Re: [midatlanticretro] 704k??? And boards, boards, boards...
> However, it could be set to anything that the chipI assume you're talking about the interrupt vector
> can address using a simple
> program to twiddle the appropriate bits in DOS low
table. I was aware that you could interrogate certain
locations to determine how much memory was installed
(which initially was determined by dos? then put there
I guess). I didn't realize it was that easy to bump up
the memory. Very interesing...
A good book to learn some of this stuph is "Inside
the IBM PC" by Peter Norton. There were a couple of
different versions. Back in the day I owned the
larger, revised copy I guess (looked great too).
Somewhere I have an earlier, smaller version.
> The program I used to set the memory limit wasRight. The Peanut used "VGA" circuitry to vary the
> intended for the PCjr where it
> was fairly common to stuff in over 800K. The jr
> used system RAM for the video
> buffer, so the memory 'adjustment' program also
> moved the frame buffer up and
> out of the way. If there are no ROMs in any side
> cars (ie: no hard drive
> adapter, etc.) then a jr can hold 896K RAM using at
> least one third party RAM
> expansion side car. Subtracting 32K for the video
> frame buffer leaves 864K
> for DOS.
location of video ram, yet making it appear to be
where standard CGA memory was supposed to be. VGA here
meaning video gate array, some funky logic, not the
later video standard we've all come to know and love.
ANOTHER GOOD BOOK ;) is "the IBM Personal Computer
from the Inside Out" by Sergent and Shoemaker (not
sure of exact spellings or title). The first edition
goes into the Peanut, later versions either supplanted
coverage of the AT or later the PS/2's.
> This biggest limit to this technique is that DOSNot personally aware of any aftermarket expansion
> memory must be a single
> block of RAM. The video frame buffer generally sets
> the upper limit to this
> game, however option ROMs can also get in the way.
into the A and B blocks, but it's an interesting
trivia question. Can't see any outfit making stuph to
go into the B (CGA & MDA) area, unless it was a video
card to replace the others altogether. Still haven't
found the time to play with my Vermont Microsystems
graphics card. It's a dual card similar I guess to
IBM's Professional Graphics Adapter (PGA). Mine has an
onboard 80188, the PGA had an 8088 I believe. Wish I
had one of those bad boys. No, VM is not what you'd
call a famous player in the PC marker, but if you do a
search, you'll find info about them taking Autodesk to
court over the use of some funky triangulation
algorithm, brought there via sneakernet (i.e. they
hired a former employee of VM). They won too.
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around