[Coco] VCC, MMU & AWE

[Walter Zambotti]

Hi guys/girls

I've being tinkering with VCC in view of optimizing the emulation.

I have identified a number of areas where dramatic improvements may be possible.

One of these areas is with the MMU emulation. Currently in VCC this is emulated completely via software. With the page/block mapping requiring an address translation  for every memory access.

Windows provides physical memory page mapping support via hardware. AWE Address Windowing Extension provides support for mapping any number of 4K memory pages in and out of any size window (64K for instance).

This hardware mechanism works very summarily to the GIME MMU. This would allow hardware to be used to emulate hardware directly.

In my first experiment I have replaced the standard malloc'd memory for AWE VirtualAlloc memory. 

The VCC emulator still works!!!

This is a good sign.  I can now work on converting the MMU bank register routines and the memory access routines.

Once I have the memory access routines optimized this will can convert a typical memory access from:

Byte = Memory[MMUBanks[Mode][Address>>13]][Address&0x1FFF];

To:

Byte = Memory[Address];

Since that is what the 6x09 spends nearly all its time doing this should make a substantial improvement.

However I have already tested AWE support in WINE (Linux) and it is not there so until the function stubs are fully implemented this would be a Windows only modification!!!

However I am only using three AWE functions and Linux provides the mremap function which may make it possible to allow rudimental AWE support.

Walter

-----Original Message-----
From: Coco [mailto:coco-bounces at maltedmedia.com] On Behalf Of camillus gmail
Sent: Monday, 12 June 2017 10:30 AM
To: Bill via Coco <coco at maltedmedia.com>
Subject: Re: [Coco] postage

Hi JoLaJaKa!

I'm sorry all is gone.

cb
On 6/10/2017 9:19:17 AM, JoLaJaKa! <jolajaka at gmail.com> wrote:
Are there any extra 6309's from your orders?

I'm a little late jumping on this!

Thanks,
John

Sent from my iPhone

> On Jun 9, 2017, at 9:28 AM, camillus gmail wrote:
>
> Hi all,
>
> In the assumption that everyone have the ordered CPU's, I send this reminder to take care of the postage. The amount that is on the envelope is the amount I paid to the post office. As up this moment I'm short of 10 payments. I'm sure this will be corrected soon.
>
>
> Thx All
>
> CB
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> --
> Coco mailing list
> Coco at maltedmedia.com
> https://pairlist5.pair.net/mailman/listinfo/coco

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