Restoring my Final Grail Item - The Resurrection of a Lisa 2

[Drake]

@warmech I've just started to move over components to the new PCB pictured below. JUST noticing now that the original has resistors added onto the parallel port while the new PCB doesn't include this. I'm wondering what the purpose of these were/are they necessary?

 

[retr01]

I didn't realize Lisa had an optional board with video output. Is that 1-bit TTL out?

 

[warmech]

@warmech I've just started to move over components to the new PCB pictured below. JUST noticing now that the original has resistors added onto the parallel port while the new PCB doesn't include this. I'm wondering what the purpose of these were/are they necessary?

Jokes aside, I'm wondering if those were just to prevent wonky power situations from damaging the parallel interface logic... That looks like one of Alex's boards; I'll reach out and see. They may not be necessary, but I don't know that I'd run without them.

 

[warmech]

I didn't realize Lisa had an optional board with video output. Is that 1-bit TTL out?

Heh, not an "optional" board, unfortunately - the Lisa backplane just pipes the same TTL video signal that goes to the CRT out to an RCA jack for connection to a TTL-capable display.

 

[retr01]

Heh, not an "optional" board, unfortunately - the Lisa backplane just pipes the same TTL video signal that goes to the CRT out to an RCA jack for connection to a TTL-capable display.

Cool!

That means the RGB2HDMI Raspberry Pico solution can hook the Lisa to the modern screens. I have a Power R TTL video out adapter for my SE/30 and will be working on hooking up my RGB2HDMI to one of my modern screens. Exciting! 1-bit computing is fun!

Hey @Mu0n! Check this out! Another 1-bit fun project.

 

[compu85]

The video out is actually composite - I've used it to drive a modern LCD projector. It's not NTSC timings... it matches the Lisa's resolution. It's close enough to EGA that some InFocus projectors can sync to it.

 

[retr01]

The video out is actually composite - I've used it to drive a modern LCD projector. It's not NTSC timings... it matches the Lisa's resolution. It's close enough to EGA that some InFocus projectors can sync to it.

I am unsure if the video out with the Lisa is a composite video since it signals at 22.7 kHz, which is higher than the composite video. See the last part of this page:

This documentation is available here on TinkerDifferent as Good Things to Know About Lisa.

 

[compu85]

It's composite in the sense that it's a single signal with Hsync, Vsync, and video all in one. It's not NTSC timings, but the signal is laid out like mono NTSC.

https://twitter.com/i/web/status/997151298914082823

-J

 

[warmech]

It's composite in the sense that it's a single signal with Hsync, Vsync, and video all in one. It's not NTSC timings, but the signal is laid out like mono NTSC.

https://twitter.com/i/web/status/997151298914082823

-J

Huh - TIL. That's pretty awesome! What model InFocus did you use?

 

[retr01]

It's composite in the sense that it's a single signal with Hsync, Vsync, and video all in one. It's not NTSC timings, but the signal is laid out like mono NTSC.

https://twitter.com/i/web/status/997151298914082823

-J

That is cool! Thank you, @compu85, for sharing that picture of Lisa projecting on a modern projector.

I think I did get confused between video signal frequencies and scan line frequencies since those two are different rates.

 

[compu85]

Some more details on how I hooked up the projector:

https://twitter.com/i/web/status/1441753530872713226

The one I'm using is an InFocus IN118HDa.

-J

 

[retr01]

Some more details on how I hooked up the projector

You should create a new thread here on TinkerDifferent and document your adventures with the Lisa, including the video out through a projector.

@compu85, have you tried hooking up the Lisa to a modern monitor to VGA or HDMI via conversion such as the RGB2HDMI with the analog add-on board?

RGBtoHDMI Video Interface Board For The Raspberry Pi Zero

Non-US Buyers: I am not responsible for additional customs or other payments you may incur due to international shipping. Help! I can’t find a Raspberry Pi: Try this The RGBtoHDMI Video Inter…

retrohackshack.com

 

[compu85]

Jokes aside, I'm wondering if those were just to prevent wonky power situations from damaging the parallel interface logic... That looks like one of Alex's boards; I'll reach out and see. They may not be necessary, but I don't know that I'd run without them.

They aren't there on early versions, but I have a (I think) rev G motherboard which does have them. It did seem like some filtering or protection. It was all manual rework too... the original traces were cut and the resistors added in!

 

[warmech]

They aren't there on early versions, but I have a (I think) rev G motherboard which does have them. It did seem like some filtering or protection. It was all manual rework too... the original traces were cut and the resistors added in!

Mine has them as well, and just like yours they are spliced in manually. Alex's must have been an earlier revision.

 

[fstark]

@warmech I've just started to move over components to the new PCB pictured below. JUST noticing now that the original has resistors added

In "Good Things To Know About You Lisa" :

Item 22:

22 Lisa 2: Possible Problems With The Upgrade K

This article last reviewed: 9 November 19

1. Symptom: Operating system error 10726, or error 8

Problem: Bad motherboard-ProFile interaction. Solutions: A. Replace the motherboard with an upgraded one. (Upgraded motherboards are distinguished by resistor packs around the parallel port.)

(Wondering about the state of your Lisa, though)