• Board tester, part 1

    sxpert • 01/15/2023 at 10:59 • 0 comments

    Started designing an automated board tester.

    I don't know what computer I should use, a Raspi Pico should be sufficient, but a full raspi could be better, dunno.


    the video is here

  • Started populating the DAP board

    sxpert • 01/15/2023 at 10:56 • 0 comments

    There, I started to populate the DAP board, unfortunately, I am missing the 50-ish 16 legged sockets, so those will have to wait.


    see the video here

  • Just received the first boards

    sxpert • 12/23/2022 at 15:04 • 0 comments

    Finally found some time (and money) to order the DAP boards from JLCPCB.


    here they are in their purple glory (each part of the CPU will have a different color)

    I started to assemble them but I messed up the reference of 2 resistor values in my digikey order, so I'll have to do another order for those...

  • started on the chip tester

    sxpert • 07/10/2022 at 19:53 • 0 comments

    Took some time today to install all the small components -- Resistors and Diodes -- on the chip tester pcb

    will do the rest another day, i't getting too hot , have to turn off the light and soldering iron

  • Received the Retro Chip Tester Pro

    sxpert • 04/13/2022 at 09:04 • 0 comments

    In order to make sure everything works, I have ordered a Retro Chip Tester Pro from Stephan

    https://8bit-museum.de/sonstiges/hardware-projekte/hardware-projekte-chip-tester-english/

    which I just received.

    Time to order the components to fill this very nice set of boards !

  • Some updates

    sxpert • 04/12/2022 at 15:02 • 0 comments

    I made a new component for the board and gold fingers, and modified the first board to use it.

    Also, I dumped it all into a new gitlab project.

    enjoy !

    I'll be ordering boards when some money shows up. will have more pictures then

  • First board fully routed !

    sxpert • 04/05/2022 at 19:50 • 0 comments

    There, took some time, but the first board (the DAP, DAta Paths) is fully routed

  • Fixing up first bug

    sxpert • 04/04/2022 at 15:24 • 0 comments

    Turns out I was mistaken with the A=B situation.

    The pins on the ALU are open collector, this does a wired AND, which is incredibly slow (as suspected).

    So, what I had needs modified, and this appears to be more appropriate. The R11 / R12 value is debatable though, maybe the classic 1k value would be good enough ?

  • First board started !

    sxpert • 04/03/2022 at 09:55 • 0 comments

    So, how do we go on doing this ?

    Well, download the document here for the KB11-C processor boardand start page 1 😎

    First board is the M8130 DAP (Data Paths) which contains the 16 bit integer ALU and related multiplexers.

    Schematic capture is done.

    There is one thing that looks wierd to me in the original schematic, namely, the ALU chips (74S181) A=B ouputs are tied together with a pair of resistors to pull the line up/down, sure looks like a wired or hack...


    So I decided to add the possibility to replace this with proper or gates (a 74S02 would add 5.5ns, which I don't think is so much delay that it'd break things)

    Same thing happens in the generation of "BUS A=B (15:08) H"

    Of course, the board could be populated with more recent parts such as ACT for all functions that currently exist in this family.

    I have now started routing the board. about 50% done right now.