I have many new projects on the way that are quite a bit different from those I've published in the past.  Here's the latest project in honor of 50 YEARS OF CP/M:

A microcomputer system based on the Intel 8080!

I'll be describing the design and construction of the computer and demonstrating various BASIC interpreters from the 70s, how to get CP/M installed and running, and then showing you some of the most popular CP/M applications from the 70s and early 80s.  Below I've attached everything you need to replicate this project (or one of your own design) including schematics, board layouts, documentation, software, and source code.  This project is more suited to the advanced builder but I'm hoping it will be fun to read for everyone interested in retro-computing or considering building their own microcomputer with the 8080 or Z80 microprocessor.  You don't have to spend $10,000 on an old IMSAI or Altair.  Build your own for less than $200 that is easier to use and runs the same software.

The microcomputer system shown above has:

• Intel 8080 microprocessor clocked at 2.2 MHz
• 64K RAM, 32K Flash ROM
• Serial console port
• 128MB Flash Drive (15 logical drives of 8MB each)

I am very surprised how much can be accomplished with an 8-bit microcomputer and only KBs of RAM and MBs of disk: software development in BASIC, FORTRAN, COBOL, PASCAL, and C; Word Processing; Spreadsheets; Databases, Adventure Games.

Introduction and Design

The video below provides an overview of the design of the 8080 computer by briefly describing the most important parts of the schematic including the "shadow ROM" feature needed for CP/M.

Below are the documents and parts list that more fully describe the design:

Construction and Monitor Operation

The video below provides an overview of how the computer was constructed and demonstrates the use of the monitor program stored in the flash ROM.

Below are the documents and useful links that were demonstrated in the video:

The FLASH version of the monitor is written to the flash ROM and includes the startup routine that triggers the shadow ROM feature.  The RAM version of the monitor is used when loading the PCGET utility on the newly initialized CP/M file system.  The CPM version of the monitor runs in the CP/M TPA area for use when launching the monitor from the CP/M command line.

Useful Links:

 BASIC Language Interpreters

The video below demonstrates several BASIC interpreters that were popular in the early days of the micro computer.

The presentation file is here:  part3-slides.pdf

Be sure to check out the presentation document it may contain updates and corrections to those shown in the video.

Below are the source files used in the demonstrations.

NOTE:  If using the ASL assembler, be sure to run P2HEX using the -R option to add an offset to the HEX file.  The source files that I show loading at address 8000h use the following command:

P2HEX -R 0x8000 <filename.p>

Useful Links:

Adapting CP/M 2.2 to the 8080 Computer

The video below describes the process for adapting CP/M to the 8080 Computer.

The presentation file is here:  part4-slides.pdf

Be sure to check out the presentation document it may contain updates and corrections to those shown in the video.

Below are the CP/M 2.2 source files used on the 8080 computer.

Useful links:

CP/M 2.2 Adaptation Part 2 and Killer Apps on the 8080 Computer 

I think it is incredible how much can be done with an 8-bit microprocessor and 64K of RAM.  The killer applications of the 80s all run on the 8080 computer described in this article.  The video below proves it:

The presentation file is here:  part5-slides.pdf

Be sure to check out the presentation document it may contain updates and corrections to those shown in the video.

Below are the applications demonstrated in the video along with the four most important programming languages available on CP/M (BASIC, C, FORTRAN, and PASCAL).

Useful links:

CP/M 2.2 Internals - The CP/M File System

In the video below I spend some time discussing the CP/M 2.2 File System of which a key component is the Directory.  I also demonstrate a sector editing program I wrote for the 8080 computer that aids examining the directory and disk blocks assigned to files.

The presentation file is here:  part6-slides.pdf

Be sure to check out the presentation document it may contain updates and corrections to those shown in the video.

Below is the source code for the sector editor program used in the video:

CP/M 2.2 Internals - Upgrades, Mistakes Corrected, and more about the File System

In the video below I discuss some upgrades I did on the system software, I describe how I resolved two pesky problems that cropped up while using the system, and I provide some more information about the CP/M 2.2 file system.

The presentation file is here:  part7-slides.pdf

Be sure to check out the presentation document it may contain updates and corrections to those shown in the video.

Below are the source files for the demonstration programs shown in the video:

This has been a fun and challenging project and I am amazed at how much a small computer system like this can do, and how fast it can do it.  Although nowhere near as fast as a modern PC, I am still amazed.

As a bonus I've added a VI editor to my 8080 computer which is based on the VED editor from Manx Software Systems.  The source code for VED was originally written in C and compiled on an Apple 6502 machine.  I've modified the source code to run on CP/M 80 with ANSI terminal and keyboard codes so that it can work with Putty or Tera Term.  The VI editor below contains a nice subset of the UNIX VI commands.  It's not lightning fast but it seems to work really well on my 8080 computer.  I'll be writing a VI editor from scratch in 8080 assembly which should be much smaller and faster.  But for now this C language VI editor seems to work well for me.

By 1982 these amazing 8-bit computers were still not being given credit for all the things they could do.  Most enterprise companies still viewed the Apple, Commodore, and TRS-80 machines as "toys".  Although the personal computer would gain new and well-deserved respect when the IBM PC took over the market, I just don't think it was fair for the 8080, Z80, and 6502 to be viewed as "not ready for business".  I regularly review and retrain as part of my engineering discipline and I think all engineers should do the same to avoid becoming stale.  I recently purchased a book on computer algorithms used in computer science courses across the nation.  You are never too smart or too old to go back to the basics every now and then.  So that's what I did for this video.  Along the way, I get to demonstrate my 8080 computer as a C language development platform.

 The presentation file is here:  insertion-sort.pdf

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