Cromemco CDOS is a lot like CP/M and can run CP/M programs.
There were sufficient cards to build a simple CDOS system. This is an interesting system in itself but is also a stepping stone to a Cromix system.
The cards are:
- a DPU Dual Processor Card with Z80 and 68000
- a 64KZ Dynamic Memory Card
- a 16FDC Floppy Drive Controller
The DPU is overkill for CDOS but there is one very important CDOS program that is useful to the DPU: the 68000 memory test. That would prove to be handy later.
The 16FDC floppy disk controller has some handy bonus features: a serial port for a terminal and a monitor ROM running Cromemco RDOS.
A TUART can be added to provide parallel interfaces or additional serial interfaces for printers or other devices.
The RDOS Monitor version in the ROM is 2.01 which is capable of booting an operating system from a 5.25″ double density floppy disk – but not from an 8″ disk. The card itself has a 34 pin interface for 5.25″ drives and a 50 pin interface for 8″ floppy disk drives.
I connected a 40 track drive and created a disk from a CDOS image retrieved from the Cromemco GIT repository.
Continuing what had so far been a good run, the RDOS monitor came up after a few key taps (to autodetect the baud rate)and giving a b (boot) command initiated a successful CDOS boot.
I really should have stopped and had a good play with CDOS, because my lucky run came to a halt shortly after this.