Thursday, March 15, 2018

The Amstrad ALT-286 - Repairs, FDD Not Working, Battery Damage

The Amstrad ALT-286 is a very nice machine, its a mix between the TOSHIBA T3100/20 and the SHARP PC-4500.

It shares same technology like the two mentioned above but the display its superior due to the fact it came on the market almost 3 years after the Toshiba and Sharp. Even if it was more budget oriented the computer has a lot of features and the quality build is impressive.

I got this computer from a local sales site and the computer was stated as working. The amount requested was 699 LEI, that means in EUR 155. I called the seller and he was OK to sell it for 40 EUR. The original post:

Short technical description:
Computer: ALT 286
Processor: 80286
Screen: VGA LCD 640*480 Pixel
Reverse by programming plus contrast and brightness switches
Graphics: Cirrus Logic
Memory: 4x 1024 KB Max
Harddisk: 20 to 60 MB
FDD Drive 720 KB FD-235HF
Extensionslots VGA
AT Keyboard
FDD Floppydrive
System: DOS 3.3 and DOS 5.0
Printerport Centronics
Serial Ports 2x9 Pens. One for mouse
Weight: 7 KG


The Computer had better days, the HDD spins up but OS is not found, and the FDD is not working for sure as it has a very unlikely sound when booting and it does not spin the floppy disk. I will take apart the computer these days and I will replace the HDD and the FDD unit. The FDD unit can be replaced but there is a custom mod you have to do on the Floppy cable. I found an interesting article of someone that replaced the original unit with a standard one. I will start working and get back to you with the details.

Step 1 Disasembly

Remove the screws from the bottom \ back and aside.

Bottom view

Step 2 Remove top cover

To do this you need to have your screen in OPEN position and then just lift the top cover from the bottom and put the cover on a side like in the photo. The display cables are pretty long so you can leave it like that or remove the cables to fully take apart.

Inside #1

Step 3 Remove stuff


For this you need to remove the 4 screws in the picture and just lift up the socket on the right top of the module. (this is not mandatory but you need space to remove the FDD)

Extension module\ Bios chip (on the back)
View on RAM and BIOS (the sticker came off, don`t get it into the light as its UV sensitive and it will erase data\I had put a black sticker on that)


Remove the 5 screws and lift up the FDD unit. 

Floppy Disk Removed


Next part is to remove the aluminium cover (note that this cover has also the role to spread the heat of the chips)

Battery leaked on the MOBO :(

Even if the battery looks in sharp condition you have to remove it. If it hasn`t leaked it will so just replace it or cut it off. I just removed it cause I use this computer rarely so I just don`t care the setup will forget the HDD config or the clock...


Next part is to remove the metal frame like in the picture below:

Metal Frame


Battery damage on mobo
I had used some Isoprylic Alcohol to clean the damage and vinegar ti neutralize the acid area.

Now this looks better! Lets get some soldering done!
Nice and Clean
The capacitor seems fine, so I just resoldered but its legs were damaged so I used some extra wire... a lot of extra wire :)

You have to agree it looks artistic...  ;))) be careful on the polarity (the capacitor has a black mark for negative)

Now lets get back to the FLOPPY part 

Basically you need a standard 3.5 FDD, I got one with the DS jumper so for me its very easy to make the mod. Basically I just have to remove 5 7 9 11 wires stated in above diagram and get the +5V on the new FDD unit.


Cut 10 and 12 and reverse 10-12   \ 12-10

OLD VS NEW Floppy design

I was able to change the plastic front ornament from one to another, they are both made by TEAC company.
New FDD with the old grey front ornament
I think the picture above is very descriptive and for those who are technical people will manage easy.
Where my hand is is the connector that fits the mobo.

1 is the green wire \ use 11 for +5V and cut down 5, 7, 9, 11

I had put some isolating tape just to make sure the wires won`t touch something inside the computer.

Use any tape you have and place on both sides

Now Place the red wire on the +5V connector on your new Floppy Disk.
+5V on first inner pin


Now place the FDD cable and the pin on +5V and boot up your PC!

MS-DOS 5.0 is now loaded!

NEXT STEP - Sit back and enjoy your vintage laptop!

If you have any questions, leave a comment.
Don`t forget to check out my museum`s Facebook Page and WebSite

Thursday, October 5, 2017

Macintosh Classic boot from ROM

The Classic is a unique machine, its the ONLY Mac that can boot an OS from ROM, Hold down command-option-x-o on bootup and it will start System 6.0.3 from the system ROM.

