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I'm checking out this H7225 "constant voltage conditioner" which belongs to the museum I volunteer at. Does anyone have experience with it? What type of installations would typically use one of these? It works fine, although it makes a fairly obnoxious buzzing sound - is that typical for these...

This is related to the recent thread where somebody was asking about making a PDP11 by using a 2901 bit-slice architecture. The KDA50 is one of several DEC modules that already implements a complete 2901 processor. Since I apparently have too much free time ( :-) ), I wrote code for my...

Not sure if this is "useful", but I implemented an ODT subset to run on a T-11 with RAM, EEPROM, and an MC68B50 UART. It does the CR, LF, / and G functions of ODT. At the moment it doesn't support Register access (just memory addresses), since the code has to use registers itself. Code listing...

My daughter works in the hand-held gaming industry, so that inspired me to make a simple "video game" using only 1980's technology. Key features: - The MPU is a DEC T-11, running at 4 MHz. It has 8K of EEPROM, 8K of RAM, an MC68B50 UART, and a few GPIOs. I made the PCB a few years ago, for...

Some of you may recall that 5 years ago I made a PCB for a minimal T-11 system in "8-bit static" mode. This thread discussed it: http://www.vcfed.org/forum/showthread.php?47569-T11-clock-running-Forth&p=369704#post369704 And you may recall that there was an 'issue' related to the MC6850 UART...

In the past, I've hand-built a couple of boards using a T-11 with local RAM, EEPROM, and basic I/O. Now I'm thinking about doing the same thing with an F-11 chip. Has anyone done this before? Is it feasible to get the basic stuff down to just a handful of support chips? Is there enough published...

Oh Knowledgeable Ones, What is this test device called? As I recall, the clear plastic bezel could be replaced for working on other types of CPUs. I gather that this one for an 11/10. Thanks! Pete

Hi, some years ago I asked this question on a forum (maybe not this one?), and may have gotten an answer, but I don't remember. What is this 4-slot hex backplane? Markings: "6101269-1 Rev. G S/N 17079" The metal frame is marked "03239G1". You can see that it is hand wire-wrapped. On each row...

What is a "PCO"? Thanks, Pete

[I hope this type of post is OK. I read the Forum Rules, and it doesn't discuss For Sale postings. I see that there is a Marketplace forum, but it is generalized for all VCF forums. If this is NOT OK, I will ask a moderator to delete it.] This month I am starting my RFP (Retirement Funding...

I'm trying to test a KDJ11-A (M8192) in my little LSI-11 setup, which is a 4-slot dual-height BP. The J11 responds to ODT, and I can poke a simple routine into it, but when I try to run it, it goes off in the weeds. The SRUN signal goes false, and it does NOT return to ODT unless I do a Halt...

My desktop LSI-11 setup. A 4-slot dual backplane with an 11/03 front panel, plus MXV11 and a W9512 wire-wrap module giving some parallel I/O and a pair of D/A's. The fans are 12V, but running from 5V, so they are nice and quiet. The little MCU board hanging on the left side drives the LSI...

I have the following old docs. I would like to give them to a "good home" in exchange for someone scanning them and posting somewhere for everybody. You don't have to take them all - just take whichever docs you are willing to scan and post. In a DEC Inter-Departmental yellow envelope...

Just finished wiring up the parts from a DCK11 "ChipKit". It's a collection of parts to make a custom Qbus interface. Includes a W9512, DC005 xcvr X 5, DC004 Protocol, and DC003 Interrupt. I didn't have an DC003 in my stash, so I harvested one from a broken MXV11. It works! Responds on the bus...

I suppose this type of question has been asked a lot, but Google is not helping me... I'm looking for a simple, basic, PDP-11 disassembler that runs under Windows. In a CMD window would be fine. I found "PDP11GUI", but it has lots of baggage that I don't want, plus it seems to want a...

What is the purpose of the MSPARE (Maintenance Spare) pins on the Q-bus? Pins AK1 and AL1 are connected together on the backplane, as are BK1-BL1, CK1-CL1, and DK1-DL1. Bus Handbook says they are connected on BP, and not bussed, but doesn't hint at what they are really for. Only reason I can...

Question about program initialization on a PDP-11 (specifically LSI-11): If the hardware has the Line Time Clock turned on, which drives a BEVNT interrupt, how is the system inited on power-up? That is, the LTC is going to fire BEVNT interrupts at a 60 Hz rate on power-up. But as the CPU tries...

In the picture, what is the switch panel on the left from? The one on the right is the common type, found in 11/23 cabs and such. The left one is the same physical setup - lights and switches are in the same places, and the mounting holes are the same. But it has two 16-pin DIP sockets for the...

I haven't touched my DEC stuff in a couple of years, but now getting back to it again. In the picture below: LSI-11, 32KW RAM, DLV11-J. The backplane is from a VT-103. The power supply is from a Rainbow. The console goes to a simple level converter (from Sparkfun), which then goes to a T.I...

Hi All, There is another thread discussing the "T11 board" that I designed. A total of 10 boards were fabbed. Fellow forum-reader Mitch has prompted me to consider getting another batch of PCBs. They would be the "V1.1" boards, which fix a couple of minor errata. The main difference is that V1.1...