We had a SWTPC system in high school running their unix with the SWTPC terminals. Actually there were 2 systems, each system had 10 terminals attached to it giving the class 20 terminals. That was in 1982. I think those systems had a 6809 and that is where I learned C. My close friend used to go to SWTP and worked with the software guys doing odd jobs and I would tag along with him and check stuff out. Those were the days.
hey up robin! been checking out your vids! nice great to find corsham technologies! just got hold of some for a 6809 i got hold of recently, finally got the disk drives reading flex tonight so onto the next step! i dont suppose if at all you would sell one of your spare music board PCB's?? im not super up on eagle being a kicad fellow myself! i just figured i would ask! ultimately im going to put my own sound card together but would love to give this one a go!! if not no worries ill get off my ass and figure out how to export the pcb files off of eagle ha. thanks a lot. sam
KiCAD 5 has an Import Eagle Project menu item. I (mostly successfully) imported the Corsham Newtech replica board from GitHub. Haven't verified everything yet; It complained about duplicated U4 designator, IIRC, and seemed to lose most of the component part numbers in the schematic, although they display when you try to select them (and it gets confused whether you want the component or some kind of frame - which in turn confuses me :-/ ).
That's really cool! It would be a good idea to add an anti-imaging filter to the output to take some of that nastiness out of the top end. A passive 4-pole filter at 4KHz would do the job.
I’m in the middle of whipping up a 4 channel (or 8, if you double up a pair of PCBs and configure the jumpers right) 8-bit analog output card for sending control voltage to a modular synth rack. I’m building it as a SS30 card; but I’m going to have a cartridge port adapter for my TRS-80 CoCo (I don’t currently have a SWTPC).
Is it feasible to use interrupts instead of adding hot loops for delays? A quick google shows the chip supports IRQ and NMI interrupts but I guess you'd need to be able to ensure they are triggered on a timer like video interrupts are in many other popular 80s micros.
There is an extra interrupt controller card for the SWTPC 6800 which I do have so I think using interrupts to control playback would be possible by the interrupt periods are not very granular. I think it’s possible. deramp.com/downloads/swtpc/hardware/MP_T%20Timer%20Interface/MP_T_AssemblyInstructions.pdf
How much should I expect to get out of my 6800? Altair's go for about $6k currently, obviously doesn't have the same collector base, but it is more rare than an Altair..
I think rarity counts for a lot but it is really set by what someone is prepared to pay. I have seen these on eBay for more than $2k. So I’d suggest that’s around the right starting price for an auction. They come up rarely, because they are so rare. But keep your system together don’t part it out as it’s worth more to a collector as a whole working unit.
@@robingrosset6941 Thanks, that's a reasonable esitmate. I'll probably just keep it around though, no reason to sell a rarity. I definitely wouldn't part it out.
I was wondering that too. One explanation someone suggested is the original board was a single sided PCB and they wanted to avoid extra vias and bridging connections. It’s possible but I would have put in 2 or 3 bridges if it was me.
I was wondering about if it has something to do with 8 bit signed values. Samples on the Amiga used that and 0-127 was from the middle and up, and 128 to 255 was from the bottom up to the middle. Or the other way around... So the bits of the first and second half of the byte are mirrored to each other
@@madmodders normally in a signed byte only 1 bit, usually the most significant is used to represent the sign. So I am not sure it would cut the value in the middle like this.
I have one of the original cards, and the order is actually different than that of the reproduction. Pins 2 and 7 coming out of the 74174 (D5 and D7) are swapped. So if I'm not mistaken that puts everything in the proper order. Mine is a Model 68 Rev B.
Yep. ran your code with data bits 5 and 7 swapped, and everything comes out perfect on my board. I haven't actually found any of the original software yet, I just bought this one.
