pentiumspeed wrote on 2023-02-10, 02:38:
I can attest, I had MBC-555, Not fully compatible and comes up to 256K only using 64K x 1 chips, no ISA slot or ISA signals provisions. Due to not quite compatible, I had less interest in it. Back then I was given three MBC-555 computers with no options, floppy drives only, with office software. No games to play on and that was in 1989 or so. The bios is loaded into computer via boot disk during start up. Keyboard nonstandard too.
Did people figured out to modify MBC-555 into fully compatible XT complete with 360K and executes standard Dos 3.xx and standard games without issues?
Cheers,
"It's not a bug, it's a feature"
The computer line is from 1982..
Before 1985 or so, IBM was no authority in the microcomputer market.
It rather was Microsoft, well known by its BASIC products - and MS DOS.
Edit: Microsoft also tried to make a name as an Unix specialist for itself at the time.
Microsoft had Xenix as its flagship product.
Up until version 3, MS-DOS was sold to the OEM market, where it was modified for custom hardware.
In the early 80s, there were not only IBM PC-compatibles, but also MS-DOS compatibles (a forgotten breed).
PCs that were on purpose not a 1:1 copy of the IBM PC.
Not seldomly their companies tried to make better than IBM.
Better audio/video capabilities, unconventional floppy drives,
different/faster serial ports (non-8250 based),
16-Bit slots or a higher performance 80186 based design (non IBM compatible SoC).
Examples: Tandy 2000, Siemens PC-D, Sirius-1/Victor-9000, Olivetti M24 (IBM compatible, but with proprietary 16-Bit slot extension),..
https://www.homecomputermuseum.nl/en/collecti … ndy/tandy-2000/
https://www.homecomputermuseum.de/sammlung/de … /show/sirius-1/
https://www.retrospace.net/infoseiten/readm.php?id=48
http://www.duensser.com/pc_pcd
http://oldcomputer.info/pc/SiemensPCD/index.htm
Of course, to the untrained eye, the pure consumer, these PCs are inferior.
Because they don't imitate IBM's defects.
Unfortunately, the 80s and 90s were full of poorly written IT articles and magazines which didn't remember this aspect of history.
And so in our collective memory we learned and accepted that non-IBM compatible PCs
solely existed due to sheer incompetence of the other PC makers of the time.
Not considering the Taiwan clone makets of cheap IBM PC mainboards and accessories that had no trouble making duplicates.
And not considering how primitive the IBM 5150/5160 design really was at its core.
Every IT student could have come up with that, if needed.
The "ingenious" BIOS idea could have been borrowed from CP/M.
With the PC slots were borrowed from Apple II.
"To stay young requires unceasing cultivation of the ability to unlearn old falsehoods."— Robert A. Heinlein.
I mean, let's just look at the 555's bootable BIOS..
Its functionality could be updated by simply booting a different floppy diskette.
- Oh and it saves production costs (small boot ROM) and doesn't occupy precious address space permanently ("clean computer" concept). 😁
An XT by comparison had to have its ROM set replaced for an upgrade,
which wasn't easy to do for the laymen at the time.
If the Sanyo PC machine was accepted back then, a few more software releases may have been available, too..
http://www.computinghistory.org.uk/det/8932/Sanyo-MBC-555/
Edit: Just double checked this posting. I find it not to be very good.
So I feel the the need to say: Please don't get me wrong.
My response was not meant as an criticism to pentiumspeed in any way .
What I wrote were my thoughts on the topic/matter only.
MS-DOS compatibles are a piece of history in their own right, I think.
On the internet, they are too often being considered as failed IBM compatible PCs.
Which, however, was something not all manufacturers aimed for (PC compatibility).
Some MS-DOS compatibles were aimed torwards a special application.
Say, being a fast platform for running AutoCAD, dBase or Lotus 1-2-3.
Those PCs were sold with modified versions (ports) of such business software.
That's what they were primarily designed for.
Of course, having the ability to run other DOS applications was favorable, too!
That's why these BIOS simulators were being written.
To also support certain DOS utilities or internal company software.
However, these simulators were not beibg written to be running all the time.
The IBM PC personality was more of a masquerade, an imitation of a foreign accent.
Otherwise, the computer was designed to be IBM PC compatible right from the start.
"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel
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