pin socket. Wire pin I of the new socket to VPP-H. Wire pin 2 of the new socket to A16 (U4 pin 3). Wire pin 3 of the new socket to A15 (U4 pin 5). Wire pin 24 of the new socket to OE-bar (U2 pins 11 &l 2). Wire pin 29 of the new socket to A14 (U4 pin 6). Wire pin 30 of the new socket to A17 (U4 pin 2). Wire pin 31 of the new socket to PGM-bar (U2 pin 10). Wire pin 32 of the new socket to pin 28 of the 28 pin socket. The '28 pin' switch and the 'Other/27512' switch are 'out of circuit' when the 32 pin socket is in use, and can be set either way without affecting anything. Software-wise, the 27010 & 27020 use the same alogarithm as the 2764 and 27128 - i.e. implements dedicated PGM and VPP pins. Software needs to be modified to work with 128k & 256k sized chunks of data. These mods also allow the reading of most 1MB and 2MB flash chips such as those found on PC Clone Pentium motherboards! Writing to these chips should also be possible, as long as they are +5V programmable, but I have not tried it. The Vpp should be set to 'off' for these chips, and the Vcc should be left at 5V. ----------------------------------------------------------------- Further thoughts: 27040: Most likely uses the same technique as the 27256 to squeeze an extra address line into the same number of pins. Would require another switch wired up to do the same thing the '28 pin' switch does now, but with pin 31 and A18 (U4 pin 4) in mind. Could possibly use the same technique as the 2732 and 27512, however, but is less likely (the 27080 probably would do that). Untested theory only, I have no firm references to back this guess up. Does such a device even exist? Trial at your own risk!