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  1. S

    DEC Board Designs = Art

    More specifically related to "art", for many years most boards designed in CXO (Colo. Springs) included the artwork seen in the example below. It was designed by PCB layout engineer Eric Somers, who was still in CXO until a few months ago - Eric is an all-around great guy. I've heard that the...
  2. S

    an ODT for T-11

    Hey Henk! Glad to hear from you again! I should mention: On those PCBs, of course the interrupt is not connected. On mine, the UART IRQ signal is "ECO-wired" to CP3 (pin 33) on the T-11. The interrupt vector will then be at address 114(8). Pete
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    an ODT for T-11

    Yep, did all those experiments in various combinations years ago. Setting those mode bits to match the HW config is required at every power-up. My "sandbox system" has DIP switches to make it real easy to try different things. The fix I described with adding Receive interrupt support is easy...
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    an ODT for T-11

    Just now sent info and code to the email indicated by your forum name. For other's interest, here is a description of the solution: My *belief* is that the UART issue was when the code would test the Receive Ready (or Transmit Ready) bit before sending/receiving a byte. The T-11's bus behavior...
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    Quick Look at PDP-8 and PDP-11 Systems on Chip

    Also the RQDX disk controllers (1, 2, and 3) use a T-11. And there is one inside the VT-240 (along with an 8085, IIRC). Pete
  6. S

    Quick Look at PDP-8 and PDP-11 Systems on Chip

    Also built this. It's a large wire-wrap board, used as a 'sandbox' for experimenting with different T-11 related stuff. Features currently include: - T-11 with 8KB RAM and 8KB EEPROM (in a ZIF socket). - AY3-1015D UART (like used on some old DEC serial boards). - Intel 8255A parallel I/O. - A...
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    Quick Look at PDP-8 and PDP-11 Systems on Chip

    Yes. See this thread: https://forum.vcfed.org/index.php?threads/an-odt-for-t-11.1236982/#post-1243830 Also, a few years ago I built this clock (picture below). The board is wire-wrapped. The time base is a vintage 3.579545 MHz TV colorburst crystal (in a cool glass envelope!), driving an MM5369...
  8. S

    replacement for DEC AC input Y-capacitors, aka common-mode capacitors, aka bathtub capacitors

    I understand that they are "there for a reason" in Enterprise/Industrial applications, but what about just disconnecting them? Is there enough of an EMI issue (etc.) to be concerned about in a Hobbyist application? Pete
  9. S

    Curious - BA23 power supply size - 345W?

    Perhaps it is the difference between worst-case input power (345) vs the PS *output* power? Pete
  10. S

    an ODT for T-11

    >Pete, This is the board a few of us built a while back, right? I can’t recall if it was a kit or just a bare board. I got mine working and it’s in my shop somewhere. Time to dig it out! -Crawford Hi, I made a PCB back in 2015, and re-sold several of them to various folks. Some were "kits" of...
  11. S

    DEC 10A transistor

    One possibility is that "C1048" refers to 2SC1048 (Japanese transistor). The Japanese part markings often omit the "2S" part. Pete
  12. S

    DEC PDT-11/150

    >Was it ever sold without the second floppy drive? I don't believe so. However, there was a PDT-11/130 and 110. The 130 is a VT-100 with an LSI-11 CPU inside, plus a dual TU-58 tape drive. Very much like a VT-103, but without the Qbus backplane inside. The 110 is lacking the TU-58, and has...
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    an ODT for T-11

    I'm apparently still working on this ;-). I added single-step capability - all in software, using Trace-Trap. It's the first time I've done anything with the "T-bit" - it took me hours to get a couple of bugs out. The "+" key does a SST, after breaking out of the code using ESC. Code attached...
  14. S

    Teletype pin-up printouts

    Trivia: When I worked in DEC Storage, I recall that the Diagnostics team implemented a test failure message that included an ASCII-art image of Darth Vader, with the caption "You have failed me for the last time!". Pete
  15. S

    DEC PDT-11/150

    Yes, the PDT will do ODT at the terminal. The chipset is the same as the LSI-11. But NOTE that there's not much upgrade/modification possibility with the HW. There is no backplane; almost everything is on a single large PCB. As I recall, the only "interface" you have easy access to is RS-232. To...
  16. S

    an ODT for T-11

    >Great work Pete! If I ever find enough time, I'd really like to put together a T11 SBC. When I do, this code will surely be on it! Thanks Dave! In case it is useful, attached is the schematic for my board. It does the "8-bit static" mode, which is the simplest mode. I think this is pretty much...
  17. S

    an ODT for T-11

    Updated so that an ESC key or HALT will dump register contents and PSR, and return control to ODT. It captures the machine state in a RAM area, so I suppose I could now allow register editing, then Resume execution, but right now I don't think I'll take it that far. Also various other...
  18. S

    an ODT for T-11

    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...
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    retro video game using T-11

    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...
  20. S

    T-11 experimenting

    The EEPROM burner is working. The HW is mostly just wires. I added a circuit to allow controlling the 5V power via FW, and an LED to show when the power is actually on. It reads an 8KB EE in about 3 seconds. Writing takes about 80-90 seconds. It could go faster, but some EE chips have a...
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