I have three principle references, with a possible fourth, for the HPD–12 project. One is the primary reference Ben Eater mentions. The second is a textbook on digital design I bought when I first got interested in building a computer from TTL chips. The third is a Digital book detailing the PDP–8 series. The possible fourth book is also from Digital. Besides to these books, I am referencing a variety of books on electronics. I am an electronics newbie. I have been interested in electronics for decades, but only recently got off my keester and started learning.
Ben Eater mentions Digital Computer Electronics by Albert Paul Malvino. In his initial video, Ben says he believes it is out of print. It is not. Earlier this year I ordered a copy to serve as a reference for a 6502 based project. That project morphed into my current project after I saw the Gigatron. Believing the book was out of print I did a web search and found some pages on Scribd. Looking at them I thought, “Wait, this is familiar.” I dug out my paperback copy of Malvino’s book and realized I had it.
When the project morphed, I looked for info on using TTL chips to build a computer. At the same time, I saw the PiPD–8 and did some research on the PDP–8. The Infogalactic article on the PDP–8 mentions The Art of Digital Design by David Winkel and Franklin Prosser contains several chapters on designing a PDP–8 compatible computer. At the time my intent was not to build a PDP–8 clone. I ordered the book thinking the information on designing the computer would be useful. This book has already diverted me away from Ben’s design on the clock. I’ll discuss that changes in an upcoming post.
Having decided to build a PDP–8 after playing around with a simulation of one in SimH I needed more details than the Winkel and Prosser book provides. Fortunately, there is a big PDP–8 community on the internet. Through them, I found PDP8/e & PDP8/m Small Computer Handbook (link to DEC authorized pdf) from Digital Equipment Corporation in 1972. It provides a great deal of information on the architecture including things The Art of Digital Design does not, such as the extra field bits that allow up to 32K words of memory. It is also a great resource if playing around with the PDP–8 in SimH.
The possible book is also from Digital, Computer Engineering, A DEC View of Hardware Systems Design by Gordon Bell, Craig Mudge, and John McNamara. Bell was one of the engineers behind the PDP–11 which was one of Digital’s most successful and influential machines serving as the home of Unix for much of its early development, the creation of the C programming language, and the base upon which the later VAX was built. The book is mostly about the PDP–11 family but has a substantial chapter on the PDP–8. Also of interest is Bell’s method of specifying computers which he used in an earlier book.
Next week we’ll look at my clock for the breadboard version of the HPD–12. I’ll discuss how it differs from Ben Eater’s design and why as well. I will also discuss some thoughts about its version in the final HPD–12 and building a standalone version as a workbench clock for digital experiments.