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S > SANYO  > MBC-55x


This mini forum is intended to provide a simple means of discussion about the Sanyo  MBC-55x computer. If you want to share your own experience or memories, or add relevant information about this system: post a message! For other purposes like sales messages, hardware & software questions or information requests, please use our main forum.

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Tuesday 2nd April 2002
philip yanov (Greenville, SC)

I used to sell these machines. We wrote software for carpet cleaning companies that ran on them. I think these machines lacked DMA or something. WHat I remember was that every time you accessed the floppy drive, the real time clock stopped and then restarted when access was over. The more you used the floppy drive, the further the real time clock was off. Since it took about a minute to format a floppy for example, the clock would be a minute slow when you were done.

Sunday 26th July 2009
Adam Marchaud (Ohio, USA)

I put a lot of time and money into tricking out my old 550. Not only was it fun, but I learned a lot.

Wordstar as supplied was painfully slow, as it insisted on redrawing the screen completely with every scroll. A patch (which I think came from Soft Sector magazine) told it to use the BIOS screen writing routines, for a huge improvement.

My 550 also came with a different word processor, Easy Writer, which I tried once and put away.

The buzzer was not impossible to control, just limited. It was actually a speaker driven by a square wave generated by a programmable UART. Like Robert, I typed in somebody''s BASIC program, again probably from Soft Sector, or maybe from The Silver Box (the Computer Shopper Sanyo 550 column). The program would play something more or less recognizable as music through that speaker. Alas, it took so long to enter even a short piece of music that it wasn''t worth it except to prove it could be done.

One of the few PC programs which would run as-is was Mark DeSmet''s C compiler. The editor even worked after I relinked the executable, using BIOS routines to replace the direct screen writes. With that compiler and its basic non-macro Intel assembler, I wrote my own modem program with vt220 emulation, chat scripts, and xmodem protocol.

I wasn''t too interested in the $150-200 Sanyo video board CGA option and instead fitted a $30 Hercules monographics clone. Again using DeSmet''s Intel assembler, I wrote an MSDOS device driver to support it and its printer port, using the Sanyo''s original red and blue video areas in high memory for print spooling buffers. The device driver also added hotkey support so I could use Borland''s Sidekick. With that, I got a surprising number of supposedly incompatible PC programs to run on that machine. Eventually I patched the BIOS on the diskette to talk to the monographics card without the driver.

I probably still have the source code for most of those drivers and patches, if anyone cares.

Lots of folks piggybacked memory on the 550s to get 512k or 768k. I used a cleaner method that one of the hardware hackers in our local users'' group figured out. IIRC, we replaced the second 128k of memory with higher density chips for 512k, and tweaked the memory addressing to support the larger chips.

For a while, I ran two 800K Teac drives using Michtron''s DS-DOS, for a total of 1.6mb online floppy storage.

Later I fitted a hard disk kit which used a surplus SASI (Shugart''s SASI, not SCSI) controller and a custom board which plugged onto the Sanyo expansion bus and spoke SASI. I eventually put a 40mb Winchester drive on that box. I had to patch the HD kit''s driver for that enormous (!) disc, and replace Sanyo''s feeble linear power supply with a surplus switching supply to provide enough current. (A more common upgrade was fitting larger diodes to Sanyo''s linear supply.) As someone pointed out the Sanyo had no DMA, but since HD transfers were much faster than floppy transfers, at least the HD made PIO a little more tolerable.

I also added a clock speed doubler, a little "turbo board" which plugged between the CPU and its socket. With a NEC V20 replacing the 8088, that machine could almost hold its own against 8mHz PC clones.

I kept that little silver box going and useful up until about 1990, when I got my first 80386 machine.

Lots of great memories. I wish I still had the little guy, but I donated it to Amvets in a cleaning fit one day. I don''t want to know what they did with it.

Monday 25th August 2008
Steven Koehler

The floppy drives in these models were from Teac. Interestingly, the drive lights always stayed on when the door was closed. They did not go out even if the drive was not currently being accessed.

Regarding the video issue: a lot of "IBM PC" software at the time accesed the address of the video cards directly - B800:0000 for color and B000:0000 for monochrome, since the Sanyo had no video card at this address the video output was never seen. I believe Sanyo offered a CGA card that was present at this address for direct memory writing.

A-OK company wrote a OS for the system as well, called A-OK DOS.

