Updates, Distractions, and Failures

 Updates, Distractions, and Failures

I dropped my phone over the last weekend and spidered the screen.  That was a disappointing failure.  New phone should be arriving today.  Apologies for the potato photos that follow.

PCB Update

I put in an order for 4 new boards weekend before last, and they showed up this past Tuesday, which was cool.  In that order were:

• COREplus r0.2
• SystemIO r0.2
• ITX CORE Daughter Card (a.k.a. the CORE Mezzanine) r0.1
• ATX Power Adapter/Switcher r0.1

New boards!

All the boards arrived, and appear to be manufactured as designed.  That's good.  Thanks, JLCPCB!

I assembled one of the COREplus r0.2 boards, and it works.  Power-on Reset works without bodges, and the blinkenlights work.  So, that's good.

COREplus r0.2 - BLINKENLIGHTS!

I did some continuity checks on the SystemIO r0.2, and it turns out I messed that up.  The silkscreen issue with the "future peripherals" headers has been resolved, which is great, but it looks like I messed up on the RS-232 fixes, so all 5 ports still have the reveresed TXD and RXD lines between the MAX232s and the respective DB9 connectors.  I DID fix the problem in the schematic, but, apparently, I got distracted and never updated the PCB in KiCAD.  That has been remedied, and so, in r0.3, there should be no bodges required (for that, at least).  A mistake I hope never to make again.

I assembled one of the ITX CORE Daughter Card r0.1 boards, and it appears to be working-ish... the CPU, RAM, and ROM are all appearing to do stuff.  ...that is, once I put the clock oscillator in the right way (after cooking 3 of them -- not my proudest moment).  Unfortunately, hooking up a Jenny-O with the 6551 daughter card is, so far, not yielding communication.  I'm investigating.

ITX CORE Daughter Card r0.1 - Can it be saved?

I have not yet assembled the ATX Power Adapter/Switcher r0.1.  Might get stuck in to that this week.  It is not my highest priority at the moment.

CoreROM update

I've been working on a disassembler for inclusion in the CoreROM.  The way it would work is you put a start address and an end address in some special spot in RAM, and it will pick out the opcodes, match them to the mnemonics, recognize how many arguments that opcode should have, see if there's any "decoration" (like ",Y" or ",X" or " A"), and display the mnemonic, the decoration (if any), the opcode and the arguments (if any).  This has been slow going.  Putting together the lookup tables to get the opcodes and argument counts manually was a total pain, and I think I messed it up.  I went back to the drawing board, and wrote a Python tool to build the lookup tables.  That seems to have worked a treat, but I think I'm having a problem with a subroutine call maybe nuking a register somewhere along the way.  Debugging continues.

RIBBBIT65 ITX update

As I was poking around on DigiKey and Mouser, I found IO connectors I think I'm going to use, which is good.  I'm looking at double-stacked DB9Fs for the general purpose RS-232s, a single DB9M for the console, and double-stacked DB25Fs for the 2 general purpose VIAs.  While I was on Mouser's site, I discovered that they sell WDC's product line -- like the whole thing, apparently.  Looks like they have the W65C02, W65C22, and W65C51 in PLCC.  I poked around a little more, and discovered that, even in THT sockets, they are quite a bit smaller than the DIP40s and DIP28s I've been using so far.  I can fit almost 3 PLCC44s in the space of one DIP40 (in terms of board real estate).  If I go that route for the WDC chips and the EEPROMs, and SMT for the MAX323s and RAM, I might be able to fit the CORE and SystemIO on one MiniITX board.  It will certainly be more expensive than using dual-wipe sockets on DIP chips as I have been so far, but in a Mini-ITX form factor, that might be excusable.  I'd probably have to do a mezzanine card for the "Pageable ROM" and maybe a 3.5" External Bay thingy (prolly 3D printed) for the Cartridge Slot as options, but that's still pretty cool.  I'd be curious to hear your thoughts.

So, as of early December, that's where we are.