There’s a corner of vintage/retro computers universe that doesn’t receive much attention and thats the suped 6502 machines based on the 65816 micoprocessor. The 65816 can be described as a 65C02 on steroids.
ULA’s are given their final logic configuration while still in their final stages of semiconductor manufacture and means it can take many weeks or even months for them to ready for use. This makes for a very cheap chip but any mistakes in the logic design would mean you had to scrap the ones you’ve just made and start again, adding cost and delay to your project. They lacked the flexibility of being programmable at point of printed circuit board assembly. But not so with Program Logic Array IC’s (PLA). PLA’s would be “blank” until they were needed and could be used on many different products. The PLA is an early example of field programmable chips.
The Signetics 82S100 PLA chips used in early Commodores and would be later replaced by their own design MOS 906114-01.
The success of Commodore was in part due to their business structure. They we very much a vertically integrated business which means they designed and made almost everything in their own factories. Making their own semiconductors by buying MOS Technology in 1976 was vitally important to that success. But not everything would be perfect with this setup.
Unfortunately as documented else where online, the semiconductor process used for MOS’s versions of PLA’s would eventually cause these chips to fail. The C64 PLA’s were reportedly contaminated with boron whilst being made at MOS’s semiconductor fabrication site.
Now fast forwarding to the present, finding direct replacements for this PLA is almost impossible but today there are many alternative and replacement C64 PLA out there. Here’s some I know of: PLA20V8, SuperPLA, RealPLA, PLAnkton, ezPLA, PLAdvanced, Ultimate PLA. If you know of any more drop me a line and I’ll add them to this list.
We’ll start with Marek over at his ezContents blog with has several good write ups on the C64 PLA and check out his Altera EMP7032 CPLD solution:
I acquired a pair of Apple IIe’s some time ago which could need some retro TLC. Looking at them brought back some nice memories, the Apple II was the first computer I learnt to repair way back in the early 1980’s.
So before I jump in, I thought I would check out what repair documents are on the web and brush up my knowledge. So here’s a quick list of what I found.
I find it quite amazing that computers which are still a relatively new technology now need to have their history told and recorded, so their early discoveries and examples are available for future generations to admire. I found these interesting reads
I’ve got a Commodore C4 in my collection that doesn’t have an original power supply (PSU) so whilst I could just use a C64 from one of my other machines I thought I would investigate what DIY replacements are out there. So below is a short list of C64 PSU’s DIY builds I’ve found so far:
It’s true to say that devotees of retro computing like myself are well supported for media content on the web. After visiting personal blogs and archive sites, YouTube is somewhere I like to find new content.
Below is a list of the YouTube retro computing channels I like to follow.
If you have a favourite channel that’s not listed drop me a comment and I’ll update my list.
I first encountered Elektor in the early 1980’s, probably around 1983. I remember going to our towns main library to read the latest edition (along with other electronic magazines of the time). I enjoyed reading it so much I would take out a subscription to it around 1986 and have been a subscriber ever since.
As well as Elektor I would also read Wireless World, Everyday Electronics, Practical Electronics, Electronics Today International and Electronics Magazine (from Maplin). I read all of them during those days and they definitely help educate me on electronics. I think I subscribed to most of them at one point or another. But one by one they stopped being published or merged and apart from Practical Electronics (which merged with Everyday Electronics) none of them exist today. Which is really sad.
Apart from being an avid reader of Elektor I also had the privilege of writing for the magazine on several occasions.
In 2005 I wrote three articles on the latest in microcontrollers, the arrival of the 32-bitters. In one these wrote about a design based on a NXP ARM and called it “ARMee”. I believe it was one of the very earliest articles, if not the first, on ARM microcontrollers to be published in a mainstream magazine.
The ARMee would go on to feature in other authors projects, a DCC model train controller project spings to mind. I would also go onto to write about the Raspberry Pi for the magazine.
The celebrate its 60th year, Elektor has published a special edition of the magazine which features articles about its 60 years and remembers many of the projects it published over the years. I very pleased to say my ARMee project got a mention on page 64.