My MBC-555 would reset by itself if the dishwasher started - I always wondered why, maybe it had to do with the type of power supply.

The IBM PC/XT at the time had 10 function keys. Notice the Sanyo had half that amount. To get the higher function keys you would need to do these strange shift combinations.

Thursday 16th November 2006
Mark Raftogianis (USA)

I bought a Sanyo MBC-555-1 iin 1983, primarily due to its low price and color capabilities. It came bundled with WordStar, CalcStar, and DataStar. BASIC was easy to program for graphics. My Sanyo had MSDOS v.1. I bought it from Priority One computers in Los Angeles; they had a big sale at the Los Angeles Convention Center. The Sanyo rep said they were creating an upgrade kit to convert from DOS 1 to DOS 2. Well, that upgrade kit never came. When I talked to Priority One they said they had numerous complaints about Sanyo's support and eventually severed ties with them. After 20 years I still refuse to buy Sanyo products! I eventually bought an IBM close to replace it. I donated the Sanyo to Goodwill.

Thursday 30th March 2006
Warren Watts (Columbus, OH)

I purchased an MBC-555-2 via mail order in 1985. I remember spending hours sifting through the Computer Shopper to find the absolute best deal I could.
I had an early version of Borland Turbo Pascal that I used on the machine. I remember writing a Pascal version of "Animals" that ran on the Sanyo.
During the time I owned the computer, the price of RAM dropped dramatically and I purchased the individual RAM chips necessary to max out the computer's memory. It took quite a few chips as I recall, and I remember painstakingly placing all the RAM on the motherboard.
In 1987, I traded it to my boss for an original 128K Apple Mac. He had a small software company, and used the Sanyo for several years afterward to copy and create distribution disks for his products.

Sunday 23rd April 2017
Paul Miller (USA)

I had an Atari 400 before this by the 550 was my first "real" computer. Like many others here I learned a lot about computers with it. I spent a ton of time on a bulletin board dedicated to the 550 in Michigan (Michigan Software I think?) over a 300 baud modem.

There was a 550-specific magazine at the time that I poured over every month. Someone published some assembler in there to control the speaker to make tones. I wrote a synthesizer/sequencer (callled Sanyo Synthesizer) using that and had it published in the same magazine, when I was in 7th grade. Someone also published some code to do smooth-scrolling and I used that to make a simple game with a space ship where you fly through some caves, and had that pubished as well.

The graphics were much better than the standard IBM PC and I wrote a lot of programs with colorful graphics and animation, spending a lot of time working out pictures on graph paper and turning them into bytes.

Sunday 2nd August 2015
willy tarreau (france)

I used to have an MBC-550 when I was a kid, from 10 to 16 (1984 to 1990). I learned a lot on it. Initially it was shipped with DOS 1.25, which didn''t even support directories. That probably explains why even today there are 4500 files in my home dir! After I accidently destroyed the boot disk, I received a DOS 2.11 floppy as a replacement, and could start to retrieve some MS-DOS 3.20 programs from the school, "crack" them to ignore the wrong DOS version, allowing me to run the wonderful DEBUG utility for the first time. That allowed me to start to write ASM. This machine was provided with a fairly complete manual including the whole schematics. I could write a PC-compatible BIOS that would boot MS-DOS 5.0 and run Tetris. However by then I didn''t understand how to write using the floppy controller (there was no internet to get datasheets), so disk writing was disabled, and tetris scores could not be saved. I could not use Turbo Pascal 3.0 either due to this lack of writing capability. For this reason I programmed this BIOS as well as a copy of the original on a 27128 EPROM with a switch on pin A13 so that I could decide what BIOS to boot from. I really had great moments with this machine, and its graphics were quite cool for that time.

