LisaList2

The EPROMs on the CPU board should have access times of 350 ns or below. However, I have also seen 3A ROMs from Sun Remarketing with 450 ns.

The video state PROM is driven by the dotclock, so it must be faster than 50 ns.

The floppy ROM is running at Apple ][ speed, so 450 ns is sufficient.

ROM switch? It seems to be a right angle 4 pole SPST DIP

A perhaps subtle detail is that switch 1 of the 4 is at the end closest to the 68K CPU.

Up on or Down on doesn't matter as long as you know which is which.

(IIRC there are right angle switches that are labelled in the opposite direction. A reverse numbered switch will work fine, you just need to be aware when setting it.)

The board also has a hole pattern for using a rotary DIP switch in lieu of the toggle/slide switch, but I don't know offhand which rotary switches would fit.

The Lisa community is pretty small, and it might be the case that one of the donors or even an organiser or cheerleader for the challenge (nb: I'm not speaking with you/sigma7 or anyone else specifically in mind here!) could be one of the winners.

Some people might be reluctant to contribute if they were worried about a conflict arising there, especially folks who are unfamiliar with us. ("What if one of these lisalist2 strangers had a working build all along, and this was just a way to make some easy cash?")

I suppose that could be a concern, so I (JDM aka Sigma7) officially remove myself from eligibility to win any of the prize.

If anyone spots any other considerations that could deter support for this challenge, please explain.

If someone does already have a working solution, I would consider them still eligible for the prize (including you TS ), as the task of documenting it is worthy in itself.

And can you tell me the DigiKey part # of the ROM switch? It seems to be a right angle
4 pole SPST DIP (as seen in the populated Sapient CPU board)

There are lots of possible choices for the ROM SW, so you can choose according to your preference.

The picture shows a right angle "piano" style switch, which may be the easiest style to adjust when working on the Lisa from the rear, but other styles will work fine too.

And, if you don't install any switch, it will behave as though all poles are open, which will work fine with stock/standard/original ROMs.

Is this the correct DIGI KEY part# for the DIP switch?

CT1954MST-ND

That switch will work fine. The T suffix indicates it has tape over it for automated soldering equipment, so you'll peel that off. If the same switch was in stock without the T it might be a few cents cheaper.

That brand is a light blue colour. Other brands in stock are priced similarly and come in Black, Red, or Blue. If you have a preference, you are welcome to send me a DM and I'll help you select one.

Is this the correct DIGI KEY part# for the DIP switch?

CT1954MST-ND

And can you tell me the DigiKey part # of the ROM switch? It seems to be a right angle
4 pole SPST DIP (as seen in the populated Sapient CPU board)

Thanks for any information!

What about a hybrid approach where half of the prize goes straight to the winner, while the other half goes to a computer museum of their choosing?

Or perhaps the person making the pledge can decide which is their preference?

I fear the task may be too big, which will prevent anyone from getting the prize, or worse, there will be duplication of effort for the initial part of the problem, then no further progress due to challenger burn out. Success may require sequential effort from multiple people.

So then:

Is there a way to prevent duplication of effort?
Is there a way to fairly allocate the prize among multiple contributors?

What about a hybrid approach where half of the prize goes straight to the winner, while the other half goes to a computer museum of their choosing? That way, both the people who are motivated by the cash prize and the people who want to make a feel-good donation to charity would be happy!

Back to the unusual frequency- could it be possible that it had something to do with the US TV Colour norm (...)

The video signal generated by the Lisa has a line frequency of 22.4 kHz and a frame frequency of 60 Hz. This is quite incompatible to both the US system M (15.734 kHz / ca 60 Hz interlaced) and the European BGI system (15.625 kHz / 50 Hz interlaced). Lisa has no color and therefore does not generate any color subcarrier.

The external video connector was hardly used in the '80s. According to Apple's documents there were two monitor types and one video projector for 22.4 kHz available from 3rd party suppliers.

Thanks for proposing this!

One variation on the prize scheme that might attract more participants (funders and maybe competitors --- but will motivate people differently) would be to have the cash not go to the winner but instead go to the winner's choice of reputable computer museum.

The Lisa community is pretty small, and it might be the case that one of the donors or even an organiser or cheerleader for the challenge (nb: I'm not speaking with you/sigma7 or anyone else specifically in mind here!) could be one of the winners. Some people might be reluctant to contribute if they were worried about a conflict arising there, especially folks who are unfamiliar with us. ("What if one of these lisalist2 strangers had a working build all along, and this was just a way to make some easy cash?")

The nominal benefit of giving a donation choice to the winner might seem like less of a conflict, and the person contributing to the pot of money also gets to feel good that the cash is going to a museum. This may encourage more people to participate as funders. (This is also one reason to restrict the winner's choice to computer museums --- presumably those are of interest to nearly everyone who might want to compete or fund, and funders can give freely without any worry that the winner might choose a charity that they find morally objectionable.)

I'm thinking too that a donation bounty might encourage more collaboration than a cash bounty. If a pile of money is on the line, then competing participants may not want to share secrets or tools so that they can maintain an advantage. If the prize is a donation choice, then a competition may stay friendlier and may go faster as participants may wish to try and get the cash to a museum (and get a working build) as soon as possible.

A donation bounty also has fine PR value I think, and while we're not trying to market ourselves per se, a "feel good" story like this may spread further than the story of a traditional bounty. A wider reach could attract more people into the Lisa community, and that could have all kinds of benefits: what if some hacker gets it done by sprucing up LisaEm's Workshop support in the process, for example?

Of course, the motivation of a small personal windfall will be absent with this scheme, and I don't think there's any shame if that's what drives you to take up this challenge!

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Moving away from the nature of the prize, we could also reward desirable modifications and improvements to the Office System, like ways to use different storage media, networking, fixing the Y1.996K bug, etc.

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Anyway, just some thoughts. Thanks again for drafting this!