PDP11HackPlus
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Time flies
It’s been a hectic few weeks, well, month. My mood has been all over the place, and generally trending down. But I have been doing some bits and bobs. I’ve been working on a couple of displays, something retro styled. I wanted to do something like the TIL311 but with a full alphanumeric character set in, so I’ve started on that. It’s slightly shorter than a regular EPROM, but the same 0.6″ wide. When I’m done coding it I’d like to coat it in resin, just to give it that classic TIL311/Retro display kind of vibe. I’ve got a few of these, so it’d be fun to do something with…
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PDP11 Hack+ Bus display
Well I got the PCB and assembled it, and first off when I powered the board up it caused my PSU to go into over current protection. After a little investigation I realised I had grounded the left and right dots, which are not logic inputs like the rest of the chip for some reason, they are the cathodes of the LEDs. So I was basically putting a whole bunch of LEDs between 5V and 0V, oops. So having fixed that, it does indeed light up. The next problem is that I forgot to include the enable line for the memory so that it only displays memory data/addresses rather than…
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PDP/11 Hack+
I’m really pleased to say that over the holiday I managed to get some time and built up my RAM/ROM/Text Display PCB for my DCJ11 system. First power up (just RAM) worked, I could write and read from the memory, YAY! Next up I added the display and that also worked (you can see the block on the right hand most character), however I couldn’t then write to the UART memory address, after a bit of digging I’d got my PAL code wrong for the memory address decoding. I forgot that the DCJ11, despite being a 16 bit chip, can only access 16bits of address. A quick bit of rework…
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Time & motivation
I am still struggling with my mental health, though it is getting better slowly. I’m getting a bit more motivated and I’ve been some work for Isla Instruments, which is a refreshing change. I’ve had an idea for another synth, curse my head, so I’ve jotted it down and put it in the “laterbase”.My current plan is to get the Synth Voice module I designed completed and running (I have PCBs), work on the Isla Instruments project (which will be on going) and do some bits on Epsilon when I get stuck with that and need to free my mind up a little. I’ve put a self imposed ban on…
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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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LTNT (long time no type)
I am trying to keep my blog (this thing) updated regularly, but I’m failing so here are three updates in one! PDP11 Hack Plus I’ll give a quick update on a number of things, firstly with the PDP11 Hack plus board I’ve been doing. Basically I can’t get it jump into the onboard monitor or ODT (Octal Debugging Technique). Whilst I can see a clock and I can see at power up some address and data lines change as if it is looking for a boot strap of some kind, but I cannot get it into the ODT. Mr Usagi Electric has kindly offered to test my DCJ11 chip for…
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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…