Wednesday 18th February 2015
Brian Empey, P.Eng. (Canada)

Quirks :: to get the unit below $1000 retail, Sanyo cut a lot of corners. Someone mentioned that it was lacking a DMA controller. That is correct (I have full schematics of the motherboard, and all the original manuals with my MBC-550). In order to read or write from/to the floppy drive, it had to go into a tight SW loop, ignoring all else. Due to the limited memory, WordStar would buffer documents, and swap/load data from the floppy while scrolling or while you entered a lot of text. Users quickly learned that when typing in WordStar, once you heard the loud "Clank" of the disk heads actuating, its time to stop typing, because every character that you type will be lost while its accessing the drive.
I created a computer animation for a 4th year arts class at UBC on my MBC-550 with custom code that I wrote in BASIC. The animation was filmed with a borrowed 16mm camera with a single-step mode and a shutter release cable.
It was so slow rendering each frame that I had to add a "BEEP" at the end of the rendering to wake me up to capture that frame and hit the space bar to start rendering the next frame.
I generated about a 1/2 minute of 24 FPS film, but I recall it taking over 24 hours to do so.
Oh, the graphics buffers were very bizarre.
The chip''s BIOS was in a unique SANYO windowed EPROM chip that also housed the RED and BLUE video buffers. It only supported 640x200 graphics (16,000 bytes each, so 32k SRAM for RED and BLUE) housed in the same physical chip as the BIOS PROM. It had an RGB output, and a monochrome composite output that only showed the GREEN video. But the GREEN came from the main DRAM memory. So, in theory, you could do monochrome animations by pre-rendering frames into RAM and then re-mapping the video controller for where it should fetch the green pixels. Pretty cool! But I wasn''t ambitious enough to do that.

Monday 23rd July 2012
Gerry Brophy (canada)

I have an active Sanyo mbc 550 / 555 computer and I''m creating an archive of software for it.

Please let me know if you have any software to contribute so I can add it and of course check it out myself. I have mnay more disks that I am slowly adding to my archive.

I have a Sanyo mbc 555 w 2 disk drives, colour monitor, joystick, IBM Video Board and a bunch of disks.

Gerry Brophy

Monday 5th March 2012
chris (europe)

That was my first computer, I was 14 years old, my dad didnnt want a computer for games like commodore 64, it was really awesome, I spent hours to program with Basic

Friday 21st October 2011
Jerry Hubbell (Locust Grove, VA, USA)

I bought an MBC-555 in February 1984 I believe (when they were first released) and used it to learn programming. I actually developed the program "SolarSim" sold by MichTron and remember how neat it was that they decided to publish it and I still have the SoftSector magazine where the ad for SolarSim was placed. I still have my machine but it hasn''t been booted for over 10 years. If anyone has a copy of SolarSim, I would appreciate hearing from you as I lost my boxed copy I got from MichTron when it was first published.

Saturday 3rd September 2011
Alan W. (USA)

I have a 555 from my grandpa, who used Calcstar to keep track of stocks. Once in a while, I turn it on. It''s a lot more fun to write BASIC programs on actual hardware, not on some emulator. The computer turns 31 this year, and still runs flawlessly.

Thursday 1st September 2011
David Siebert

One minor correction, there was no MS-DOS version of Excel. The microsoft spreadsheet was called Multiplan. The store that I worked for carried one but I do not think it ever sold. People wanted PC compatibles and even if your computer was better than the IBM PC no one wanted it. Machines like the Z100 and the Tandy-2000 just sell. The 550 while inexpensive just wasn''t popular at our store.

Saturday 16th April 2011
Paul Smith (UK)

I ran a user group for the MBC55x back in the late 1980''s from my flat in Bath, UK. It was called "SMUF" for the Sanyo MBC User Forum, and I produced regular disk magazines for a while.... I still have some of them in my lock-up, buried amongst the other aging retro computer gear. I guess it taught me MSDOS and assembler pretty well, and I learned a lot - probably now all forgotten too! Great times....

Saturday 12th March 2011
Tim Buterbaugh (USA)

The MBC-550 (or 555) had a design flaw in its serial card. The company I worked for designed a replacement board which we sold to a company named Scottsdale Systems. They sold the improved systems under the name "Sanyo Silver Fox."

I remember that the test of IBM compatibility in those days was to run "Flight Simulator." I can''t remember if these machines passed that test or not . . .

Friday 23rd July 2010
James Prew (Albuquerque New Mexico, Usa)
Home-Web Designs

Wow. My First Computer, had the 555 2(360k floppy setup) and used to publish a newsletter with it back in 99. I still have the Dos 1.25 boot disk and WordStar, CalcStar, and ReportStar v3.0 and 4.0 software bundles. It''s amazing that anyone still remembers this.

