------------------------------------------------ | "Behold the eternal glory of Jetfire." | | "I've got no time to talk, I'm on a mission !" | | "What planet am I on ?" | | "My boosters are fried... !" | | "You were duly informed !" | | "I'm too old for this crap." | ------------------------------------------------
WARNING:
The designs here have issues\bugs,
and are only on this page for the C74 project
as a reference what things to do different.
Trying to rebuild any of that stuff in here
most certainly will bring you into trouble,
again: thou shalt not rebuild it.
The plan was to build production quality peripherals and maybe to build transistorized peripherals later...
what went cut back to only building production quality peripherals...
what went cut back to just building experimental peripherals with some neat documentation...
(this was supposed to take one year),
what went cut back to just getting that stuff off my desk after three years and a half,
no matter what...
...as my workflow was disrupted just a few times too many.
As a result, the designs have issues, the documentation has plenty of potholes,
and the schematics should not be trusted too much.
The things in here are only a starting point for those who dare
building 65xx peripherals from 74xx TTL chips.
Nothing more, nothing less.
Be aware, that it might take some years of hard work
to turn those schematics and PCB layouts into something useful,
that you are on your own when making a try,
and that you enter in here at your own risk.
Maybe I better should have used an uni_directional bus structure in those peripherals,
because this would have improved speed and simplified timing.
Peripherals:
X21 < 6521, maybe some minor issues.
X22 < 6522, maybe some minor issues.
X23 < 6523, but no 6523 bus interface.
X32 < 6532, maybe some minor issues.
X45 < 6545, most certainly some issues.
X50 < 6850, failed.
X51 < 6551, failed.
Some PCBs that failed, quite a few of them due to "workflow disruption":
Now for something funny:
Right: 1980, my first hobby computing project.
The Elektor Junior Computer.
Left: 2015, this is supposed to be my last hobby computing project.
X32, experimental 6532 built with 74xx TTL chips.
(only 32 Bytes of 74HCT574 "RAM" installed.)
The 6532 chip is pulled out of the socked in the Junior Computer,
and X32 controlls the display and the keyboard.
Woot !
When I was a 13 years old kid, toying with the 6502,
I was aware that them chips are just made from logic gates and flipflops.
And that "the magic" is just how those elements are connected together
to form a computer.
35 years later, I still have no clue about how those gates and flipflops
are connected together in the original chips...
But in theory, we now could imagine how to connect logic gates and flipflops
together for "rolling our own stuff".
And after spending too many years in a workshop toying with ill fated projects,
maybe it's about time to try some non_technical hobbies.
Now...
Get off my lawn !
[07/2016 Edit: to support the C74 project, some untested\experimental schematics ] [for 6521, 6522, 6532 with internal uni_directional data bus, and that's it. ]
(c) Dieter Mueller 2015