The extra transformer was sometimes added to the SWTPC. As a boost transformer to increase the voltage to the 5 and 12 volt regulators. The original 7-8 volt to the 5 volt regulator. And 14 volts to the 12 volt regulators was marginal at best. Any drop in line voltage would cause regulation problems. to the DC supplies. Especially if the system had a full 32 k of memory. I made this modification to my SWTPC back in the 70,s shortly after I bought it. I also added a muffin fan to blow air across the memory boards. You might consider adding additional or larger filter capacitors. They help with power supply ripple that is rough on the ram chips. I still have my original system and it still functions. Enjoyed your video .
Actually, the second transformer mod was relatively common. I have two machines with it. The problem was (as you added more cards that used the +/-12vdc the OEM transformer was not up to the task. So you disconnected the +/- 12 vac windings of the OEM transformer & added a "beefier" +/- 12vdc transformer. OR a +/-15vac transformer so that voltage regulator chips on your accessory boards could step it down to the necessary voltage. The later model SWTPc machines had +/- 15volt windings and used 3 terminal regulators on the boards to get the requsite voltage. Incidentally, when adding the second transformer usually the +/-12v rectifiers & caps were replaced with beefier ones.
I'm a retro enthusiast currently building a SWTPC 6800 reproduction, the hardware is working and I can switch between MIKBUG and SWTBUG running at 9600 in an 8k EEPROM, theres 40k of RAM and right now I'm sorting out the cabinet and graphics. I'm representing the CT-1024 using a homebrew terminal based on Geoff Grahams PIC code. I've tried several SWTPC and TSC BASIC interpreters and finally found one that works - had to do some patching to suit this particular hardware. The next job will be to port Star Trek. I'll be posting a vid when its done! There are a few retro projects on my channel :-) Cheers Phil
Very nice work and troubleshooting. I never had one of these kits bitd but always wanted one to play with for the low level side of things. Pretty cool machine.
I don't have a disk controller but I might try to find one and figure out how to get FLEX going along the way. The ROM in this machine is original MIKBUG and not SWTBUG so I think there are a few steps to making FLEX work.
I'm not seeing the data errors on the 300 baud connection? If you're referring to the characters down the right hand side those are the ASCII equivalent characters for the bytes displayed on that row.
The socket pins used are typically used with PCBs that don't have plated through holes thus you need to solder them on both sides of the board. I don't know if the SWTPC PCBs have plated through holes or not.
Ah, old computers! Back then a computer needed half an hour to calculate the first prime number. Those were the days. a computer programmer was treated as a semi god. Things started to go wrong when computers multiplied as rats and the public got hold of it.
Congrats! I built many SWTP kits but Altair 8800 was my first computer. Amazed this thing was in such good condition.
The extra transformer was sometimes added to the SWTPC. As a boost transformer to increase the voltage to the 5 and 12 volt regulators. The original 7-8 volt to the 5 volt regulator. And 14 volts to the 12 volt regulators was marginal at best. Any drop in line voltage would cause regulation problems. to the DC supplies. Especially if the system had a full 32 k of memory. I made this modification to my SWTPC back in the 70,s shortly after I bought it. I also added a muffin fan to blow air across the memory boards. You might consider adding additional or larger filter capacitors. They help with power supply ripple that is rough on the ram chips. I still have my original system and it still functions. Enjoyed your video .
Actually, the second transformer mod was relatively common. I have two machines with it. The problem was (as you added more cards that used the +/-12vdc the OEM transformer was not up to the task. So you disconnected the +/- 12 vac windings of the OEM transformer & added a "beefier" +/- 12vdc transformer. OR a +/-15vac transformer so that voltage regulator chips on your accessory boards could step it down to the necessary voltage. The later model SWTPc machines had +/- 15volt windings and used 3 terminal regulators on the boards to get the requsite voltage. Incidentally, when adding the second transformer usually the +/-12v rectifiers & caps were replaced with beefier ones.
Those buttons on the front panel and the whole design looks so solid and built to last, great video.
I'm a retro enthusiast currently building a SWTPC 6800 reproduction, the hardware is working and I can switch between MIKBUG and SWTBUG running at 9600 in an 8k EEPROM, theres 40k of RAM and right now I'm sorting out the cabinet and graphics. I'm representing the CT-1024 using a homebrew terminal based on Geoff Grahams PIC code. I've tried several SWTPC and TSC BASIC interpreters and finally found one that works - had to do some patching to suit this particular hardware. The next job will be to port Star Trek. I'll be posting a vid when its done! There are a few retro projects on my channel :-)
Cheers
Phil
Wow, thats awesome. Please post the video, I look forward to it!
Long, long, LONG time since I've seen a 300 baud connection. Good find!
it is very slow. I can type faster than it can process!
Good find!
Thanks!
Very nice work and troubleshooting. I never had one of these kits bitd but always wanted one to play with for the low level side of things. Pretty cool machine.
For sure, its great to see these old machines working again.
What a find! Can’t wait to se you get it all going and maybe get FLEX running on it.
I don't have a disk controller but I might try to find one and figure out how to get FLEX going along the way. The ROM in this machine is original MIKBUG and not SWTBUG so I think there are a few steps to making FLEX work.
@@robingrosset6941 For Flex the first thing is you need more RAM at $A000 than the default 128 bytes!
@@robingrosset6941 I have a spare floppy controller for that machine.
I'm not seeing the data errors on the 300 baud connection? If you're referring to the characters down the right hand side those are the ASCII equivalent characters for the bytes displayed on that row.
The socket pins used are typically used with PCBs that don't have plated through holes thus you need to solder them on both sides of the board. I don't know if the SWTPC PCBs have plated through holes or not.
ALL SWTPc boards had plated thru holes.
i remember these
Wow! $100!!
Ah, old computers! Back then a computer needed half an hour to calculate the first prime number. Those were the days. a computer programmer was treated as a semi god. Things started to go wrong when computers multiplied as rats and the public got hold of it.
Aaahhh ummmm and ummmm aaaahh also aaaaahhh