Z80 EPROM programmer - any Z 80 system with static RAV can be used to program 2716 EPROVs

Z 80 EPROM programmer elektor january 1984 Careful manipulation of the WAIT input of the Z 80 is what enables this little circuit to fulfil the particular conditions that have to be met to pro- gram an EPROM in situ given the unusual timing of the control signals of this processor. B. Barink any Z 80 system with static RAV can be used to program 2716 EPROVs Figure 1. This is the timing diagram for the Z 80 control signals during read and write cycles. It is notable that there is a significant time delay between the appearance of MREQ and WR, whereas MREQ and RD appear simultaneously. A wait circuit is used to set the WAIT line "low" as soon as the EPROM is addressed, even during a write cycle. In order to program a 2716 EPROM there are several conditions that have to be met. The OE (Output Enable) pin must be "high", the levels on the address and data lines must be stable, the potential on pin Vpp must rise from 5 V to the programming voltage of 25 V and finally, the CE (Chip Enab...