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Introducing (and interest check) CircuitTalk: LocalTalk for PowerMac G4

CircuitBored

Well-known member
although, wouldn't a G3 circuitTalk work on a G4 Yikes?

Yes, it will! To have been more precise I should have said "G3/PCI G4 version". I believe it will also work in the iMac G3. Theoretically, any computer with the same modem card as the B&W G3 will be compatible.
 

macuserman

Well-known member
Yes, it will! To have been more precise I should have said "G3/PCI G4 version". I believe it will also work in the iMac G3. Theoretically, any computer with the same modem card as the B&W G3 will be compatible.
Put me on the list boss! I've been wanting one of these for ages. I can't wait to get my hands on one of these. If it was orange I'd do a backflip if I was capable. :p
 

rufo

New member
I know I'm late to the party, but as I'm finally starting to dip my toe into my collection of old Macs - if one of these should become available for a Quicksilver G4 (in particular) or an iMac G4, I'd definitely be interested! I had an original Griffin gPort in my old B&W G3, before I sold it to acquire said Quicksilver - so it'd only be appropriate to put one back in 😀 I do see that they're all spoken for in the near term and am in no particular rush, just registering interest in case one should get freed up. (An unsoldered kit or PCB w/BOM would be completely fine with me as well, as the PCBs don't look like they have anything _too_ nutty to solder on them...)
 

opualuan

Member
a second vote for kits, I prefer them. I’ve enjoyed putting together bluescsi and similar- if you have a stack of pcbs and bag o’parts I’m in.
 

joevt

New member
I had an original Griffin gPort in my old B&W G3, before I sold it to acquire said Quicksilver - so it'd only be appropriate to put one back in 😀
I have a Griffin gPort in my B&W G3. I use it for Open Firmware stuff since the B&W G3 doesn't support Telnet in Open Firmware. Currently working on putting newer GPUs up to 512MB VRAM into older Power Macs (as old as Open Firmware 1.0.5). Question: How powerful of a graphics card will work in a beige Power Macintosh G3?

I think I remember the B&W G3 uses a 22.575 MHz PCLK where a baud rate generator constant of 3 would allow 2.258 Mb/s (for synchronous modes) but that's sometimes too fast and fails. A constant of 5 allows 1.613 Mb/s. Some Macs have 15.667MHz PCLK. I think the normal RTxC clock was ≈3.672MHz. Asynchronous modes must divide the clock by 16 or 32 or 64 for the digital phase locked loop. You could bypass the baud rate generator to use the RTxC clock directly (for 115.2 Kbps with X32 clock and 230.4 Kbps with X16 clock asynchronous modes; 3.672 Mb/s is too fast for synchronous modes). Open Firmware can do 115.2 Kbps or 230.4 Kbps with a nvramrc patch, otherwise it's limited to 57.6Kbps. The HSKi or GPi pin can be used as an external clock source. It's been a long time since I played with the serial ports - I used externally clocked synchronous modes to do PlayStation Multitap controller and memory card reads and writes at ≈1 Mb/s (using a 555 timer for the clock). The circuit had a bunch of logic (D flip flops and such). You can't do this stuff with other types of serial ports. Nowadays, one would probably use a microcontroller and do the communication using USB.


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opualuan

Member
I’ve resorted to using a Keyspan pci port adapter, but some apps seem confused by the extra ports. Very interested in this solution.
 
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