A Lisa Inside An FPGA

[ried]

I don't have a scope, but am happy to give it a try. What kind of scope should I use (any suggestions?) and how would I probe that particular signal?

[Lisa2]

When I received my LisaFPGA board the first thing I wanted to try was get it connected to the modern internet.  I was hoping to use Localtalk (MacIP), but then I learned that the hardware for Localtalk was not implemented on LisaFPGA. 

So for plan "B", I am using a PPP connection over RS232 at 56K baud.  I am running MW+II, System 6.08, MacTCP, MacPPP.  Connecting to a PPP server running on a Raspberry Pi 3.

With this setup I can run NCSA telnet and have multiple terminal sessions running at the same time.  NCSA telnet also supports FTP file transfers. The TCP/IP stack is running directly on the LisaFPGA hardware.  Works great!

Rick

[AlexTheCat123]

I don't have a scope, but am happy to give it a try. What kind of scope should I use (any suggestions?) and how would I probe that particular signal?

If you've got a logic analyzer, that would work too. I wouldn't want you to buy a whole scope just for this, especially since the problem is almost certainly my fault not yours! You'd want to probe the PWM line on the Sony floppy connector (J3), which happens to carry MT0 when it's in Twiggy mode. PWM is pin 20 on the floppy connector, so if you find the text on the PCB that reads J3, it's the connector pin that's immediately above there, on the inner column of pins.

I would just probe it myself on my board, but the Twiggy floppy controller won't emit pulses on MT unless it detects a disk in place, and since I don't have any real Twiggy drives, I have no good way to spoof disk in place without screwing up the other SNS registers too.

I've looked over my code again and I don't see any problems, so it's got to be something stupid that I'm overlooking. Just to rule out the drive, can you swap things around and plug your upper drive into the lower connector and your lower drive into the upper connector and see if the problem switches drives? And @sigma7, if you could confirm whether or not both of your Twiggies spin with the new LisaFPGA code, that would be great too.

When I received my LisaFPGA board the first thing I wanted to try was get it connected to the modern internet.  I was hoping to use Localtalk (MacIP), but then I learned that the hardware for Localtalk was not implemented on LisaFPGA. 

Yeah, unfortunately I couldn't find a good modern source for the differential driver ICs that you need. So I left that functionality off the board, under the assumption that practically nobody would actually use it. Clearly I was wrong; sorry!!!

As a side note, how did you get your PFG working in the SCC socket? Did you revert to my old code that uses the external SCC, or did you modify the new code to make it switchable between internal/external? Either way, it's really cool to see someone use a PFG with the board; I think you're the first person besides me to actually try it!

[bmwcyclist]

When using a USB keyboard with the FPGA, what key is the "CLEAR" key?

[bmwcyclist]

When I received my LisaFPGA board the first thing I wanted to try was get it connected to the modern internet.  I was hoping to use Localtalk (MacIP), but then I learned that the hardware for Localtalk was not implemented on LisaFPGA. 

I was always confused about that. Is it true that the LISA/LOS had some precursor to AppleTalk?

It would be phenomenal to get LOS on GlobalTalk, even if just a client!

[AlexTheCat123]

When using a USB keyboard with the FPGA, what key is the "CLEAR" key?

It's NumLock.

[bmwcyclist]

When using a USB keyboard with the FPGA, what key is the "CLEAR" key?

It's NumLock.

Thanks!

[stepleton]

Is it true that the LISA/LOS had some precursor to AppleTalk?

There was something called AppleNet, for which there was a dedicated expansion card. It never saw production use. During his experiments compiling the Office System, Alex reported finding some vestigial code for what looked like networked fileshares (if I recall correctly), but it obviously didn't work without the hardware, and enabling it led to some breakage.

[AlexTheCat123]

There was something called AppleNet, for which there was a dedicated expansion card. It never saw production use. During his experiments compiling the Office System, Alex reported finding some vestigial code for what looked like networked fileshares (if I recall correctly), but it obviously didn't work without the hardware, and enabling it led to some breakage.

Yep, and I think it was only 20 lines of code or so, all in the Desktop Manager. Basically enough to show the icon for the fileshare and break the OS, and that's about it.

[slewis1962]

I tried hooking one of my Twiggy drives up to the LisaFPGA but it crowbarred my power brick. My power brick can supply 3A @5v so it should be adequate. The LisaFPGA was not damaged as it worked after I unhooked the Twiggy drive and reset the power brick. I need to check and see if any of the tantalum's are shorted as that is one of the components that I've had to replace in the past when troubleshooting Twiggy drives. My drives have been sitting on a shelf for 6 years so I need to get a real Lisa out to test them before I go further. They literally have not been used in that time so anything could have happened. I did extensive testing to make sure my cables were correct and not backwards. I'll update when I get time to troubleshoot these drives.
I even had my scope out to check the motor signal. Oh well.

[ried]

Yeah, I used several USB-C chargers, battery banks and power bricks. All delivered the standard 5Vx3A=15W of power and it's simply not enough to drive a Twiggy.

[slewis1962]

Yeah, I used several USB-C chargers, battery banks and power bricks. All delivered the standard 5Vx3A=15W of power and it's simply not enough to drive a Twiggy.

My power brick is a 65W laptop power supply. It only supplies 15W at 5v though. I'm not going to buy any other power supplies, I'll use the FPGA board with ESFloppy and ESProfile and use my real Lisa if I need to use the Twiggy drives. I may redesign the Twiggy breakout board to accept external 12v at some point in the future if I get a wild hair...
I still need to test my Twiggy drives in a real Lisa at some point in the near future.

[slewis1962]

I have an update to my earlier post. I found the one drive I initially tried has the 12v rail shorted to ground. I found one of the tantalum's was shorted. I tried the other drive in both the upper and lower positions on the twiggy breakout board. Upon initial power to the FPGA board the motor spins for several seconds. Once booted into LOS 1.0 the drive no longer responds. I inserted a Twiggy but the drive fails to clamp down or spin the motor. I may investigate further later or I may just use this board without connecting any drives. I was all set up to test the signals with my scope but didn't get that far.

[slewis1962]

I do have a bench power supply that can deliver 0-30v at 0-5A. Is 5v at 5A, or 25W, enough? I'd rather not fry my FPGA board though. What is the absolute safest way to connect it to the board?

[AlexTheCat123]

I do have a bench power supply that can deliver 0-30v at 0-5A. Is 5v at 5A, or 25W, enough? I'd rather not fry my FPGA board though. What is the absolute safest way to connect it to the board?

Yeah, I think that's a good next step. Clip your ground lead to one of the ground lugs on one of the serial ports, the mouse port, or the ProFile port, and then connect the 5V lead to the center terminal of SW1, the power switch. That should be perfectly safe; just make sure you've got the voltage dialed in first and that you've fixed the short on your Twiggy drive!