This classic, long-established PC has been looking down on PCMag's PC Labs for longer than anyone in our team can remember. For its big 40, we cleaned it up... and then took it apart.
If you want to make a movie about the 40th anniversary of the birth of the IBM PC (August 12, 2021), I will vote for a title: There will be dust. That's because my job is to improve the old IBM PCs in the PC lab of PCMag, so that they can be rejuvenated on important days. Ouch!
For decades, three IBM PCs from the 1980s, each equipped with a matching monitor, hosted PC Labs and stored them on high shelves. The works of the museum have survived actual use, multiple office relocations, and the screwdrivers of countless curious hardware analysts. They have been around for so long that no one on the 2021 team can remember when they were last demolished, dusted and marveled. In fact, no one is even sure which model they are.
I spent many days assembling and disassembling the PC, but I am not a product of the first generation of PCs. My first computer, around 1984, was a cheap Commodore VIC-20. On the black-and-white TV, I typed the BASIC programs in the magazine into it and saved them to the cumbersome cassette tape drive. (I have always envied those friends who have a more powerful C64 and its external floppy disk.) I was squandered for Apple Mac LC desktop in 1991, then Mac clone (Does anyone remember UMAX SuperMacs?), and then my number one PC clone...I never looked back.
That is to say: I missed the growing pains of the IBM PC in the first 10 years or so. Why not keep up with the lost time in 2021?
I took out the three IBM PCs of PC Labs from the storage. After about five minutes of Google search, search and stimulation, I found that two of the PCs were IBM PC XT, the second-generation model. (The little "XT" badge in front should be a dead gift.) They returned to the shelf. We will keep these two products for the 40th anniversary of PC XT in March 2023. But one of them is indeed the IBM PC Model 5150-the family name of the first IBM PC. (Hurray!) But it was half rubbish inside and out. (Shh!)
In the distant past, PC Labs may have held a rave party in its relic Model 5150 on the occasion of the 20th or 25th anniversary of the IBM PC. One of the floppy drives has been removed and placed aside, it may not be the original. Some smart people inserted an HD-DVD drive in half of the double-height 5.25-inch drive bay. (Remember HD-DVD? You probably shouldn't do this.) The other half has an old, dirty 5.25-inch Seagate hard drive sitting inside, sliding loosely.
Remove the lid, the inside of the 5150 is like the aftermath of a fraternity party. The brown slime has taken a place on some ribbon cables... somehow it is still sticky. Coca-Cola leaked? (Considering age, maybe it's New Coke.) Battery acid? No matter what it is, alcohol wipes can solve it. (Um.)
Loose shell: the interface card of the Seagate hard drive. Literally means loose-like loose change. Take that out. It's not a good sign either.
We only have one IBM PC Model 5150 that is well used and often abused. The company barcode from Ziff-Davis (PCMag's parent company for many years) indicates that this was once an IT property, the main force of some long-time editing. Some prescient PCMagger has saved it from the scrap pile for future use.
Some reconnaissance was carried out around the motherboard, and this tidbit was found along one edge: "64KB-256KB CPU." This indicated that the 5150 model was a later revision. Alas, our IBM PC is not the "original" original, the OG 1981 PC. It was assembled a few years later.
Best guess: 1984. The fabric label affixed to the inside of the mono speaker indicates that the speaker was manufactured or assembled in September 1984, possibly in Florida. It is not clear which label is.
The problem is that the "original" IBM PC that debuted in 1981 was called the Model 5150, but the 5150 was subsequently revised. It was in production for most of the 1980s, adjusted and improved, and sold in parallel with later models, such as the next major version, IBM PC XT. Our laboratory survivor is not a primitive man, but it has the same exterior and the same guts.
We don't have an IBM keyboard at hand, and DOS floppy disks have been lost for many years, so we can actually do very limited things with PCs. Connecting it to a monitor (more on that later) and starting it will only cause a series of angry beeps. But we wanted to film the system to supplement PCMag's republishing of the original review of the IBM PC in 1981. You can view it in the link and browse the original magazine on Google Books (not to mention our back question).
So in the process of photography, I did what any self-respecting hardware hound would do: tear it down! Our patient staff photographer Molly Flores (Molly Flores) stood by to take pictures. We performed the 2021 PCMag studio processing on PCs in the mid-1980s. It seems a pity to waste all these cute images, so come and visit with us.
Again, I am not a child of the original PC revolution in the mid-80s, so my analysis here will be a little dazzling, and will follow the wonderful memories of former editor-in-chief Michael Miller in some places, he reported first-hand . Therefore, please treat me correctly and leave your memories in the comments at the bottom of the article!
First are some fascinating photos of the old 5150. Molly makes it look more beautiful than it looks. I use some mild soap and towels to scrub the chassis, add alcohol wipes to remove stubborn dirt, and use canned air to clean the dusty rabbits inside. She scrubbed the rest in Photoshop.
That is the IBM 5151 monitor on the top of the case. This is an absolutely monochrome CRT with excellent native resolution...80 characters, 25 lines. (Please note that these are characters, not pixels.) IBM's Monochrome Display Adapter (MDA), an early video card, could have powered the panel, although we were surprised when we opened the case. (It will be described in detail later.)
...There are no other controls on the display, not even an on/off switch. That's because the monitor plugs directly into the back of the PC case through two hard-wired cables...
...One for the power supply and one for the video signal. (We will cover these cards, ports, and sockets later.) Powering the PC desktop will also power the monitor.
So here we have a 5150-type outer chassis, which is cleaner than since around 1986...
