Yes, pin 26 TERMPWR should not be connected to VCC and left open; great catch. On the other pins stated below based on the NCR documentation;
“On the single-ended signals, all odd numbered lines plus 20, 22, 24, 28, 30 and 34 are connected to ground on the controller and pin 25 is left open”.
Norberto
On 1/10/13 5:02 PM, "Alan Hightower" wrote:
I'm not sure where the last wiki update came from but it points out a problem. Pin 26 should not and cannot be a board power supply. It is termination power only. If you have a long cable with passive networks at both ends, SCSI supply is only guaranteed to provide enough power to handle peak switching loads from the pull ups. There's some margin but not enough to handle the hundreds of mV the emulator board pulls. If someone tries to power their emulator from it, they will eventually burn up the termination reg on their host controller.
Also pin 25 should be left un connected and not to ground. I've seen devices short pin 25 and 26 together. Pins 23, 24, 27, and 28 should also be open.
-Alan
Sent from my iPad
On Jan 10, 2013, at 7:26 PM, "Andrew Lynch" wrote:
Thank you very much Wayne! Your efforts have tremendously moved the S2I project forward! The wiki page is great!
All the recent interest has caused a bit of upsurge in interest in the S2I project in general. So far I have sent out three of the remaining four prototype PCBs. Hopefully this means we can continuing build and test and get some more diverse working systems out there to “shake down” the prototypes.
I really appreciate your leadership on the S2I project. This is going to benefit the wider hobbyist/vintage/classic computer community for many years to come.
Thank you!
Andrew Lynch
From: Wayne Warthen [mailto:wwarthen@gmail.com]
Sent: Thursday, January 10, 2013 1:03 AM
To: Andrew Lynch
Cc: Norberto Collado; Douglas Goodall; mouse@netbsd.org; Charles Phillips; jwsmail@jwsss.com; Alan Hightower; leonb@swiftdsl.com.au; nestor ruiz; Clem Maloney; Geoffrey Reed; Matthew Hudson; Ryan Wallmow; cotsco@frontiernet.net; Miro Svetlik; ..I'd rather be coding ASM!; Bob Devries; Marc Holz; Mark H. James; Mark Martin; RobJ; Bob Grieb
Subject: Re: lost emails on SCSI to IDE/SD converter project
Hi Folks,
I have posted a couple things to the Wiki tonight.
The file http://n8vem-sbc.pbworks.com/w/page/62549548/S2I%20Status is a document describing the status of the S2I Firmware Project. It includes how to build and use the firmware. It needs a lot more work, but should get folks going.
More importantly, the file http://n8vem-sbc.pbworks.com/w/file/62549540/S2I%20Firmware.zip is an archive with the firmware source and full build environment along with the current firmware build.
Everything is still really rough, but the rate of progress on this seems to be increasing. The firmware is definitely now monitoring the SCSI bus and appears to be accurately following bus signals. In theory, I am only a few hours away from adding enough code to prove that a SCSI command/response can be completed. See below for a sample of a test run of the firmware.
Contributions of any kind are welcome!
Thanks,
Wayne
“On the single-ended signals, all odd numbered lines plus 20, 22, 24, 28, 30 and 34 are connected to ground on the controller and pin 25 is left open”.
Norberto
On 1/10/13 5:02 PM, "Alan Hightower" wrote:
I'm not sure where the last wiki update came from but it points out a problem. Pin 26 should not and cannot be a board power supply. It is termination power only. If you have a long cable with passive networks at both ends, SCSI supply is only guaranteed to provide enough power to handle peak switching loads from the pull ups. There's some margin but not enough to handle the hundreds of mV the emulator board pulls. If someone tries to power their emulator from it, they will eventually burn up the termination reg on their host controller.
Also pin 25 should be left un connected and not to ground. I've seen devices short pin 25 and 26 together. Pins 23, 24, 27, and 28 should also be open.
-Alan
Sent from my iPad
On Jan 10, 2013, at 7:26 PM, "Andrew Lynch" wrote:
Thank you very much Wayne! Your efforts have tremendously moved the S2I project forward! The wiki page is great!
All the recent interest has caused a bit of upsurge in interest in the S2I project in general. So far I have sent out three of the remaining four prototype PCBs. Hopefully this means we can continuing build and test and get some more diverse working systems out there to “shake down” the prototypes.
I really appreciate your leadership on the S2I project. This is going to benefit the wider hobbyist/vintage/classic computer community for many years to come.
Thank you!
Andrew Lynch
From: Wayne Warthen [mailto:wwarthen@gmail.com]
Sent: Thursday, January 10, 2013 1:03 AM
To: Andrew Lynch
Cc: Norberto Collado; Douglas Goodall; mouse@netbsd.org; Charles Phillips; jwsmail@jwsss.com; Alan Hightower; leonb@swiftdsl.com.au; nestor ruiz; Clem Maloney; Geoffrey Reed; Matthew Hudson; Ryan Wallmow; cotsco@frontiernet.net; Miro Svetlik; ..I'd rather be coding ASM!; Bob Devries; Marc Holz; Mark H. James; Mark Martin; RobJ; Bob Grieb
Subject: Re: lost emails on SCSI to IDE/SD converter project
Hi Folks,
I have posted a couple things to the Wiki tonight.
The file http://n8vem-sbc.pbworks.com/w/page/62549548/S2I%20Status is a document describing the status of the S2I Firmware Project. It includes how to build and use the firmware. It needs a lot more work, but should get folks going.
More importantly, the file http://n8vem-sbc.pbworks.com/w/file/62549540/S2I%20Firmware.zip is an archive with the firmware source and full build environment along with the current firmware build.
Everything is still really rough, but the rate of progress on this seems to be increasing. The firmware is definitely now monitoring the SCSI bus and appears to be accurately following bus signals. In theory, I am only a few hours away from adding enough code to prove that a SCSI command/response can be completed. See below for a sample of a test run of the firmware.
Contributions of any kind are welcome!
Thanks,
Wayne