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Donn Stewart
13917 Deviar Dr
Centreville, VA 20120
dstew@cpuville.com

Designing, Building, and Selling Obsolete Computers -- for Educational Purposes -- since 2004

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News and Issues

September 16, 2017: A new CPUville website

You probably noticed that I have redone the entire website. I made these improvements:

Let me know if you like it. Feel free to suggest improvements. If you find errors, or broken links, please let me know.

June 3, 2017: 8-bit processor prototype

I have finished the 8-bit processor prototype. It is working well. Here is a demo video:

Note that the processor is connected by an adapter to the CPUville Z80 computer system board, plugged into the Z80 socket. I plan to put details of the design and construction of this processor on the web site in the future.

April 7, 2017: Problem with 2K RAM ICs

It has come to my attention that some 6116 2K RAM ICs that have been shipped with the CPUville Z80 computer kits may be defective. You can test yours by running the memory test program, located at 0x0074 in the v.7 EPROM. If you believe you have a defective 6116 RAM IC please let me know, and I will send you a replacement.

March 22, 2017: A new processor

I am developing an 8-bit computer processor that I may offer as a kit.This processor is similar to the original CPUville TTL processor, with some important differences. First, it has an 8-bit data bus, and a 16-bit address bus (that is, a 64K address space), matching the Z80's data and address bus. This means it can use the same system as the CPUville Z80 computer, by plugging into the Z80 slot on the computer kit board (using a cable of course). Second, I fix some of problems with the original processor, in main, that the ALU size did not match the instruction size, preventing easy uploading of programs. Instructions on the 8-bit processor are of varying length, instead of the single size of the original processor. Also, I have strengthened some of the hardware issues, for instance, latching the controls that need to be held steady when the state changes for writing memory or ports. A kit for this processor may cost $80 to $100. Anyone interested?

November 14, 2016

hand holding an EPROM

Tiny BASIC! In discussion with another hobbyist I realized I could assemble Tiny BASIC and it would fit into the CPUville Z80 computer 2K ROM space, taking the place of the v.7 EPROM. I made a few modifications to the code to match the CPUville computer's port addresses and UART status bits, and it works fine:

screen image of tiny basic program output

This is Li-Chen Wang's original Tiny BASIC that was first published in Dr. Dobb's Journal of Computer Calisthenics and Orthodontia in May, 1976. Here is a link to a draft of the instruction manual I am preparing. If you would like the code, please email me. I can also sell you a pre-programmed EPROM with Tiny BASIC for $4.50.

Older News and Issues items moved here.