The first two drives are 5.25 inch floppy disks with locking levers that engage with a satisfactory ka-chunk. We will introduce them in detail later; we will pull them out. (Indeed, I had to put these photos back in place; the museum’s old collection was replaced decades ago.)
This is a review of the entire rear panel. There are three cards in the ISA expansion card slot, and the unused slot lacks a cover, which has been a long time since.
You can also see the old "Made in USA" indication above the model identification badge. How many desktops can you say so now?
Then there are hard-wired ports for IBM peripherals. Obviously, the cartridge port is not widely used, because most versions of the 5150 sold include a floppy drive. (Any mention of tape connected to a PC will make me shudder: Thinking back to my VIC-20, my career began with early types of PC storage, most of which came from tape drives like Exabyte, Iomega, and Tandberg in the 1990s. .)
The main power switch is located on the right side panel, near the back. It is accompanied by a beautiful, fleshy click. You won't get such an authority switch on your desktop anymore, that's for sure. Maybe it's a fighter console.
As for the remaining ports of the PC, they are located on the backplanes of several expansion cards. The one with the RCA jack on the left is obviously a graphics card; a 5151-type monitor engages with a 9-pin connector. But what is on the right?
I'm old enough to remember SCSI cards and parallel ports, and it looks like the latter. There is only one way to find out. (In order to find out that I was wrong, that's it.)
One thing needs to be clear: everything about the original IBM PC is heavy. IBM's giant mainframe was once known by the nickname "Big Iron", but this desktop computer fits the status of "Little Iron" (although yes, the case is actually steel). It is dense and heavy.
The cover is especially true. Slide it forward to remove; don't put it on your feet. I left this dazzling naked frame...
...Except for the large and delicate circuitry of the dual floppy drive, it doesn't look so unfamiliar compared to today's desktop systems.
Indeed, with the power supply, the label on the top is more worn out, but the layout is familiar, and there is even a main power connector and...Molex connector to the motherboard! These are still in use today.
I want to go deep into the motherboard, so some components have to be moved. Pull out the expansion card first, and press it on the back panel with screws.
This is the first one, and it is connected to a floppy drive via a ribbon cable. That is a floppy drive controller card. At that time, many basic system connections had to be added through expansion cards...
You can see that the internal ribbon cable is still connected; it is daisy-chained to two 5.25-inch floppy disks. Further research shows that this card is an updated version of the controller card. The external port is for external floppy drives; it is not a SCSI or parallel port.
This huge graphics card is as long as modern high-end graphics cards, and more than half of them are fixed with daughter boards. The source of this card is a bit mysterious and requires some homework. This is not IBM's basic MDA card. At first I thought it might be an after-sales upgrade. However, this is a problem of IBM. The IBM Enhanced Graphics Adapter (EGA), the daughter board is an extension of the graphics memory, and is installed face to face with the card. (The card has a 64K graphics memory standard.) The predecessor of VGA, can be used for color output up to 640 x 350. luxury!
By modern standards, this card is definitely an unusual beast. There is a layer of transparent thin plastic on the back of the daughter card to prevent the extra thickness from contacting the adjacent ISA card and possibly causing a short circuit. The red block ("Grayhill") in the upper right corner is a set of DIP switches for configuring the operation of the card according to the monitor you are using. (We will see more of these things later.)
That is a lot of chips and solder joints. As far as I know, it is one of Intel's so-called "onboard" ISA memory expansion cards. This is how you expand the main system memory, long before PC standard DIMMs and SO-DIMMs appeared in anyone's eyes.
This is a very international board. If you look closely, many chips (the NEC memory module pandemic) are made in Japan, but some others are made in Malaysia, Mexico, and El Salvador. Others who do not have a clear citizenship may also be made in the United States. It is not so much an ISA card as a United Nations summit.
So this brings us back to the motherboard. But to remove the circuit board you need to remove one of the floppy drives, which prevents access to one of the screws that secure it to the chassis. Therefore, remove the ribbon cable and disconnect the power connector of the leftmost drive...
Then, take out the screwdriver, unscrew the two screws, and the drive comes out of the case just like any good 5.25-inch device before...
This is the familiar Molex connector that powers the drive; some peripherals are still used in personal computers today...
So, that key screw is exposed on the motherboard! The few screws in the corners (normal heads instead of Philips heads, which is a surprise) are easy to remove. But the motherboard is also held in place by some slightly evil plastic extrusion connecting posts, which pass through holes in the motherboard. You must gently squeeze them with your fingers or pliers, and then pass them through the mounting holes of the circuit board. The problem is that you free some, and then they reappear when you work on the rest. You need six or seven hands to squeeze them at once!
However, a patient released them all in about 10 minutes, and the motherboard slipped out from the side of the case...
What a spectacular sight! Not a stranger. Although there are some obvious differences, this is not a million miles away from modern motherboards. On the one hand, this is the entire I/O port panel...
Now, these early PC motherboards do not have the BIOS as we know it. You configured your hardware with DIP switches and used it with the manual (there may be some desperate calls to technical support or your geek partner)...
I recalled this from some later PC clones I owned. (I still remember that I hated them.) There are two batches of these light blue bad guys on the 5150 board.
Also on board: more memory. It's already welded here. We have moved away from the ubiquitous DIMM era. The memory density has not yet reached the level they need to get enough memory on a memory stick of this size...not even close.
This is the main power connector of the motherboard. Before yanking the motherboard, I disconnected the main lead of the power supply. It is a foreign object to the standard ATX 20+4 pin connector as we know it today, but it is an obvious ancestor.
Compared with any recent motherboard, one thing that is obviously missing is: Where are the CPU, CPU socket, and heat sink? Well, this requires some reconnaissance, but we finally found the chip...
Post time: Dec-10-2021