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Re: New Board Development - SBC6120-RBC Edition [message #5314 is a reply to message #5313] |
Thu, 11 October 2018 15:40   |
tingo
Messages: 114 Registered: February 2017 Location: Oslo, Norway
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FWIW, I found that simply doing 'screen /dev/ttyUSB0 9600' (or whatever your usb serial port is called) works. Of course, this was after I had spent some time trying to get usb-to-ttl adapters working (blush)...
Torfinn
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Re: New Board Development - SBC6120-RBC Edition [message #5325 is a reply to message #5324] |
Sun, 14 October 2018 15:07   |
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Andrew B
Messages: 467 Registered: October 2015 Location: Near Redmond, WA
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So - there have been a few people who have been waiting a long while for 'wait list' stuff. Apologies to the people who have patiently waited. I hate to take any $$ unless I know I can ship promptly, so it's been slow going since I made the giant bath of 65 original kits. I'm ordering some GALs + EEPROMs to get caught up along with more PCBs. I have a few tested 6120s left but based on the wait list I have, I believe that they are all likely spoken for at this point. If I get through the list and any are left, I'll post back here.
The mis-numbered D1-6120 from UTSource seems like a good option right now.
[Updated on: Sun, 14 October 2018 15:07] Report message to a moderator
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Re: New Board Development - SBC6120-RBC Edition [message #5327 is a reply to message #5321] |
Mon, 15 October 2018 09:48   |
scruss
Messages: 62 Registered: December 2015 Location: Toronto, Canada
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Andrew B wrote on Sat, 13 October 2018 15:57Seems like you might still have some kind of a serial problem?
If you boot without the flash card attached, and type 'h <enter>' at the prompt, do you get the monitor ROM help?
Can you dump RAM, 'e 0000-1000 <enter>'
Can't seem to do either. Entering 'H<cr><lf>' at the prompt usually returns a <lf>. This last time I've tried it, all three POST lights lit up and it seems to have hung.
(I'd be happy to start another thread about this, as my serial issues must be tedious for other readers.
What I've tried/tested:
- two different null modem cables
- two different serial adapters
- continuity between 6402 and MAX232: good
- continuity between MAX232 and serial out: good
- capacitors on MAX232 are all good
- Replacing the MAX232 with a socket and USB serial adapter resulted in all three POST bits lit and no useful function
- reset button often doesn't work, even if held for a long time and no CF2IDE adapter present. Usually resets to just power LED and no POST
- both oscillators doing their job (or there would be no coherent monitor message)
- no obvious bent pins or shorts in the dual-wipe sockets
- I have been more careful with ESD precautions with this build than any other, given the dire warnings in the manual
- The board was less compatible with my lead-free + no-clean flux soldering setup than I'd hoped
- (smallest CF I current have is 512 MB, and written using Etcher; I'm getting smallest cards I could find by mail this week)
Guess I'll have to trace every line and see if something's not connected.
> Does anyone know what each of the pins on the 6502 CPU chip in the Apple II Plus does?
They all plug into the socket on the motherboard to keep the chip from drifting away. - c.s.a2 FAQ of yore
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Re: New Board Development - SBC6120-RBC Edition [message #5336 is a reply to message #5327] |
Mon, 15 October 2018 20:02   |
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Andrew B
Messages: 467 Registered: October 2015 Location: Near Redmond, WA
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It sounds like you're getting to the end of all of the logical things to do.
Did you happen to substitute any of the 7400 series logic with a different series compared to what is in the BOM? We had strange intermittent issues with some 74ACT (I think?) chips on the Rev 0.99 board, but I went to thicker power & GND traces + 2 Oz copper on the Rev 1.xx boards and that seemed to resolve that issue, even the previously problematic chips worked fine.
Where did you source the rest of the chips for the build?
I don't mind if we stay in this thread or split it off, totally up to you.
[Updated on: Mon, 15 October 2018 20:03] Report message to a moderator
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Re: New Board Development - SBC6120-RBC Edition [message #7525 is a reply to message #7520] |
Tue, 14 April 2020 16:09   |
scruss
Messages: 62 Registered: December 2015 Location: Toronto, Canada
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Thanks! Caught the problem on the first elimination: the USB-Serial null-modem combo was wired wrongly. Swapping it for the one on my Zeta2 made it happy.
> Does anyone know what each of the pins on the 6502 CPU chip in the Apple II Plus does?
They all plug into the socket on the motherboard to keep the chip from drifting away. - c.s.a2 FAQ of yore
[Updated on: Tue, 14 April 2020 16:17] Report message to a moderator
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Re: New Board Development - SBC6120-RBC Edition [message #7980 is a reply to message #7525] |
Tue, 22 September 2020 14:17   |
kb811
Messages: 3 Registered: September 2020
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Junior Member |
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I have just built two RBC versions of the SBC6120 and am pleased to report that they appear to work fine at both 5 and 8 MHz (for example: booting into OS/8 and running adventure).
