38 ms·

Now struggling to resist the urge to upgrade my sad old analog oscilloscope. Thanks, guys! Seriously, though, this is by far the most interesting series of art

Now struggling to resist the urge to upgrade my sad old analog oscilloscope. Thanks, guys! Seriously, though, this is by far the most interesting series of articles I've read in at least 10 years. Digging in and understanding equipment from decades ago, where everything is potentially questionable is a heroic effort. It's like all the good parts of Radio Electronics & Byte magazine combined. A mystery who-done-it for nerds.

gvb 10y ago
Ending in a killer cliffhanger!
- kens 10y ago
  For a bit of a spoiler: we've figured out that the rewiring on the control board converted it to work with a 3K RAM board. But we have a 1K RAM board which has a couple incompatible pins, grounding the signals we need. I don't know why our Alto would have incompatible boards unless some boards were swapped at some point. So we'll probably get a 3K RAM board and hopefully everything will work. If not, we may undo the rewiring.
  - linker3000 10y ago
    3K?? Steady on! My Acorn System 1 does fine with 1.125K Seems a bit reckless to me. PS: The articles have been a great read.
    - kens 10y ago
      Just to make sure everything is clear, the Alto has 256K words of 16-bit main memory. It also has 1K or 3K words of specialized 32-bit microcode memory, which is what I'm discussing above. Since you don't do much in microcode, 3K is a fair bit. (Also note that the microcode memory needs to be much faster (i.e. expensive) than main memory.) So the Alto and Acorn are in totally different worlds as far as memory. (Not to put down the Acorn.)
      - userbinator 10y ago
        Interestingly, microupdates for latest Intel processors are also only a few KB, although they might only be differences from the full microcode.
gh02t 10y ago
Heh, I have a decent DSO, but I'd still love one of those Keysight/Agilent scopes they are using as they have all sorts of useful bells and whistles worthy of electronics nerd lust. They just cost somewhere between $5000 and $10000.

gvb 10y ago

Ending in a killer cliffhanger!

kens 10y ago
For a bit of a spoiler: we've figured out that the rewiring on the control board converted it to work with a 3K RAM board. But we have a 1K RAM board which has a couple incompatible pins, grounding the signals we need. I don't know why our Alto would have incompatible boards unless some boards were swapped at some point. So we'll probably get a 3K RAM board and hopefully everything will work. If not, we may undo the rewiring.
- linker3000 10y ago
  3K?? Steady on! My Acorn System 1 does fine with 1.125K Seems a bit reckless to me. PS: The articles have been a great read.
  - kens 10y ago
    Just to make sure everything is clear, the Alto has 256K words of 16-bit main memory. It also has 1K or 3K words of specialized 32-bit microcode memory, which is what I'm discussing above. Since you don't do much in microcode, 3K is a fair bit. (Also note that the microcode memory needs to be much faster (i.e. expensive) than main memory.) So the Alto and Acorn are in totally different worlds as far as memory. (Not to put down the Acorn.)
    - userbinator 10y ago
      Interestingly, microupdates for latest Intel processors are also only a few KB, although they might only be differences from the full microcode.

gh02t 10y ago

Heh, I have a decent DSO, but I'd still love one of those Keysight/Agilent scopes they are using as they have all sorts of useful bells and whistles worthy of electronics nerd lust. They just cost somewhere between $5000 and $10000.