General Category > LisaList2

New CPU, I/O, & Motherboards for Lisa 1/2 and Lisa2/10

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sigma7:

--- Quote from: diogenes on September 26, 2023, 05:26:53 am ---another source for a suitable Quarz oscillator:

https://centuriontech.eu/product/customized_oscillator/

Is this a good company?

--- End quote ---

I'm not familiar with them; there is this topic on an amiga forum:

https://eab.abime.net/showthread.php?t=111328

sigma7:

--- Quote from: diogenes on September 24, 2023, 09:15:28 am ---purchased an unpopulated Sapient  Lisa CPU board...

where can I get these BOOT ROM's 4X EVEN and 4X ODD? And where can I get the Video ROM MASTER 4x ?

--- End quote ---

The Sapient Lisa CPU design has an integrated ROM switcher, which means you have the option to install larger than usual ROMs that contain multiple CPU ROM versions. eg. Rev H and 3A would be likely choices. The switches on the CPU board then facilitate switching between those versions without changing any parts.

The standard/original size of CPU EPROMs is (a pair of) 8Kx8 (2764). The ROM switcher supports EPROMs up to 64Kx8 (27512) which provides enough room for 8 versions. The video PROM socket supports a double size PROM (512x8), so two versions of the video PROM can be used (typically one would select one for rectangular pixels and the other for square pixels).

The 4X naming refers to a set of ROMs containing 4 versions. I believe the current 4X ROMs that Vintage Micros is currently putting on their assembled CPU boards contains
versions H, 3A, D, C, but I expect this may change in the future once it is established which versions are most useful.

You can install stock/original CPU Board ROMs if you wish.

Details about combining ROM images will be in a future post. Beware that when combining Video PROMs into a double size one, the two are not consecutive in the PROM.

Now corrected: (There was an error in the drawings below when they were first attached; at the bottom right it should read "SW1 On = A13 low" (not A15 low))

patrick:

--- Quote from: diogenes on September 26, 2023, 05:26:53 am ---Back to the unusual frequency- could it be possible that it had something to do with the US TV Colour norm (...)

--- End quote ---

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.

diogenes:
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!

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

CT1954MST-ND

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