![eprom programmer 27c256 eprom programmer 27c256](http://radiomuseum.co.uk/Q/e4.jpg)
Wired up the buffered control lines (CPU outputs).Īt this point all control, address, and data lines can be observed via LEDs.
Eprom programmer 27c256 manual#
Wired up all unused inputs into the ICs used for manual reset and clock.
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I want this to be isolated away from the buses.īasically, I'd rather add components than have surprises later with the memory, etc., because of inadequate high level voltages. This is because even with moderate current, high level voltage output by the 74LS244 that drives the LEDs can drop by 0.2V. I decided to stick to my current plan of a 74LS244 dedicated to each set of LEDs. Wired up the high 8 bits of the address bus and the 8 bits of the data bus.Īll can now be observed via the 16+8 LEDs. Running the first program from memory was very satisfying. I also ran out of space on my existing breadboards and had to buy several segments. The EPROM required significant investment into an EPROM programmer (or burner - I got MCUmall's GQ-4x4 v4) and an EPROM UV eraser (also from MCUmall). A 74LS32 OR gate was used to connect Z80's RD and MREQ to 27C256's CE and OE pins. This further means that I will be able to use A15 (the sixteenth address line) as a chip selector between the 27C256 ROM and whatever RAM chip I choose. This means that it's addressable via 15bit addresses. Version 4 is important because it introduces memory. version 2 - experiment with and observe machine cycles M2 (memory read) and M3 (memory write).version 1 - initial wire-up, executes NOPs, observe incrementing address.My goal here was to complete the address, data, and control buses and to add an EPROM from which to run a simple program. This is version 4 of my Z80 interfacing project.