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It’s ALIVE!
Well, the new version of the DCJ-11 board worked!!! Here you can see some output from the ODT console (this is me typing “R0/” and it returning the value in octal for that register). you can also inspect the memory, but as it has no RAM yet you get gibberish back. Here is the assembled board; And here is a picture of it all “lit up”, the two buttons are “reset” and “halt”, both with built in LEDs. And finally with it mated to, and powered from, the back plane board It’s currently running with an 8MHz crystal in, and in all honesty for what I’m likely to do with…
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PDP11 Hack plus V2
It’s been a while, life has been difficult of late for a number of reasons which I won’t go into. However I’m slowly getting my electronics Mojo back, so I’ve been working on the PDP11-Hack board With the previous version I think I tried to put too much in too quickly, so I’ve gone back to basics. The new board (V2) has replaced the discrete glue logic with a PLD and I’ve removed the 16bit RAM and address decoding, again, trying to keep it simple and make sure everything works. A PDF can be found here. The PLD code was written by my partner as she’s done a number of…
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PDP11 Hack Plus board, part 2
So my PCBs arrived (I opted for black, just because) and I built one up run tests. Now the 6402 and the DCJ11 are in sockets as they’re hard to find. The two buttons are Reset and Halt, as I couldn’t fit all the LEDs and their driver chips on the board I opted for breakout pins for things I thought I might need to monitor. First problem was a 6402 that was faulty and as a result killed the 1.8432MHz module, somewhat annoying, but in this day and age of chip shortages and fakes sadly not unexpected, so swapping out another 6402 and a new clock module and the…
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PDP11 Hack Plus Board
Well I finally finished the PCB, but I decided to remove the LEDs, all 81 of them. For two reasons, firstly it was turning into a night mare to route, secondly I’m not even sure if this will work. If it does then I will do another board with some extras on, including LEDs. I’ve also made a PDF of the schematic for those interested, when everything is confirmed and working I’ll be sharing the KiCAD files for anyone daft enough to make one 🙂 In the interim here is the PDF of the schematic. Anyway, PCBs have been ordered and should be with me in a week or so,…
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Start of something new & daft
I’ve long had an interest in computers, older computers that is. I mean I grew up in the 80s and that was the era of computers, I had a VIC20, C64 and so on. But what was missing was the blinking lights, which was part of the idea behind the PJ5CPU project (Under the TTL CPU category). Now I also like obscure things and the DEC DCJ11 CPU is one such chip, it is essentially a PDP11 on a chip minus the RAM and peripherals (floppy disk, hard disk, serial, etc), I’ve been after one for a while but didn’t know what I’d do with it, anyway one came up…