We had a SWTPC system in high school running their unix with the SWTPC terminals. Actually there were 2 systems, each system had 10 terminals attached to it giving the class 20 terminals. That was in 1982. I think those systems had a 6809 and that is where I learned C. My close friend used to go to SWTP and worked with the software guys doing odd jobs and I would tag along with him and check stuff out. Those were the days.
hey up robin! been checking out your vids! nice great to find corsham technologies! just got hold of some for a 6809 i got hold of recently, finally got the disk drives reading flex tonight so onto the next step! i dont suppose if at all you would sell one of your spare music board PCB's?? im not super up on eagle being a kicad fellow myself! i just figured i would ask! ultimately im going to put my own sound card together but would love to give this one a go!! if not no worries ill get off my ass and figure out how to export the pcb files off of eagle ha. thanks a lot. sam
KiCAD 5 has an Import Eagle Project menu item. I (mostly successfully) imported the Corsham Newtech replica board from GitHub. Haven't verified everything yet; It complained about duplicated U4 designator, IIRC, and seemed to lose most of the component part numbers in the schematic, although they display when you try to select them (and it gets confused whether you want the component or some kind of frame - which in turn confuses me :-/ ).
That's really cool! It would be a good idea to add an anti-imaging filter to the output to take some of that nastiness out of the top end. A passive 4-pole filter at 4KHz would do the job.
Cool! Well done!
Nice vid. Must be similar ages because I thought it was going to say “Greetings professor Falken”
Brilliant!
Nice video! Thanks for sharing a bit of your workflow as well.
Glad you enjoyed it! Thanks!
I’m in the middle of whipping up a 4 channel (or 8, if you double up a pair of PCBs and configure the jumpers right) 8-bit analog output card for sending control voltage to a modular synth rack. I’m building it as a SS30 card; but I’m going to have a cartridge port adapter for my TRS-80 CoCo (I don’t currently have a SWTPC).
Joshua!
"War Games" is a great movie...
Amazing! 👍
Is it feasible to use interrupts instead of adding hot loops for delays? A quick google shows the chip supports IRQ and NMI interrupts but I guess you'd need to be able to ensure they are triggered on a timer like video interrupts are in many other popular 80s micros.
There is an extra interrupt controller card for the SWTPC 6800 which I do have so I think using interrupts to control playback would be possible by the interrupt periods are not very granular. I think it’s possible. deramp.com/downloads/swtpc/hardware/MP_T%20Timer%20Interface/MP_T_AssemblyInstructions.pdf
well done
Thanks!
How much should I expect to get out of my 6800? Altair's go for about $6k currently, obviously doesn't have the same collector base, but it is more rare than an Altair..
I think rarity counts for a lot but it is really set by what someone is prepared to pay. I have seen these on eBay for more than $2k. So I’d suggest that’s around the right starting price for an auction. They come up rarely, because they are so rare. But keep your system together don’t part it out as it’s worth more to a collector as a whole working unit.
@@robingrosset6941 Thanks, that's a reasonable esitmate. I'll probably just keep it around though, no reason to sell a rarity. I definitely wouldn't part it out.
Code from the video is available here github.com/robin7g/swtpc-sound-card
*Look mum no computer brought me here.*
Why in the world did the designer of the card not put the bits in order?
I was wondering that too. One explanation someone suggested is the original board was a single sided PCB and they wanted to avoid extra vias and bridging connections. It’s possible but I would have put in 2 or 3 bridges if it was me.
I was wondering about if it has something to do with 8 bit signed values. Samples on the Amiga used that and 0-127 was from the middle and up, and 128 to 255 was from the bottom up to the middle. Or the other way around... So the bits of the first and second half of the byte are mirrored to each other
@@madmodders normally in a signed byte only 1 bit, usually the most significant is used to represent the sign. So I am not sure it would cut the value in the middle like this.
I have one of the original cards, and the order is actually different than that of the reproduction. Pins 2 and 7 coming out of the 74174 (D5 and D7) are swapped. So if I'm not mistaken that puts everything in the proper order. Mine is a Model 68 Rev B.
Yep. ran your code with data bits 5 and 7 swapped, and everything comes out perfect on my board. I haven't actually found any of the original software yet, I just bought this one.