The only problem I had eventually turned out to be the Microchip ATF22V10C[QZ] devices and the TL866II Plus programmer I used to program them - the SBC6120 would start up, but there were various random behaviour issues and it wouldn't boot into OS/8. Initially I thought it might be my soldering, a PCB problem or a dodgy processor. But after lots of testing and making up a second one (that behaved exactly the same) I grew suspicious of the ATF22V10C[QZ]s and then found that things were fine using secondhand Latice GAL22V10Bs. Later, after investigating the ATF22V10C[QZ], I found out about the programming instructions described below; those devices also now work fine.
Using ATF22V10C[QZ] devices: "Condition" the device (probably true for any programmer; see below). Select the "UES" profile for the device in the TL866II Plus software when programming them.
References (where I found out about this):
The following link provides useful info about how to correctly program Microchip ATF22V10C[QZ] devices:
http:// forum.6502.org/viewtopic.php?f=10&t=6065&start=30#p7 5562
The conditioning instructions are described near the end of the webpage at the following link, to be used before programming new (and I would assume, "just in case", recently obtained or previously unconditioned) devices:
http://www.bhabbott.net.nz/atfblast.html
[Updated on: Wed, 23 September 2020 13:11] Report message to a moderator
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Re: New Board Development - SBC6120-RBC Edition [message #8024 is a reply to message #454] |
Fri, 16 October 2020 14:40   |
kb811
Messages: 3 Registered: September 2020
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Junior Member |
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IOB6120
I have just completed building an IOB6120. RTC and battery backup are installed. Everything tested so far seems to be working fine! Things I haven't tried yet are the printer port, the on board serial ports or the digital I/O. Unknown: use of VMAx: from OS/8. I probably need to "exercise" it a bit more.
I constructed Vince Slyngstad's revision of the original that he describes here http://so-much-stuff.com/pdp8/sbc6120/iob6120.php.
The original is described here https://www.jkearney.com/sbc6120/iob6120.htm.
Some additional information can be found here https://tinymicros.com/wiki/IOB6120.
NOTE: Checking the schematics is a must when constructing any of these.
OS/8 boots off a compact flash card in the IOB6120's CF socket (you need to map the partitions first).
There is one known problem: "the Fortran run-time system does not work with the IOB6120"; see http://www.sparetimegizmos.com/Hardware/SBC6120_Adventure.htm.
I wonder if this might be a VT52/IOB6120 "TTY" I/O implementation issue (TBC): whilst I was pondering why Adventure did not work and everything else seemed to, I noted that Adventure seems to be fine if you run the system via the serial port on the SBC6120 (whilst still running OS/8 off of the CF plugged in to the IOB6120). I might see if I can figure out the problem sometime.
Assembly
The PCBs I got back from fabrication had an issue with the silk screen (I don't know why). But everything else seemed to check out okay.
The first mistake I made was using solder paste! There are three SMD components with a very fine pitch, so solder paste and heat seemed to be the best way to go. This worked very well for all the other SMD components, but not the fine pitched ones (stencil, syringe and then just-daub-it-on methods tried). Maybe there was a problem with the solder mask, or my technique.
I gave up on the solder paste and started again with a soldering iron (and another fresh PCB). I used a tip just small enough that it would not immediately bridge multiple pins to solder the fine pitch pins one by one by hand (microscope/visual assistance required for this)! This was much easier than anticipated, although somewhat time consuming. Fingers crossed that all pins are actually soldered down (I double checked with the microscope twice). A very small number of bridges between pins did occur, but were easily taken care of with "solder wick" because I was soldering from the "outside". I also hand soldered all the other SMD components whilst I was at it, except for the crystal. I used solder paste and a hot air station for the crystal as that seemed easier/safer for its style of packaging and device type (but soldering it with an iron would probably have been okay).
The second mistake was the use of shrouded headers for the digital I/O headers (io1 and io2); this is currently preventing me from soldering in the CPREQ jumper extension.
Inter-board connection
I used a stacking header. I couldn't find one with the height and pin length that I would have preferred; so I opted to use two Adafruit headers designed for the Raspberry Pi (one 2x20, and 2x5 carefully cut from another; for extra strength glue was applied to the two ends that butt together just prior to them being soldered in to place). It would be better to have greater separation between the boards (longer header pins) without looking for an additional "stacker" to build it up or needing a shield to prevent shorts (things are particularly close with the socketed crystals on the SBC6120). BTW, stacking them the other way would block direct access to the top of the IOB6120.
Whether, or not, a stacking header is really needed depends on decisions about a front panel .
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Re: New Board Development - SBC6120-RBC Edition [message #10768 is a reply to message #10719] |
Thu, 16 May 2024 09:06  |
thunter0512
Messages: 2 Registered: January 2021
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Junior Member |
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The freezing problem was caused by a RCA 6402 UART. Harris and Intersil 6402 UARTs work fine and don't cause this freezing of the FP6120 display. The RCA UART was working fine as a UART, but somehow it caused the freezing when the count rolled over from 7777 to 0000.
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