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PC6502 + Transputer
So, yeah, I have a thing for transputers, don’t ask me why, I don’t know. I’ve always been fascinated…. Anyway, I finally managed to get some reliable and repeatable comms between my 6502 tower and a T425 TRAM. Here you can see the data going out, and coming back in! In this case writing 0xEFBEADDE to address 0x80000000 (T425 internal RAM). Now this was supposed to be 0xDEADBEEF, but of course, the transputer is little endian.Anyway, output from BASIC program is below; I’ve tried this with the 4 TRAMs (Transputer Modules) I have and they all work!.Here is the tower with the link adapter and a single TRAM on top.…
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PC6502 update
I have been tinkering with various bits of the PC6502 computer system in between looking after Suzi (who is getting better slowly, but we still have a couple of months of hard work ahead of us). Previously I was able to show the OPL3 Sound and Speech card working, Here is an updated video of it playing a tune 🙂 Next I managed to get the display working, this is a 480×272 screen, it has built in fonts and a bunch of features line circle, line drawing and filling, so I can do a bunch of cool things as I go forward with it. I’ve not figured out how to…
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PC6502 Progress
In my previous blog entry I posted about the 6502 computer PCB I made, since then a lot of progress has been made. A lot. Firstly the timing issue has been overcome, the 6502 will now happily run at 14MHz (tested up to 17MHz), the issue was that the way I had implemented the logic in the CPLD for the FT245 serial port was messed up. My partner, Jayne, helped with that and found the issue. I’ve also added a whole bunch of different PCBs, so here’s a couple of pictures; So bottom to top; Aside from the Apple II slot everything is working a treat. Here is a demo…
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It’s been a month, or two
It’s been a while since I wrote, a lot has been going on. Firstly, the Transputer saga, I got a PCB from Oscar Toledo (https://github.com/nanochess/transputer) and confirmed that my TRAMs did indeed pass the tests with his card. However they did not with mine. Then I discovered that somehow none of my TRAMs worked with Oscar’s or my card. Very disheartening. So I’ve paused that for a while, there’s only so much failure you can take before you have to stop something for a bit. In the world of synths it seems things are slowing down globally, in part due to an orange womble in the USA. I have to…
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What’s been happening?
Well I failed at posting once a month, my bad. A lot has been going on since March. I’ve been talking to the new owners of Modal Electronics on and off, since September, and I just stepped away from it. My reasons? There are a few, but mostly because their vision and what I am passionate about in synths are very different things. There were a number of other factors involved, but I won’t go into them. I’ve also not been well, for the couple of weeks I’ve been having major chest pains that come and go, a few days ago I ended up in an ambulance on my way…
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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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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…