Building an Acorn System 1 replica - 8 x LED Display (05/04/2022)
8 x LED Display.
This output card is probably one of the simplest cards that can be constructed.
The card requires a SAD board to be present in the system, and along with this, you can place the board at any address within the memory map.
This output card is probably one of the simplest cards that can be constructed.
The card requires a SAD board to be present in the system, and along with this, you can place the board at any address within the memory map.
The above image shows the prototype of the card connected to my Acorn development system using the card extender which allows me to poke around on the cards underside with a scope.
The card contains an octal latch buffer meaning that when the cards assigned address is written too, the value on the data bus is latched into the octal latch keeping the relevant LEDs illuminated. The cards address is specified by selecting the appropriate MAP signal, and then 1 of 16 addresses within the segment to use.
Since each card only needs one memory address, you can have up to 16 of these cards within a segment.
The cards are really useful for sending debugging information too, and of course, you don't have to use red LEDs.
There's a video of the original proto-board development version running here.
The plans can be downloaded from the Plans page.
The card contains an octal latch buffer meaning that when the cards assigned address is written too, the value on the data bus is latched into the octal latch keeping the relevant LEDs illuminated. The cards address is specified by selecting the appropriate MAP signal, and then 1 of 16 addresses within the segment to use.
Since each card only needs one memory address, you can have up to 16 of these cards within a segment.
The cards are really useful for sending debugging information too, and of course, you don't have to use red LEDs.
There's a video of the original proto-board development version running here.
The plans can be downloaded from the Plans page.