Wednesday, January 11, 2017

Sharp PC-4500

Sharp PC-4500 (4502)  

Restoring History

Manufacturer: Sharp Corporation (Osaka, Japan)
Release date: October 1987
Reference: PC-4500
Processor: Nec V40 at 7.16 MHz or equivalent (compatible with i80188)
Memory: 256 KB or 640 KB RAM expandable to 1.6 MB Including 1 MB of EMS memory
Display: CGA compatible monochrome LCD display (Backlit on models 4502 and 4521)
Storage: 1 or 2 floppy drives 3 "1/2 of 720 KB
Original Add
Or 20 MB hard drive according to models.
Interfaces: Parallel
1200 baud modem and optional external CGA
Software: Ms-Dos 3.2 Sharp

Particularity: Announced at Comdex Spring 1987 and marketed from October of the same year, this entry-level PC compatible PC is sold at a rather competitive price. The compatibility is good but the performances are not extraordinary. Note that it requires a version of Ms-Dos of origin Sharp to start.

3 versions ever existed:

PC-4501, 256 KB with 1 drive, LCD not backlit
PC-4502, 256 or 640 KB with 2 drives
PC-4521, 640 KB with 20 MB hard drive

My machine is a PC-4502, 2 Floppy disks, no HDD, back-lit display.

I got this machine 2 weeks back of the internet from a guy who said that it does not know if the machine is in working condition.

I am not very happy that I did not make any pictures how the machine looked when I got it but I can rate it a 5 out of 10.... and I will show you why.


1) The DC IN connector and wiring is missing.
2) The DC POWER BUTTON is missing.
3) The Floppy drives power connectors are missing. Power cables from the Power Supply to the motherboard are damaged and a few blown capacitors.
4) Missing bolts and screws
5) Cracked case
6) No AC Adapter

1) The DC IN connector and wiring is missing

This unit was completely butchered by someone who has no idea how electronics work. It seems the unit had some problems booting so someone just messed with the cables.

I had to rebuild the whole POWER CONNECTOR SOCKET!

Parts Used: DC Connector (from an old Toshiba notebook), piece of black thin plastic, soldering gun, poxipol-plastic welding, superglue and a LEGO piece :)

I started by cutting a square piece of plastic with a hole inside, same plastic as a credit card and fitting it into the unit with a drop of super glue, just so it would hold on when I will apply the other stuff. I needed this in order to mask the DC connector so when the unit will be assembled it will look like the original does.

Thin plastic square with a hole for the DC IN Connector
I needed to find a way to mount the DC connector a little higher so it will perfectly fit like on the plastic squares hole. 

So I found a permanent fix: LEGO! 

Bringing the base at the right size so the DC connector will perfectly fit the hole

I had soldered the + and - wires on the DC connector. THE SYSTEM BY FACTORY HAS THE CENTER PIN AS NEGATIVE. As I have a more modern Power Adapter I will use the center pin as + . 

DC Connector - Not Original one
Again I used plastic welding and fitted the connector on the LEGO piece.


2) The DC POWER BUTTON is missing

This unit has no power button so I googled but I can`t find much on this units insides to see what power button it originally had!!!

Lucky me I found this YouTube video of the inside of a PC-4521 machine....

So as you can see on the video the Power Button is similar with what you will find in an old laser pointer. And ...I still have some laser pointers in a shoe box in my storage.
I had cut the laser board with the some of the board around in order to fix the button on the original surface.

And this is the Output of 20 minutes of hard work :)

3) The Floppy drives power connectors are missing. Power cables from the Power Supply to the motherboard are damaged and a few blown capacitors

Looks like the one of the previous owner had tried to "repair the unit" by cutting half of the wires in order to power the motherboard from another power supply. I had spent some time figuring out what happened so here`s what repairs and fixes I had done:

Replaced marked in RED capacitors. It seems the power supply did not start because of those.
New wiring for the Floppy Disk units.
New wiring for the Floppy Disk units.




1 out of 2  Drives are only present. Date is 10 of September 1987

The weird thing is that the Keyboard is PASSED as test but no keyboard is attached at this moment...

There are some jumpers on this machine and I found some info on some forums... I really hope I can get the second FDD working so I can put MS-DOS 3.2 on 1 drive and some CGA apps on the other :)

I got the Jumper settings for SHARP PC-4500 and 4502 from a forum:

Link here.

"Here are the settings my PC4500 came with on the DIP switch bank on the bottom of the unit:

3 ON
5 ON

I would guess that one of these switches defines the presence of the second floppy drive and perhaps the presence of a full 640K memory card (I have both in this machine)."

The settings above suggest 640k memory and 2 FDD installed.





This restoration of the SHARP 4500 was a true success! :)

Thursday, December 8, 2016

The world did not begin with the World Wide Web

The world did not begin with the World Wide Web
                                                                                   by Bogdan Tirziu

     The Internet is the biggest and the most advanced technology of this century. Its basically a huge amount of information and knowledge that opens up unlimited possibilities and opportunities to the masses.

     Today it is the biggest source of information to mankind. Learning and getting knowledge on thousands of topics has become an easy task. It just requires typing a single word on a search engine and retrieves thousands of search results that are close enough to your query. Internet has made the information just a click away. While you read this, routers, servers, converters etc. work for you to receive and send data. For the younger generations this seems normal and it seems that the world was like this for a long time.

