Z80 Page Comment

The Einstein TC01 and further hardware developements.

Unlike many of the alternative IBM PCs of its day the TC01 did not boot up into its own version of home basic. On power up a floppy DOS disk was needed to be in its boot drive for different basic programs and other software to be loaded in. It is a simple straight forward Z80 PC run using usually it’s designed for Xtal DOS (a CP/M 2.2 clone) for compatible software.

A third party hardware attachment for the Einstein called “Speculator” could be used to emulate the Spectrum computer. From it’s CO creator and ex company MD “Trevor Brownen” I’ve been told of “ Near 100 Thousand main boards were made only 40 Thousand or so as a PC. " Of the remainder. “The machine is still used in many control site around the world in Water works, Steel mills to say but a few, they would not be recognised as such as the mother board was fitted in a metal box, with loads of EPROM, and No monitor or Keyboard.”

From the above I consider the Einstein to be shown as a no nonsense machine, uncomplicated by the manufacture’s chosen software being built into its firmware on ROM, and ideal for further development and enhancement. It’s adaptation for a controlling element for running large industrial plant shows it has an aptitude as a test bed and development machine for modern robotics that could have Z80 built processing embedded into them. It’s proven ability to emulate the Spectrum opens thoughts to it emulating other Z80 computers. A hardware adaptation that allows different ROMs to be switched in before powering up could do this. As with the Bbcbasic version for the Einstein, basic interpreters for other Z80 computers could be developed to be loaded into the Einstein from disk or via PC/Einstein communication software.

Rebuilding a Z80 computer based on the Einstein

On the web there appears many sites by people that have built their own Z80 computers or robotic devices. Many of the original Z80 8bit computers are decades old and their continuation outside emulation on the PC could depend on rebuilding hardware.

A one time complete rebuild seems a monumental task. Stand alone keyboard input and screen output add a lot of complexity and circuitry needed just for the user to access the processor. I have seen basic fairly simple wiring schematics for basic ROM, RAM and Z80 processor using a PC terminal program for keyboard input and screen output. If these circuits could be interfaced for input and output with existing old computers would this be a way which over time a new computer could be rebuilt on a modular basis?

I am asking the questions here for my knowledge is low and I wish to know in which direction to move to get up the learning curve. Could the IBM method of add in cards be applied to additional circuits for a basic Z80 processor of RAM and ROM hub that gets user import and output from another Z80 computer? Could step by step enhancements be added by simply plugging in further built circuits on to the Z80 bus system? For a beginner to become a scratch builder of Z80 processing this approach seems attractive as the first modular component built could be accessed and used by the builder. Further modular circuits on their own printed circuit boards could later be added by a standard CPU bus connection.

At the moment my Einstein is combined via a 34 wire ribbon cable with an IBM computer PC case which holds and provides power for my Einstein’s external floppy drives. With all other IBM computer components removed there is more than enough spare capacity to house experimental Z80 circuits. The case has fittings for hard drives and other PC hardware that might in the future be added for access by a Z80 CPU.

I have not yet begun building a basic Z80 processing unit. I have still yet to find a schematic for basic ROM and RAM construction of a Z80 processing unit that a beginner can use to interface keyboard and screen import/output with an existing Z80 computer. I would be interested to hear from anyone who has practicable experience for such a project and of sharing experiences with others who would be interested in the project.