On Thu, Dec 26, 2024 at 9:03 PM Mike Rieker via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> wrote:
If anyone is interested
Seriously interested! I have been trying to add mass storage to my PDP-8/L since I got it in High School in the early 80s! There were only a few options then and I never encountered any for sale at a price I could approach.
I finished a Zynq thing that plugs into the back of my PDP-8/L to provide disk, tape, tty functionality. The thing actually boots and runs OS/8!
Outstanding! That's been my goal all along - boot OS/8 on an -8/L.
Anyway I made an Hackaday page https://hackaday.io/project/202048-pdp-8x2fl-enhancements
Nice photos. Would love to see more detail.
About all I had to do to get the PDP running was replace a few (half dozen or so) 7400 series chips, some corroded diodes on the core stack and a power resistor. Hasn't missed a beat since.
Sure. In my years of maintaining gear from that era, I find a lot of dead 7474 and 7440 and some dead 7420 make up 90% of the bad ICs. Every once in a while, a diode.
I don't know if any of you have interest in this sort of thing. I don't have a PDP-8/I but it might not be too difficult to adapt it to one of those or other PDP-8s and maybe 11s.
I think most PDP-8/i are negibus, and the -8/i itself is expecting to implement memory expansion to 8K internally (including using an M702 "memory detector" card in a particular slot). I have a 4K -8/i that I tried to upgrade to 8K when i was still learning (and lacking in the PDF scans we have now) that I was unsuccessful with due to my lack of deep understanding of how all the parts work (G020 -> G021 was one I totally missed as a teenager). It might be easier on an -8/i to remove the original memory parts and just use the Zynq board for all 32K (or do what was somewhat common back then, 8K with DEC parts and "external 24K" which _was_ done with non-DEC expansion boxes). I would definitely love to learn how to get one or two of these. Not as interested in the frontpanel emulators. I can see how they are handy but I'd prefer the original look. Thanks for sharing! -ethan