Parts ordered for the A501 replacement card

I placed an order yesterday for some prototyping parts to get this project off the ground.

Some of the key parts are:

  • ISSI 256kx16 SRAM chips. IC SRAM 4MBIT 25NS 44TSOP
  • A surfboard to do 44-pin TSOP II to DIP.  Wish me luck soldering this one! .8mm between pins. (highly recommend for these types of adapters!)
  • Some 56-pin dual row 2×28 female headers .1 on center and row. CONN FMALE 56POS DL .1″ R/A GOLD
  • Some 74LS logic chips.  Hopefully this will be fast enough, but if not, we go to ALS!
  • Another solderless breadboard. More wires.

I want to get these in, get that memory chip soldered, get the logic chips on the boards, get them wired up.  I want to test the logic to make sure the timing is correct prior to even attaching the SRAM chip — and certainly before it gets attached to the Amiga.

I’ve got a preliminary schematic drawn up, but I’m not publishing anything until I’m reasonably certain this is going work!



Amateur Electronics Design Engineer and Hacker


  • Hello Keith, Congratulations on designing your own 501 board. It is inspiring to see how you tackle this issue by issue and resolve each by trial and error. Myself I’m only beginning to scratch the surface of my Amiga-diy skills.
    I would like to try and make your board. I’m probably not looking where I should but cannot find the pcb schematics. Or do you prefer that I purchase boards from you?
    Greetings, Bjorn