    "The History of the Internet is begins with the development of electronic computers in the 1950s. Initial concepts of packet networking originated in several computer science laboratories in the United States, United Kingdom, and France.[1] The US Department of Defense awarded contracts as early as the 1960s for packet network systems, including the development of the ARPANET. The first message was sent over the ARPANET from computer science Professor Leonard Kleinrock's laboratory at University of California, Los Angeles (UCLA) to the second network node at Stanford Research Institute (SRI). Commercial Internet service providers (ISPs) began to emerge in the very late 1980s. The ARPANET was decommissioned in 1990. Limited private connections to parts of the Internet by officially commercial entities emerged in several American cities by late 1989 and 1990,[5] and the NSFNET was decommissioned in 1995, removing the last restrictions on the use of the Internet to carry commercial traffic."
                                                                                                                               source: Wikipedia

     So the Internet is about 30 years old and has been in a continuous change ever since. For example this is how the internet looked back in 1994. Information was growing, technology was growing, so this pages might seem primitive, back in 94` these were super sharp and fancy. You can compare with the 3rd image where you can see how the internet was introduced to people in the first place.

                           One of the first web pages

As stated in the title "The world did not begin with the World Wide Web", back in the late 60`s some Universities had a sort of communication between computers but that was not intended for the masses and it was more an experimental thing as the protocols of communication used were not yet a standard so everything was happening local.

Everything was about to change

Many years ago, long before the birth of the web, there was a time when France was the happening-est place in the digital universe.

"What the TGV means to train travel, the Pompidou Centre to art, and the Ariane project to rocketry, in the early 1980s the Minitel was to the world of telecommunications."

The Minitel was a Videotex online service accessible through telephone lines, and is considered one of the world's most successful pre-World Wide Web online services. Basically the French Telecommunication networks brought a FREE boxy thing to every home and presented the users the benefits. In 1982 almost every french person could access some awesome services for that time, users could make online purchases, make train reservations, check stock prices, search the telephone directory, have a mail box, and chat in a similar way to that now made possible by the Internet.
From 1982 to 2012 it was used by 25 million people (of a total population of 60 million). Developed by 10,000 companies, in 1996, almost 26,000 different services were available. Even with the expansion of the internet in France this service was available and used by 9 million until 2012!

The "boxy" thing

"Minitel used terminals consisting of a text-based screen, keyboard and modem. Simple graphics could be displayed using a set of predefined graphical characters. Aftermarket printers were available.[9]

When connecting, the Minitel integrated modem generally dialed a special number connecting to a PAVI (Point d'Accès VIdéotexte, "videotext access point"). The PAVI transmitted information to the servers of the appropriate company or administration using the Transpac X.25 network.
In February 2009, France Telecom indicated the Minitel network still had 10 million monthly connections. France Telecom retired the service on 30 June 2012."
source Wikipedia

Thanks to this weird monitor attached to the telephone, while the rest of us were queuing for tickets at the station, the French were already shopping and travelling "online". A small screen with a keyboard, the Minitel was a very basic computer that allowed users to access text-based data over phone lines. Other countries looked on this with admiration, and the French were proud. (proud nation anyway)...

As President Jacques Chirac said: "Today a baker in Aubervilliers knows perfectly how to check his bank account on the Minitel. Can the same be said of the baker in New York?"
Students were logging in to check exams and to subscribe to different activities, small business had all accounts linked with it and could see the balance real time. It was for sure a limited "Internet connection" but it was something mindblowing taht you could chat with your brother that is 3 county's away. The incomes of Minitel were tremendous, they were making more than 1 million $ per day as the most expensive service was 1 EURO in today's money. The most expensive and used service was... PORN. Yes... the french had dozens of notorious "pink" services. They usually employ a woman's name or baldly suggestive titles such as "Brutal Beach," "Perver" and "Cruella." Advertised on lurid posters and billboards all over France, the services offer a whole menu of options for the user, ranging from explicit sexual graphics to direct dialogue with another person.

Soon, Belgium, Brazil, Canada, Italy, Germany, Finland, UK, Sweden, Spain etc. had tried to adopt the system, but the Internet was already available so the war was lost.

I know it looks terribly old-fashioned by today's standards, but it was simple to use, you pressed a button and it did something, just like on a tablet today.

"The failure of Minitel was not one of technology," says Benjamin Bayart, head of France's oldest internet provider, French Data Network.
A recent Minitel set
Image captionThe design of the Minitel changed over time
"It was the whole model that was doomed. Basically to set up a service on Minitel, you had to ask permission from France Telecom. You had to go to the old guys who ran the system, and who knew absolutely nothing about innovation.
"It meant that nothing new could ever happen. Basically, Minitel innovated from 1978 to 1982, and then it stopped," he says.

As an old hardware collector, I really want to get my hands on one of this terminal computers. I think of them as an important part of the History of the Internet.