For details see my Github page here: https://github.com/sebhc/sebhc/wiki/NAB ... ption-card
On the Github page you can download the Gerbers and ROM and compact flash images so you can build your own card. I also posted links to parts you'll need when building it yourself.
What is the RomWBW?
For details about RomWBW you can visit this page: https://github.com/wwarthen/RomWBW
RomWBW is a generic boot ROM for Z80 based computers. It is full featured and supports booting to a wide variety of CP/M operating systems with built-in support for common hardware components. It is constantly being improved opon by Wayne Warthen and is extremely well documented. I worked directly with Wayne when designing my RomWBW Option Card for the NABU and with his help we were able to make the card very robust.
The Option Card includes the following features:
- Boot to several versions of the CP/M operating system - CP/M 2.2, CP/M 3, ZSDOS, NZCOM
512K RAM
512K ROM
RS232 port via a 16550 UART
IDE interface with compact flash card (via IDE to CF adapter)
See this link for instructions on how to boot to a CP/M OS: https://github.com/sebhc/sebhc/wiki/NABU#boot-to-cpm
The compact flash has a FAT partition on it so you can copy files to/from the compact flash from a PC or Mac. On the CP/M side RomWBW includes a software utility called FAT so you can copy files to/from the FAT partition. This is a somewhat easy way to get files to your CP/M computer however it does require that you power down your NABU and pull out the card. When the cover is on your NABU this is not so easy so there's another way to get files to your CP/M computer without pulling out the compact flash. You can use the RS232 port and the RomWBW "XM" utility to transfer files via Xmodem.
You plug the card into any of the Option Card slots in the NABU and run a 40 pin ribbon cable to the Z80 CPU socket on the NABU motherboard. The Z80 CPU is moved to the Option Card. The Option Card interfaces with all of the NABU peripherals (such as the VDP and PSG) through the Z80 CPU socket on the motherboard. This gives the Option Card full control of your NABU PC. No need to remove the NABU ROM on the motherboard as it is bypassed when the Option Card is in control. There's a single jumper on the Option Card to switch between NABU mode (enabling the NABU ROM) and RomWBW mode. In NABU mode your NABU PC works just like it did before.
Fully assembled card:
Installed in a NABU Personal Computer:
Configuration jumpers:
