On Sun, Jan 8, 2023 at 1:50 PM Chris Zach via cctalk <cctalk(a)classiccmp.org> wrote: I think I've only ever seen pictures. I know I haven't seen one up close. That's just a few common modules, fortunately. Absolutely. Not a lot of benefit having storage without memory extension. FOCAL is absolutely a good starting point for making a 4K PDP-8/L do _something_ interesting. I haven't ever tried doing assembly using the paper tape tools (it's several passes and uses quite a bit of tape) but I have assembled small programs by hand and toggled them directly into the front panel. Obviously that's no fun for anything over a few dozen instructions. -ethan

If all you want is a mass storage, you can do what I did for my NC4000 computer. I took a controller board from an XT and a ST506 drive( only 5 Megs but how am I going to create that much myself. It is better than a floppy controller since it buffers a sector. The computer can run as slow or fast as it wants because you just send it the commands and wait until it tells you that the sector is ready. You can then just read it back, a byte at a time. There is no other special hardware to design, other than possible buffers to handle data size. The XT controller is simple enough to wire up to most any TTL level bus and all the tricky stuff is done for you. My NC4000 was 16 bits and I needed to do byte operations. Since the processor could do short signed constants, I used the high memory address at 0FFFF to do a byte swap, rather than do shifts but shifts would be fine, I just wanted to minimize the number of cycles. I also did a floppy, that same way but the NC4000 was fast enough to read the status of the controller and transfer a byte at a time and keep up with the data rate of a 360 drive. In fact I had to add some delay because it was too fast. I didn't do a DMA for it. Dwight ________________________________ From: Chris Zach via cctalk <cctalk(a)classiccmp.org> Sent: Sunday, January 8, 2023 4:06 PM To: cctalk(a)classiccmp.org <cctalk(a)classiccmp.org> Cc: Chris Zach <cz(a)beaker.crystel.com> Subject: [cctalk] Re: Diablo series 30 or Dec RK03 There is "close" and there is "this thing is going to tip over on me" close. It was pretty impressive: Amazing lights panel that would allow you to see what it was doing, what sector and track you were on, and all sorts of stuff. I wrote a few quick programs to copy the lower 4k of memory to a specific track, it was handy because I could then load up pretty much any diagnostic tape image I wanted in a second. Made a fair bit of noise spinning up, once running you could hear the disks seeking, quite loud. The write protect panel had a square lighted switch for each disk and a sector lockout that I think protected the top sectors of the disk from writing. One 6 foot rack would fit the panel, controller, one drive, and the power supply for the drive then the controller. Pretty hefty, a second drive was in the rack next to it above the pdp8/I and PC08 paper tape reader. It was a truck. I wonder how it's doing these days... C

The nova a 800/1200 series machine and thank you for mentioning about the 8L drives. I’m hesitant to sell or trade it because it does kind of have sentimental value as the first machine I got and especially since it has such a interesting history (nuclear power plant in France). Since those drives for the 8 are so unobtainable I think I’ll just keep it as the basic system with a teletype and also so I’m not having to swap drives between systems every time I want to use it

On Sun, Jan 8, 2023 at 6:40 AM jos via cctalk <cctalk(a)classiccmp.org> wrote: Indeed. I have had a PDP-8/L since I was in High School (eons ago). I have never come up with mass storage for mine and it's long been a goal to be able to do more than paper tape programs on it. Dry so far. Posibus storage devices were, IME, less common than Negibus devices (which would then require a DW08 and by the time you bought all of that, why didn't you get a PDP-8-i in the first place? (especially since you were memory-limited on the -8/L) I do get wanting to max out an 8/L. It was my first and I'd love to get it doing more things, and it's really cool that you can easily see what's happening at the gate level (possible but less convenient with an Omnibus machine), but there's only so much you can do with _any_ 4K PDP-8, and memory expansion boxes for the 8/L may be rarer than Posibus storage devices. It's a lot easier to bring an Omnibus machine up to 32K and there are lots of vintage storage options. Recreating these things with modern components is always a possibility, of course, but I've only ever seen a couple of one-off devices ever come out (like a Posibus DF32D emulator implemented in TTL that happens to need a now-hard-to-find 128Kx16 NVRAM) Personally I'd love to see some Posibus devices get recreated but after this long, I'm totally willing to see if I could get SerialDisk working with an add-on serial port on an -8/L or unexpanded -8/i. My own (perpetual) goal is to run OS/8 on a pre-Omnibus machine. Haven't pulled all the resources together for that yet. -ethan

On 1/8/2023 3:34 AM, jos via cctalk wrote: As others have suggested, a "period correct" 8/L solution with mass storage is difficult. Your best bet is probably a BM08 for the core memory expansion and a TC08 (you'd want Posibus, not the Negibus TC01) to control a DECtape drive. However, a "pure vintage" solution that is willing to mix in later DEC gear opens the door for a DW8E and that should allow for the MMU, more RAM and an RX8E floppy controller. If you're slightly more flexible, there are also modern emulations that either exist or shouldn't be hard to implement to expand the 8/L. (Some of them are on my lengthy "to do" list, since I also have a couple of 8/L.) You'd need memory (and a memory controller) and then could use Serial Disk (or even Console Serial Disk, when that's ready), for example. Vince