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| Some old school instruments showing how it's done (HP 3325A and Fluke 8506a) |
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| Dave Wise:
--- Quote from: SilverSolder on February 07, 2021, 09:43:29 pm --- --- Quote from: bdunham7 on February 07, 2021, 09:36:12 pm ---It says 'HI 5.0.4' on power up. Is that the firmware version? --- End quote --- Yes, and - the evidence so far - indicates that version number starting with 5 means 8505A, starting with 6 means 8506A. --- End quote --- Skimming the rest of the thread I didn't see anyone revisit this. I just wanted to say, the first thing popped into my head was "Hardware Interface". I wouldn't be surprised if power-up code probed the hardware to determine what model instrument it was running on. FWIW, Dave Wise I did a lot of 8080 assembly-language programming in the early 1980's, working at Tektronix developing firmware for the 4025 and 4027 Graphics Terminals. If you ever displayed a pie chart, you can thank me for the polygon fill code. You wouldn't believe how many corner cases I had to work around to avoid crashing. |
| joeqsmith:
--- Quote from: Dave Wise on December 18, 2022, 02:47:12 am --- --- Quote from: SilverSolder on February 07, 2021, 09:43:29 pm --- --- Quote from: bdunham7 on February 07, 2021, 09:36:12 pm ---It says 'HI 5.0.4' on power up. Is that the firmware version? --- End quote --- Yes, and - the evidence so far - indicates that version number starting with 5 means 8505A, starting with 6 means 8506A. --- End quote --- Skimming the rest of the thread I didn't see anyone revisit this. I just wanted to say, the first thing popped into my head was "Hardware Interface". I wouldn't be surprised if power-up code probed the hardware to determine what model instrument it was running on. --- End quote --- --- Quote --- Online SilverSolder <https://www.eevblog.com/forum/profile/?u=101951> * Super Contributor * *** * Posts: 4210 * Country: 00 * Re: Old school 8080 EPROM disassembly - is it making sense? <https://www.eevblog.com/forum/microcontrollers/old-school-8080-eprom-disassembly-is-it-making-sense/msg3455878/#msg3455878> « *Reply #26 on:* February 09, 2021, 04:15:08 pm » Attached disassembly listing from the Ghidra tool. I still can't get over how comprehensive it is. It knew about the reset jump table without being told, too. We know that the absolutely first thing this instrument does when it starts, is 1) Somehow it figures out which hardware it is running in - this code is used in two different models of the instrument 2) Depending on what hardware was identified, it will display one of the two strings below in the LED display (ignore spaces in front): HI - 5.0.6 HI - 6.0.7 --- End quote --- |
| Dave Wise:
Do you think it stands for Hardware Interface, or just "Hi there"? |
| joeqsmith:
I don't think it matters |
| bdunham7:
The design of the 850xA controllers evolved over the lifecycle of the instrument and I think the size of available EEPROMs went up quite dramatically over that time. I've attached a photo of the EEPROMs from a single-board controller from an 8506A, not a particularly late version. It has both 5.0.3 and 6.0.4, so obviously the EEPROMs have software for both models. Up until 5 minutes ago I would have told you that the hardware determination must be somewhere on the controller itself--IOW the EEPROMs may be shared, but the controllers were not interchangeable between models. I would have thought that because AFAIK the part numbers are different between the models. However, when I plug this controller into a mostly empty 8502A chassis, the display comes up "HI 5.0.3" before it goes to "ERROR". If I plug it into an 8506A with the isolator removed, it comes up "HI 6.0.4" then "ERROR". With the isolator removed it can't see the remaining modules, so it isn't the presence or absence of the Thermal RMS module that is doing it. I didn't try it in my 8505A because it is all buttoned up and calibrated. So there is something on the mainboard in the unguarded bus, not in the controller, that determines this. My 8506A wiring diagrams aren't great and I haven't found where it is. I suppose it could be in the front panel assembly? |
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