Eazy80-512 For RomWBW

Eazy80-512 is Eazy80 rev2 pc board configured with 512K RAM to run RomWBW. The design was derived from modifications to rev1 pcboard that supported RomWBW.

This configuration of Eazy80 replaces the standard 128K RAM with a 512K RAM and populate the 74HCT32 under the RAM chip. The 74HCT32 is part of the memory bank controller that partition the 512K RAM into 16 banks of 32KB. The 4 outputs of 74HCT32 are bank selects that drive the 4 high addresses of 512K RAM so the low 32K of Z80 addresses (0x0-0x7FFF) is mapped to one of 15 banks. When high 32K of Z80 is accessed, it always maps to the highest bank, bank 0xF, of 512K RAM. The bank register is controlled by 4 discrete outputs of channel C of PIO, PC0, PC1, PC2, PC6.

Original schematic is combination of both glue-less 128K configuration and 512K RomWBW configuration. It is confusing, so it is simplified below:

Schematic of Eazy80 for 512K RomWBW

Gerber photoplots

Bill of materials

ROM monitor for modified Eazy80 for 512K RomWBW

Eazy80-512 disk image. This is created using “buildez512.cmd” under Source subdirectory of RomWBW.

Hex file for Eazy80-512 64K ROM that contains compressed RomWBW. This ROM program will decompress RomWBW and start RomWBW. Click this link for detailed description

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Note: Eazy80-512 is now fully supported by RomWBW rev3.5 dev 103. The files below are no longer needed. Retain for archival purpose

Modification to RomWBW HBIOS.asm to accommodate Eazy80_512K banking scheme

Modification to RomWBW's SD.asm to accommodate different IO address.

SD card image for Eazy80 for 512K RomWBW

Eazy80_512K SD image is generated using “buildEAZY512.cmd” which invoke the “build.cmd” in “Eazy512” directory under RomWBW\Source. This zipped file contains the collection of .cmd and files needed to make Eazy80_512K SD image