Re: 5mhz lisa to 8mhz?

The X/ProFile can be substantially faster than the Apple ProFile, so it does provide a performance boost for the Lisa Office System. However, some CF cards are faster than others, so the actual improvement varies with the media used (the transfer rate is not important here, it is the read/write latency that affects the X/ProFile response time, but CF cards with a faster transfer rate tend to be faster in other respects too).

It might be possible to enable the XLerator 12.5/18 for use with the Lisa Office System, but the difficulty depends on how LOS uses the Lisa's memory management circuitry.

The XLerator uses a "shadow memory" technique so the fast RAM (which provides most of the speed boost) is accessed before any MMU translation takes place (which also improves speed).

Does anyone know if data/code in memory is "moved" around by LOS using the MMU in some complicated way, or is the memory selectively paged/mapped to different logical regions just because there isn't enough of it?

James

Des wrote:
>I would imagine, someone correct me if I am wrong here but you are
>going to see much greater speed increases by using one of the
>X/ProFile drives with a CF card. Rather than trying to overclock the
>CPU by a few Mhz

Barana wrote:
>so could we modify an Xelerator or another accelerator to work with
>lisaos ?
>
>> > I remember reading apple slowed down the Lisa to 5mhz as the ram in
>> > the quantity needed to talk to a 8mhz 68000 was prohibitive.
>> > Is it possible to upgrade the ram to something that can handle 8mhz
>> > and bring the 68000 up to 8mhz?

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