Re: [N8VEM: 14723] Xi 8088 - The improved version of my XT board

[Douglas Goodall <douglas...@mac.com>]

Al,

I have a huge pile of AST Rampage boards, some of which are ISA 8-bit, and would
provide several megs of extended or expanded or backfilling memory.

Also a number of small boards meant to backfill 640K.

If any of these would be useful to you, let me know...

Douglas Goodall


On Sep 25, 2012, at 4:00 PM, ..I'd rather be coding ASM! <uri...@deviate.fi> wrote:

> 
> Hi Sergey,
> 
> Interesting. I've an old amstrad 286 I've recently got working again and have been playing with UMB/EMS memory windows in tasm. I also have an Orchid Turbo 286 board I've previously had working in an NCR PC 4i
> and am dead curious if it'd work in the V1 sergey XT hence the tyre kicking.
> 
> A UMB/EMS board would be *very* nifty.
> 
> Thanks. :)
> 
> Al.
> 
> On Tue, 25 Sep 2012, Sergey wrote:
> 
>> Al,
>> 
>> The Xi board allows mapping some RAM above 640K in 0C0000h - 0EFFFFh
>> area, providing up to 192 KiB of UMBs. Part of this area might be used
>> by BIOS extension ROMs or for memory mapped I/O, which limits the
>> usable space. For example VGA cards normally use 0C0000h-0C7FFFh block
>> for VGA BIOS.
>> 
>> It is possible to eliminate other ROMs (such as XT-IDE BIOS) by
>> copying them to the BIOS ROM at 0F0000h-0F7FFFh area (memory above
>> 0F8000h is used by the BIOS itself). This will not only save UMB
>> blocks, but also the ROM ICs for XT-IDE BIOS (or network boot ROM).
>> 
>> I actually tested the UMB with V1.0 board, using USE!UMBS and DOSMAX:
>> http://ftp.sunet.se/pub/simtelnet/msdos/memutil/use-umbs.zip
>> http://ftp.sunet.se/pub/simtelnet/msdos/sysutl/dosmax21.zip
>> 
>> This is pretty cool, as it relocates DOS and related stuff to UMBs,
>> leaving about 625 KiB of usable lower memory.
>> 
>> Implementing a real EMS (with switchable pages) would require more
>> components, and I didn't want to over-complicate the design. But an
>> EMS card is an interesting idea for another project.
>> 
>> Thanks,
>> Sergey
>> 
>> On Sep 25, 3:09 pm, "..I'd rather be coding ASM!" <uri...@deviate.fi>
>> wrote:
>>> On Tue, 25 Sep 2012, Sergey wrote:
>>>> Good. In this case I'd like to know who else will be interested in
>>>> making a backplane?
>>> 
>>>> I'll start a separate thread to discuss this.
>>> 
>>> I'd be super keen to build one. Some suggestions:
>>> 
>>>   - ATX holes so it can be bolted to easy to find PC cases
>>>   - AT and ATX connector
>>> 
>>> Separate idea.. with the XT v2, is there a way to get 64k EMS to work?
>>> Wondering if there's a RAM expander anyone's tried from the v1.
>>> 
>>> Al.
>>> 
>>> --
>>>   --
>>>   Al Boyanich
>>>   adb -w -P "world> " -k /dev/meta/galaxy/ksyms /dev/god/brain
>> 
>> 
> 
> -- 
> --
> Al Boyanich
> adb -w -P "world> " -k /dev/meta/galaxy/ksyms /dev/god/brain
> 
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