I found my problem with the RS-232 circuit.
The culprit is an erroneous symbol provided by the user community in EasyEDA.
I have re-spun the PCB and I am waiting for delivery.

Hi,

I am in the process of building an AIM-65.
Before committing to a complete PCB, I am designing a reduced version AIM-65 Mini.
I intend to use the TTY feature with a MAX232 and to leave out the keyboard and the display till the next revision.
I am still debating using the expensive DL1416 parts ...

Hi,

I recently acquired an Emma II trainer board and the Visa II expansion card.
I found the Emma II user manual online and the MA08 manual with both schematics.
Does anyone know where I can find the Visa II user manual?

Thanks,

The serial connection works ok if I use a Max3232 serial to TTL module which has the Max3232.
That connects to the 4 post header next to the Max232.
For some reason, which I have not figured out yet, the on-board Max 232 circuit does not always work.

Hi,
In response to an information request, I decided to respin my TIM-2.
I have attached the schematic PDF and the tested assembly code.
Note, the schematic indicates Max232 but I have changed this to the Max3232.
Note: for some reason, the decoupling capacitor for the 6116 RAM is missing on the PCB ...

Hi,

This is my first post. As a vintage computer collector I find the eBay listings too expensive.
Instead, I am building my SBC designs.
For this forum, I submit my latest design, the TIM-1.
It differs from the original by replacing the 6530 with a 6532 and EEPROM.
The assembly code had to be ...