Products > Test Equipment
Test Equipment Anonymous (TEA) group therapy thread
xrunner:
--- Quote from: Vince on June 29, 2022, 02:34:51 pm ---Exactly.
And floppies are still way cheaper and faster and more convenient to move data around, than HAM radios data links or smoke signals. I will have a floppy any day thanks ! :-DD
--- End quote ---
Vince here's how they will tell you to move data around your lab with a floppy disk -
bd139:
--- Quote from: Vince on June 29, 2022, 02:38:59 pm ---
--- Quote from: bd139 on June 29, 2022, 02:33:06 pm ---USB sticks is where it's at :-DD
As for a Nano, don't think I could sub one in there. PROM has 30ns turnaround. Even a simple C LUT can't touch that I don't think.
--- End quote ---
Yes why bother programming a micro when you can just program a ROM instead and be done with it, anyway ?! :-//
I guess as an exercise for kids why not, but as a practical and efficient solution not really ;D
--- End quote ---
Well it's always a matter of what tools you have available. And 256x4 PROMs are probably more difficult to get hold of than microcontrollers and are more difficult to program.
Consider this which probably does a fairly good job of being a ROM:
--- Code: ---
uint_8 lut[] = {
0x01,
....
0x09
}
void main()
{
// set up ports here
...
// pretend to be a ROM
while (1)
PORTA = lut[PORTB];
}
--- End code ---
Unfortunately each tick is 62.5ns at 16MHz and the LUT is a few instructions worth of indirection and a load-fetch cycle so waaaay too slow.
capt bullshot:
Just use the correct disk - and you've got one thing less to care about
Vince:
--- Quote from: bd139 on June 29, 2022, 02:44:13 pm ---
--- Quote from: Vince on June 29, 2022, 02:38:59 pm ---
--- Quote from: bd139 on June 29, 2022, 02:33:06 pm ---USB sticks is where it's at :-DD
As for a Nano, don't think I could sub one in there. PROM has 30ns turnaround. Even a simple C LUT can't touch that I don't think.
--- End quote ---
Yes why bother programming a micro when you can just program a ROM instead and be done with it, anyway ?! :-//
I guess as an exercise for kids why not, but as a practical and efficient solution not really ;D
--- End quote ---
Well it's always a matter of what tools you have available. And 256x4 PROMs are probably more difficult to get hold of than microcontrollers and are more difficult to program.
Consider this which probably does a fairly good job of being a ROM:
--- Code: ---
uint_8 lut[] = {
0x01,
....
0x09
}
void main()
{
// set up ports here
...
// pretend to be a ROM
while (1)
PORTA = lut[PORTB];
}
--- End code ---
Unfortunately each tick is 62.5ns at 16MHz and the LUT is a few instructions worth of indirection and a load-fetch cycle so waaaay too slow.
--- End quote ---
Yes if you must use a micro because you have it at hand, sure, if it can do it why not.
But if you have to make a board for the micro, and have to buy the micro, then whyt not just put a ROM on that board instead of a micro ?
A ROM replacing a ROM is simpler and makes more sense. 4 bit ROM trouble again not a problem you can use an 8 bit one just as well, and an 8 bit ROM is still way closer to the original 4 bit ROM... then a micro-controller, so more likely to '"just work".
Why try to replace a bicycle with a semi- truck, when you can just a bicycle that might different tyre sizes, but still is a bicycle ! >:D
Regardless of the solution you end up adopting, as long as we get pictures and reports, that's fine with me ! >:D
tggzzz:
--- Quote from: bd139 on June 29, 2022, 01:11:48 pm ---Ok some quick lunch time debuggery today. I have located the 465B failure and for once it's not a tantalum capacitor. Well that's not true, there is one shorted tant but that's not what is killing the 5V rail. It's much much worse!
I eventually chased it around and found out that it only borked the power supply if channel 1 was selected. So I traced that down to the channel switch. And yep, it's a tek ASIC has gone short. But it's not an ASIC! Part is labelled Tektronix 160-0204-00 which is actually a 63S141J fuse programmable 256x4 PROM. Manual confirms this.
Fortunately it's documented!
Now the IC is available for £23 which is a bit much so I am considering what other options I can use here to replace it. The actual original blank PROM is fairly unobtainable and I'd probably fuck it up programming it.
Will mull on it for a few days...
--- End quote ---
What's the clock rate for U1705? Given that A3-7 are probably constant, the limiting speed appears to be the tsu of the Q-PROM-D loop on U1705. If slow enough, then bitbang an arduino class processor.
Failing that:
* PAL/MACH/CPLD
* duplicate the logic in SMD TTL/CMOS on a PCB carrier plugged into the PROM's socket
* EPROM/EEPROM
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