• Personal,  Synths

    Better late than never?

    Well, It’s been a while and yeah I’m failing at updating this blog regularly. First an update on synth stuff, I’ve been working on a front panel for my synths, I’m currently fed up with the sound of the analogue synths I’ve heard (though I will say the GS e7 sounds amazing) and I want to build one for myself, this isn’t a product I plan to sell. I’ve designed the voice, using two SSI VCO chips and an NJM2069 VCF/VCA (as I have a few), I’ve got the PCBs for that but haven’t got around to building any yet. The front panel also uses a lot of the same…

  • Delta,  Synths

    Synth stuff

    It’s been a while since I posted anything to do with synths, and that’s largely down to some family issues (my partner not being well, but she’s getting better now) and my mood taking a massive dive. The recent news about Modal hasn’t helped, it’s a huge shame and I do hope that a solution can be found going forward. I thought it was time to give a quick update on my polsynth, currently known as ‘Delta’. I’ve been thinking it through and I think I got carried away which has meant that some of the bugs are now really difficult to find (read I have no idea). So I’m…

  • PDP11HackPlus

    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…

  • PDP11HackPlus

    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…

  • Delta,  PDP11HackPlus,  Personal,  Suzi,  Synths

    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…

  • PDP11HackPlus

    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…

  • PDP11HackPlus

    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,…

  • PDP11HackPlus,  TTL CPU

    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…

  • Delta,  Personal

    Life and Delta

    I’ve succumbed to the dreaded black dog that is depression again, but with the help of my partner, Jayne, I’m getting better. She is very good at looking after me and helping me avoid pitfalls. Jayne is also improving, she nearly ended up having emergency surgery, but has pulled through and we’re waiting to see the consultant early April to find out what can be done to stop this from happening again (this has happened before, and will happen to her again). In the meantime I’ve been taking time to enjoy walking with my dog, Suzi, and appreciate some of the good things in my life, like Jayne, Suzi, my…

  • Delta,  Personal

    Delta & Life

    Recently my partner was rushed to hospital and has spent 5 days in with a serious condition, thankfully she is now out but will need to have major surgery in 6 to 8 weeks. This has got me thinking a lot about my life and what is important to me. She and Suzi are what matter to me above all else, this trip into hospital has really brought that into focus. So what is the upshot? Well, I’m giving serious thought to Delta being my last commercial synth. It takes a lot of work to make a poly synth, and for one person it can be very hard. There’s a…