FYI , there are 2 different 620 schematics 1 on this site and 1 on marks osi board index, both appear to be the same at first glance but in reality are polar opposites
one would be used for 600/610 to 48 pin buss the the other would be for 5xx cpu board to use the 610 for memory and floppy control
they are dated 1 day apart and labeled receiver and transmitter the gates have been flip flopped .
Grant
620 board
620 board
Replica 600 Rev D:8K,CEGMON
Replica 610 Rev B: 24k,MPI B-51 with Custom Data separator D-13
510 on the bench/replica 582 backplane/replica 470a /replica 555/original 570B/2 x Shugart 851
Ongoing : 630 ,620 ,510,542c,custom 590,SA1200,592,594,596,598
Replica 610 Rev B: 24k,MPI B-51 with Custom Data separator D-13
510 on the bench/replica 582 backplane/replica 470a /replica 555/original 570B/2 x Shugart 851
Ongoing : 630 ,620 ,510,542c,custom 590,SA1200,592,594,596,598
Re: 620 board
Very interesting. It looks like two configurations of the same card. The "Receiver" would be the one I was aware of (and the one that was advertised), to allow the SBII to control the 48-line bus.
The "Transmitter" configuration just has all the 7417's plugged in backwards. There are jumpers to invert the R/W control on the 8T26 bidirectional buffers, and to handle asymmetric derivation of the 02-VMA signal, depending on direction. I assume that the +5 and GND rails to the 7417 banks are jumpered as well.
From the naming convention, I would suspect that the designer "identified" with the 48-pin bus, and probably just added in the ability to do the "transmitter" configuration because it was essentially free, and easy to do.
Does anyone have a 620 card? Pictures please?
Dave
The "Transmitter" configuration just has all the 7417's plugged in backwards. There are jumpers to invert the R/W control on the 8T26 bidirectional buffers, and to handle asymmetric derivation of the 02-VMA signal, depending on direction. I assume that the +5 and GND rails to the 7417 banks are jumpered as well.
From the naming convention, I would suspect that the designer "identified" with the 48-pin bus, and probably just added in the ability to do the "transmitter" configuration because it was essentially free, and easy to do.
Does anyone have a 620 card? Pictures please?
Dave
Re: 620 board
Yes the Transmitter board layout does show jumpers to inverse the power on the 7417's it all makes sense now.
Replica 600 Rev D:8K,CEGMON
Replica 610 Rev B: 24k,MPI B-51 with Custom Data separator D-13
510 on the bench/replica 582 backplane/replica 470a /replica 555/original 570B/2 x Shugart 851
Ongoing : 630 ,620 ,510,542c,custom 590,SA1200,592,594,596,598
Replica 610 Rev B: 24k,MPI B-51 with Custom Data separator D-13
510 on the bench/replica 582 backplane/replica 470a /replica 555/original 570B/2 x Shugart 851
Ongoing : 630 ,620 ,510,542c,custom 590,SA1200,592,594,596,598
Re: 620 board
Good eye. In fact, comparing the two layouts, the Transmitter shows the 7417 chips reversed as well. The Receiver has all the chips aligned as expected.
Re: 620 board
No 620 card downunder sorry.
600RevB:16K,2MHz,64x32,470,CEGMON
SuperKit:502,540B,542B,CEGMON, 8" and 5" FDDs
Cards:PE IO,6522 D-A-D, AY3-8910,ProgramGraphics,Color,UK101
WIP:Archive/Restore Util,HexDOS,FDD Emulator
SuperKit:502,540B,542B,CEGMON, 8" and 5" FDDs
Cards:PE IO,6522 D-A-D, AY3-8910,ProgramGraphics,Color,UK101
WIP:Archive/Restore Util,HexDOS,FDD Emulator
Re: 620 board
Picture of the OSI 620 board.
http://www.vintagecomputer.net/osi/600_ ... 0_1978.jpg
(Dave, you might want to grab this photo, as you don't have a photo of the 620 in the archive.)
/Jeff
http://www.vintagecomputer.net/osi/600_ ... 0_1978.jpg
(Dave, you might want to grab this photo, as you don't have a photo of the 620 in the archive.)
/Jeff
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