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Re: More fun with Freed Z80




 Glen Herrmannsfeldt wrote:


Other than people wanting the same socket for EEPROM or Flash,
RAM test patterns tend to depend on the address lines.

With SRAM the address and data lines can take any permutation and/or
any number of them can be inverted. Makes no difference.

As a side remark some Apple peripheral boards including the Disk ][
had unusual mapping of data/address lines on PROMS (where it DOES
matter!) to make the board routing easier and save on vias. So the
chips needed to be programmed with specially  prepared data.

One more thing: A17 line of the 512K SRAM chip is inverted on my z80 board for a simple reason: the 128K chip uses this pin as an active high chip select and I needed it to respond to the lowest 2 banks.

-Alex.