LisaList2

Kelly, I have one if you still need it. Send me a PM.

Hello everyone.

Here on LisaList2 I think almost everyone likely already has a Lisa but to "whom it may concern" if you want to see the LisaOS or help me out with a display or presention....

In downtown Cincinnati, Ohio, next weekend I will have my Lisa 2/10 on display and will allow people to try out the LisaOS between my presentations.

If you would like to see and try a Lisa stop on by and if you want to volunteer, I can give you a code to get in free.

https://blog.cadre.net/step-back-in-time-tim-oconnors-vintage-hacking-demos-at-queen-city-con

A clean, tested original, or Sapient one? Trying to get one working, thanks!

I am stunned fantastic work thank you!!

That is astonishing. Congratulations, Alex! Looking forward to seeing it in the real world.

Wait, who is this new Lisa1 person? 

Hah, I wasn't paying attention and thought it said Lisa2! Do we have a new admin?

It's been a while, time for an update!

I'm getting pretty close to finishing the schematic for the PCB, and then I'll be onto the layout and routing phase. The whole schematic is done other than the connections of everything to the FPGA itself. Hopefully that shouldn't be too hard, I just need to look at the datasheet and make sure I connect certain Lisa signals to certain special-purpose I/O pins.

By the way, I've settled on the Xilinx Artix 7-100T as the FPGA of choice for the final board. It's pretty darn cheap at about $20, has plenty of LUTs, and between 200 and 400 I/O depending on which package you get it in. I'm currently using a little over 200 I/O, and this board doesn't even have expansion slots on it (which will add even more to that), so the 300-I/O version is going to probably be the chip of choice.

The key features of the board are:
- Power over either USB-C or barrel jack; 12V, -12V, and -5V (along with the 1V, 1.8V, and 3.3V FPGA voltages) are all generated onboard.
- USB port goes into an onboard hub chip, which feeds four devices: JTAG for FPGA programming and debugging, an onboard ESProFile, an onboard (yet-to-be-coded and I'm not even sure if I'll ever get it to work) floppy emulator, and a USB to serial chip that can directly feed the Lisa's Serial B port.
- As just mentioned, an onboard ESProFile and ESP32-based floppy emulator. There's a Floppy Emu-style OLED display and set of buttons for controlling floppy emulation, although once again none of that is implemented yet. And of course there are switches to choose whether you want to use the hard/floppy emulators or actual drives plugged into ports on the board.
- Switches to toggle between H and 3A CPU ROMs (and the corresponding VSROMs) and A8 and 40 I/O ROMs on the fly.
- The first version won't, but future versions will have Twiggy headers for the lucky few of you who happen to own a set of Twiggy drives!
- Onboard speaker (with the Lisa's 3-bit volume control) for Lisa audio, and external speaker header if you want to connect a larger one.
- Onboard contrast latch DAC in case you want to use the analog contrast signal for anything.
- HDMI video output. The VSYNC, HSYNC, and VID signals are also exposed on a header for easy connection of an RGBtoHDMI if you prefer that.
- USB keyboard and mouse input. As with the ProFile and floppy interfaces, these are switchable, so you can still plug in original Lisa keyboards and mice and use those too.
- Per James' suggestion, the Lisa's serial ports are implemented using a real 8530 SCC that you'll have to pop into a socket on the board once you receive it. But all the SCC's serial I/O pins are also bidirectionally level-shifted and run back to the FPGA so that a future version of the firmware can implement the SCC internally without requiring any changes to the PCB. The FPGA would just enable the level shifters, and that would take control from the external SCC.
- And as I mentioned earlier, Serial B is switchable between the actual DB25 port and a direct USB to serial interface with your computer, making it really easy to do things like transferring over all the LOS source code without needing a USB to 9-pin serial adapter and then a 9-pin to 25-pin serial cable.

There's no way that this thing will even come close to working on the first try, but hopefully I'll be able to figure out all the problems reasonably easily after getting a prototype run of boards in the mail.

As with some of my other recent designs, I've made sure that every part I'm sourcing is from JLCPCB/LCSC's parts library, so they'll be able to assemble the whole board for you when you order one. Which is pretty crucial given how much surface-mount stuff there is on here! The parts cost is currently looking to be a little over $100 per board, but I'm hoping to get it a little lower than that on the next board revision when some of the debugging hardware is removed.

It's still probably going to be a couple weeks before the layout and routing are done, but at least finishing up the schematic means that I'm about halfway there now!

Wait, who is this new Lisa1 person? 

Oh nice, it's awesome to see a clone of the RAMStak! I've been wanting to clone it for a while, but it looks like you beat me to it. Are you planning on publicly releasing the files anywhere?

Well, regarding the 2MB question, I do have a working solution.