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sark02
PostPosted: Mon Jan 04, 2016 2:14 am 
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magetoo wrote:
sark02, I'm not sure you were adressing me specifically
I was :D
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However, keep in mind that within the bounds of this project, I have a soldering iron, the usual parts in a hobbyist electronics lab, and no computer. The conveniences that Flash memory provides, like in-system single-supply-voltage programming, aren't really all that relevant at that point.
FLASH (also EEPROM) are ideas to avoid the UV Erased EPROM - which would have been in use in the 70s/80s. Nothing crimps my flow like having to wait 15 minutes for a UV Eraser to wipe a chip.

As I alluded to before, the computers from the 70s and 80s that we've all heard of were built upon the shoulders of the tech that came before. Minicomputers to edit and assemble programs, transfer those programs over to EPROM burners or transmit them down custom programming paths. There's no glory in writing code on sheets of paper and hand-assembling them. I had to do that in school, for "Introduction to Microprocessors", and for anything beyond 10 or 20 lines it's simply tedious. I would not recommend it.
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GARTHWILSON
PostPosted: Mon Jan 04, 2016 3:22 am 
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sark02 wrote:
FLASH (also EEPROM) are ideas to avoid the UV Erased EPROM - which would have been in use in the 70s/80s. Nothing crimps my flow like having to wait 15 minutes for a UV Eraser to wipe a chip.

When I was developing with UV EPROM (including EPROM-based microcontrollers), I used an eraser that held four at a time, then rotated them, so at 16 minutes total erase time, I'd have another one every four minutes, which was quick enough to see what I did wrong, edit the source code, and run the assembler and programmer again, and try it again. When I first started out though, before I had a computer at all, I had to put the EPROM in the sun for a week.

My first programmer was manual, using DIP switches to set address and data, and a pushbutton to trigger a 50ms programming pulse. As you can imagine, it was slow; but worse, it was very prone to human error. If it were EEPROM, you could correct mistakes without starting over. I found out later that many DIP switches (including the ones I got) are only guaranteed for about 100 cycles. I probably didn't get much further than that before a friend who had made himself a programmer controlled by his calculator offered to help. This was for my first computer.

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There's no glory in writing code on sheets of paper and hand-assembling them. I had to do that in school, for "Introduction to Microprocessors", and for anything beyond 10 or 20 lines it's simply tedious. I would not recommend it.

What I did for that first computer above was to flowchart everything on paper, and put the machine-language instructions in the boxes along with the assembly language. Then I'd transfer the machine language to sheets with 256 rectangles in a 16x16 grid to keep better control of my manual EPROM programming process. I might not have even filled the first page before my friend volunteered to help with his home-made programmer.

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sark02
PostPosted: Mon Jan 04, 2016 4:07 am 
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GARTHWILSON wrote:
What I did for that first computer above was to flowchart everything on paper, and put the machine-language instructions in the boxes along with the assembly language. Then I'd transfer the machine language to sheets with 256 rectangles in a 16x16 grid to keep better control of my manual EPROM programming process.
Oh dear Lord...!
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GARTHWILSON
PostPosted: Mon Jan 04, 2016 4:11 am 
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Oh dear Lord...!

Soon after that I was using the 2500AD assembler and a Bytek Writer programmer.

When I watch the computer history videos, I marvel at the dedication the computer pioneers showed, which far exceeded my own. When you don't have modern tools yet though, you make do and push forward with what you have, however primitive it might be. So many beginners today have no concept of that, and think they need all the modern tools whose insides they have no hope of understanding, so they become appliance operators.

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magetoo
PostPosted: Mon Jan 04, 2016 4:38 am 
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sark02, I think you may have missed the part where this is supposed to be an exercise in starting with nothing. Not using already existing tools is the whole point! (This is also why I wasn't sure who you were adressing your comments to.)

We can take this discussion to PMs if you want to talk further, or if you can wait I'll start a new thread when it gets going.
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sark02
PostPosted: Mon Jan 04, 2016 5:22 am 
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magetoo wrote:
sark02, I think you may have missed the part where this is supposed to be an exercise in starting with nothing. Not using already existing tools is the whole point! (This is also why I wasn't sure who you were adressing your comments to.)
Understood. I have nothing more to add. Take photos and keep us informed on your progress! Cheers!
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BigDumbDinosaur
PostPosted: Mon Jan 04, 2016 7:40 am 
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sark02 wrote:
FLASH (also EEPROM) are ideas to avoid the UV Erased EPROM - which would have been in use in the 70s/80s. Nothing crimps my flow like having to wait 15 minutes for a UV Eraser to wipe a chip.

I continue to use UV-erasable EPROMs because they outperform most other types. I have about 20 of them around here and when I get down to the last few I put the used ones in my eraser. I don't have to wait, because I have erased ones still available.
Attachment:
File comment: Homemade EPROM Eraser
eprom_eraser01.jpg
eprom_eraser01.jpg [ 673.84 KiB | Viewed 2318 times ]

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As I alluded to before, the computers from the 70s and 80s that we've all heard of were built upon the shoulders of the tech that came before. Minicomputers to edit and assemble programs, transfer those programs over to EPROM burners or transmit them down custom programming paths. There's no glory in writing code on sheets of paper and hand-assembling them. I had to do that in school, for "Introduction to Microprocessors", and for anything beyond 10 or 20 lines it's simply tedious. I would not recommend it.

