| ??? 02/20/07 20:18 Read: times |
#133358 - naw ... just use the old RS232 level shifters Responding to: ???'s previous message |
I've got two relatively low-cost programmers that "allow" you to build your own test routines. Neither of them will accomodate the pinout, nor will either provide the negative voltage. They provide higher voltages, as EPROMs might require, but no sub-GND levels.
If you just think of the ROM as operating from + and - 4.5 volts, or even +/- 5, the RS232 level-shifters will work fine. When the ROM gives you +5 it's interpreted as a "high" and when it gives you Vdd-4 volts, or lower, it's interpreted as a "low." That looks suspiciously like the RS232 levels to me, though this clearly is a PMOS device. Those parts will apparently work without any resistors or other passives, i.e. the slew-rate controls aren't needed on the receivers. RE |
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