Monday 25th August 2008
Joe Dellea

Among the quirks to the machine: the power supply was not a regular switching power supply. It was a transformer. Quiet machine. The keyborad lacked the "alt" key. There was a very handy reset button on the left edge of the keyboard. When you push the power button, you definately had the feeling that Sanyo had borrowed some parts from their stereo division!

Monday 25th August 2008
David Botkin (USA)

I owned & used an MBC-555-2 from 1984 until about 1992. It was the first MS-DOS compatible computer that retailed for under US$1000. It was also quite possibly the only (somewhat) IBM-compatible system that was actually SLOWER than an IBM PC (the PC clocked at 4.77 MHz, while the Sanyo clocked at 3.6, giving it a Norton SI rating of 0.8). The 55x motherbaord included a socket for an 8087 math coprocessor, which helped with spreadsheet applications.

Still, I loved that machine. While the mixed text-and-graphics video made it incompatible with many programs intended for the IBM (Lotus 1-2-3 being the benchmark at the time), WordStar worked just fine, as did Microsoft Excel (the original MS-DOS version) and also Borland's Turbo Pascal compiler. If your consideration was more for file interchangeability (it ran MS-DOS 2.1) than for software compatibility, the Sanyo was a solid, workhorse system at a very reasonable price.

Sunday 23rd December 2007
Richard N. ("Dick") Cote (Mt. Pleasant, SC)
Corinthian Books

Dear Friends: My Sanyo 550, purchased in 1984, was God's gift to a working writer. It came with WordStar, and I wrote seven books using the Sanyo and WordStar version 3.3. It was great fun -- really! -- learning DOS (not optional in 1984!), writing primitive DOS programs, and memorizing all those WordStar commands. My colleague and I, the Rev. George David Exoo, a Unitarian minister and an extraordinary writer, both knew that we would be toast if we didn't know a computer expert when we bought our first computers. And neither of us knew one or how to find one. So we both got identical Sanyo 550s with the same monitor and printer (total price, as I recall: about $1,500 for the package -- so that when something went screwy, we at least had each other to brainstorm with -- and that usually worked. For a writer, back in '84, getting a machine that would remember what you typed, let you change it anytime, and actually print it on paper was like having Christmas every day. And then -- lo and behold -- WordStar learned how to make footnotes that traveled with the text if you moved it! It still makes my heart beat faster when I remember the thrill of seeing THAT!

Now, 23 years later, I cringe every day knowing that one of my PCs is going to crash, lock up, or refuse to do what it did yesterday. My Sanyo never failed me, and after I gave it to a friend after four years, he used it for two more and then his friend used it another for two more. I'd love to have it back! I'd have it bronzed -- like baby shoes -- and use it as a pedestal to display the books I wrote "way back then." With warmest wishes -- Dick Cote' /

Sunday 24th July 2005
Blake Patterson (Alexandria, VA (USA))
Byte Cellar

Does anyone have a screenshot of the Sanyo version of the game from MichTron called Time Bandit? The Sanyo version took unique advantage of the Sanyo's higher # of on-screen colors vs. the PC of the day. Thanks.

Tuesday 3rd August 2004
Richard Yien (New York)

This was a good little machine... got it around 1983 and used it for WordStar, dBase, and BASIC programming. I remember buying it at Crazy Eddie or some place like it and thinking that it was a great deal for a PC compatible - then being disappointed after discovering that it wasn't really totally compatible. Had it hooked up to a Juki letter-quality printer...

Monday 19th May 2003
Omar Egan (El Salvador)

We used these machines for our business back in 1985... we later moved to more powerfull PC clones. I still have two of the machines in my attic, and recently cleaned them out only to find, to my amazement, that they still work! Does anyone know if there a users group alive anywhere? It would be great to find people who are still doing usefull things with these machines!

Wednesday 11th December 2002
Robert Lingenfelter (tx)

I had a 550 and learned alot about computers from it. Subscribed to the mag. I was able to learn some C programing (MIX C compiler), followed an article to get the speaker to play notes instead of that awful "honk!", and even soldered on extra ram chips to expand the memory to a whopping 512K! I kinda still wish I had it to play with. I wonder if anyone got MINIX to run on it?

Wednesday 10th April 2002
Tim Robert (Earth)

The reset button was near the top of the left side of the keyboard, to the left of the F1 key. When deep in thought about some programming issue, I often found myself idly fingering that button. I had to get out of that habit... My parents inherited my SBC-550 and used it well into the 1990s.

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