I don't think that anyone at this point in time is suggesting that we regress our development tools 35 or 40 years.

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BigEd
PostPosted: Mon Jan 04, 2016 9:10 am 
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On the subject of photodiodes - you don't need them! An LED can do both jobs. Although in the distant past I did buy a phototransistor which IIRC had a Darlington pair inside.

I like Garth's idea of using photonics for both clock and data - if you include data and address and a strobe then you should be able to get away with no firmware at all, which is just what you want. Or get a little more complex and include a counter or incrementer chip.

You'll only need to load 100 bytes of code, at most, to be able to use that to read code more conveniently over a UART or using a keypad or a PIA.
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banedon
PostPosted: Mon Jan 04, 2016 1:45 pm 
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Happy New Year everyone :).

With regard to the EEPROM side of things: I have a whole bunch + a UV eraser, but I tend to stick with my Winbond 27C512-45Z's EEPROMs as I have a load of these, they run at 45ns (rather than the 70ns-120ns that most EPROMs utilise) and don't need to be UV erased for 15 mins. If anyone sees some fo these going then I'd suggest picking them up.

My list if things to do this year:

Complete my I2C 65xx code library
Create an SPI 65xx code library
Work out how to do VGA. This still puzzles me!
Make 6502GPD v2
Create a 65C812 system.

Lots more of course, but only I have so muhc time :).
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GARTHWILSON
PostPosted: Mon Jan 04, 2016 8:09 pm 
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banedon wrote:
With regard to the EEPROM side of things: I have a whole bunch + a UV eraser, but I tend to stick with my Winbond 27C512-45Z's EEPROMs as I have a load of these, they run at 45ns (rather than the 70ns-120ns that most EPROMs utilise) and don't need to be UV erased for 15 mins. If anyone sees some fo these going then I'd suggest picking them up.

That is fast for PROM. I think the fastest EPROM I've seen is 55ns (I have these), maybe 45ns. Nothing faster. I wonder if there are any of the type of PROMs where you actually blow fuses to program them that would be any faster. Probably not, since those fell out of favor before clock speeds got turned up so high.

Quote:
My list if things to do this year:

Complete my I2C 65xx code library
Create an SPI 65xx code library
[...]

Since you mentioned my I²C code earlier, I also have efficient bit-banging SPI code at http://wilsonminesco.com/6502primer/SPI.ASM, referenced in the 6502 primer's circuit potpourri page under "Interfacing to SPI and Microwire," at http://wilsonminesco.com/6502primer/pot ... ITBANG_SPI . The code there only does one direction at a time simply because although SPI is full duplex, none of the SPI ICs I've used actually used the full duplex. Writing a full-duplex byte transmit/receive routine would not be difficult. Daryl also offers his 65SPI (not to be confused with 65SIB), at https://sbc.rictor.org/65spi2.html [link edited for the updated one, since the CPLD he was originally using became unavailable].

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BigDumbDinosaur
PostPosted: Mon Jan 04, 2016 8:50 pm 
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GARTHWILSON wrote:
banedon wrote:
With regard to the EEPROM side of things: I have a whole bunch + a UV eraser, but I tend to stick with my Winbond 27C512-45Z's EEPROMs as I have a load of these, they run at 45ns (rather than the 70ns-120ns that most EPROMs utilise) and don't need to be UV erased for 15 mins. If anyone sees some fo these going then I'd suggest picking them up.

That is fast for PROM. I think the fastest EPROM I've seen is 55ns (I have these), maybe 45ns. Nothing faster. I wonder if there are any of the type of PROMs where you actually blow fuses to program them that would be any faster. Probably not, since those fell out of favor before clock speeds got turned up so high.

JAMECO at one time still listed PROMs but I seem to recall that they were quite slow. I use AMD's 27C256 EPROMs, which are 55ns and are available from JAMECO. I have tested Atmel's 27C256-45 OTP in POC, which is functional at 15 MHz.

The Winbond 27C512-45Z EEPROM is special order from Digi-Key. Mouser does not list it at all.

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banedon
PostPosted: Tue Jan 05, 2016 12:53 am 
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I got my W27C512-45Z's as a batch lot of 20 on ebay and really cheap. I had no idea at the time that they were such a good deal as I'd only just begun my 6502 sojourn. I noticed that some OTP EPROMs run at about 55ns. Not sure why they are listed as EPROM rther than just PROMs though...
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scotws
PostPosted: Fri Feb 26, 2016 4:12 pm 
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Remember Mario was talking about his Z1013-project in this thread? He's being modest (again), but I'm going to rat him out, because he's written a really cool article about his adventures with the East German computer system: http://www.golem.de/news/ddr-computer-w ... 19183.html In German, of course, but between Google Translate and the great pictures well worth your while. Great work, Mario!
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