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IBM 5150 (Alice) Specs


Veteran Member
Feb 21, 2011
Eugene, OR
IBM 5150 PC System - AKA "Alice"

Thomas's IBM’s 5150 PC is was introduced in 1981, although “Alice” is a 3rd revision, with 256Kb of memory on the mother board, among other things. It is also one of the many different models everyone associates with having dual 5-1/4” floppy drives. The complete list of hardware components that make up the entire system is included below, as well as which piece of hardware is installed into the individual cases.

My particular IBM PC is model 5150-184 with a serial number of 1,395,232. By itself, the PC is nothing really special other than that its overall condition is almost like new! There are no signs of use, other than a marker “scratch” on one of the keyboards keys. The marker tick was removed with rubbing alcohol on a cotton ball. Now, even the keyboard is in “Like New” condition.

Based on information located on the tag attached to the internal PC speaker mount, my 5150 computer system was manufactured in August of 1984. The expansion unit I managed to acquire does not have any real documentation other than what is included in the IBM PC Options and Adapters manual, and there really isn't much else. There is no real way of telling if the paper work included with the expansion chassis is that which belonged to the original unit. However, during an email discussion I had with IBM personnel, I was sent the Press Release announcing the IBM 5161 Expansion Unit to the public in 1983. A copy of the original press release has been posted to www.minuszerodegrees.net. You can read it by clicking on the link towards the bottom of the page here: http://www.minuszerodegrees.net/5161/doco/5161_documentation.htm.

The IBM 5150 PC was designed with only five ISA expansion slots. However, by utilizing an expansion chassis, I.E. the IBM 5161 for the IBM 5150 PC and IBM 5162 for the IBM 5160 XT, which offers 8 expansion slots, the system now has 11 expansion slots available, or 11 when the expansion unit is attached to an IBM 5160 PC/XT. One port on the host computer, and one on the expansion chassis must be occupied by the extender, and receiver cards. These two cards link the host computer and expansion unit together. Also note: In my case, I chose to install the extender and receiver cards into the very last expansion slot, or to be more precise; the furthest expansion slot from the power supply. On the 5150 PC, that will be slot 5. However, the receiver card cannot be installed into a 5160's last slot, or slot 8, because of differences in the expansion of the XT. Slot 8 was configured differently for future expansion options; which won’t be covered in this document.

Here is a complete list of components that make up the entire IBM 5150 PC I call "Alice" including the IBM 5161 expansion chassis, and all internal and/or external peripherals.

IBM 5150 - PC

1. IBM 5150 Personal Computer revision 3, Mother Board 256Kb of memory installed.
a. Intel 8088 Processor running at 4 MHz
b. 8087 Math Co-Processor
c. 256Kb onboard RAM
2. Original floppy drive controller card.
3. 2 - Tandom TM 100-1A - 360K 5.25" Full Height Floppy Drives..
4. Original IBM CGA 16 color video adapter with integrated parallel port (Combination card) (LPT1)
5. Original AT style 83 key keyboard with mechanical/electronic inductance (capacitive) key switches
6. AST Six-Pack Plus card with the following options installed and enabled:
A. Asynchronous communications (serial) port,
B: Parallel Port, *
C: Game Port, *
D: Clock and
E: Calendar
F: 384 Kb memory upgrade (Bringing the system to its full 640 Kb of RAM.)
7. IBM 5161 expansion unit extender card (sometimes called a transmitter card.) (Installed into slot number 5 for installation simplicity.)**
8. Microsoft “Green Eyed” serial mouse

The IBM 5161 expansion unit is connected to the AST (Installed into slot 5 in the IBM 5150) expansion via ribbon cable running to a separate expansion slot cover; which means the AST Six-Pack Plus card requires 2 expansion slots in order to allow full functionality. This setup also makes using all 5 internal ISA expansion slots virtually impossible, unless the AST’s cable is run through a gap at the top of the assembled case. This is not recommended as the AST’s ribbon is easily damaged.

** If using the IBM 5161 expansion unit with an IBM 5160 computer, or equivalent, the expansion unit’s receiver card MUST NOT be installed into slot 8 (the expansion slot furthest from the power supply) because this particular slot is configured differently and is used for specialty add on cards.

IBM 5161 - Expansion Unit (Chassis)

1. Western Digital MFM hard disk drive controller***
2. 2 - Full Height Control Data Systems 30 MB hard disc drives, MFM formatted.
3. Intel Ethernet 8/16 LAN adapter
4. 3Com 9600-baud modem
5. Dual DB9 serial port card (adding 2 separate 9 pin serial ports to the system)
6. IBM 5161 Receiver card. (Installed into slot 8)

***The Western Digital MFM hard disc controller uses its own BIOS which can make set up easier. But, this same BIOS, if not set up properly, can be very difficult to reprogram, so taking the extra time to verify each and every connection method, dip switch setting etc. is time well spent.

Power Management:

IBM’s choice of locating the power switch all the way to the rear of the computer’s case on the right side, was and still is, not very comfortable for users who are left handed, or like me, who’s right arm will not allow them to easily reach the power switch on the PC. Add in a situation where one also has an expansion chassis installed, the simple act of booting up the system can become an exercise in contortionism. The user must reach over and twist in such a way, that falling out of the chair is a great possibility. This particular IBM 5150 PC system has the expansion chassis placed on the bottom shelf of a compact portable work station. So you can imagine having to reach over and around to the rear of the entire desk just to apply power to the expansion chassis. Then the user must have to do the same thing, although not to the same extent, to boot the PC. Add in the fact that each component and peripheral has their own design quirks and it is plain to see that something much simpler was required.

As you can imagine; powering up the system is not that comfortable for left handed people, or those with limited use of their right hand/arm, as is my case, especially from a wheelchair without some sort of centralized switching station. Simplicity was the primary reason many people in the early days of the PC purchased power management systems such as the DataGuard5000 described below. Most power management systems also offered some sort of protection from power spikes in the form of surge protector circuitry.

DataGard SLWaber Computer Power Center and Surge Protector.

The DataGard 5000 unit sits between the main PC and the monitor. It contains a set of 5 switches to control various computer components. I have chosen a configuration which is the most comfortable to me, and also more logical than other setup choices available. Of course, you may wish to use another setup option. That is another reason I chose the DataGard 5000; simplicity, and usability. After trying numerous setup options, I chose to utilize the following:

1. Master - Expansion Chassis.
2. Aux 1 –Cassette recorder.
3. Aux 2 –3.5” Back-Pack Drive (Allows the use of 3.5” 1.44 Meg floppy disks, connected via LPT Port)
4. Printer – IBM 5152 Graphics Printer (Dot Matrix)
5. Monitor – PC and monitor

Computer General Operation

Normal operation of an IBM PC, and the majority of its clones meant that, in order to boot the computer, all that was required was to turn on the power supply. However with this particular configuration which includes the IBM 5161 expansion unit; to boot the system properly one must first turn on the expansion chassis. Give the expansion units hard discs approximately 15 to 20 seconds before booting the main PC. This will give the hard disk drives the time required to “spin-up” to operating speed, prior to the system attempting to load the OS.

In this current setup and configuration, the “Master” switch on the DataGard controls power to the IBM 5161 Expansion Unit. The switch labeled “Monitor” controls the main PC. It is very important to remember that when using power management devices like the DataGard 5000, that all of the devices plugged into it must have their power switches set to, and left in the “On” position. Otherwise, when you apply power for that device, nothing will happen. On the DataGard Power Management system, you can easily tell which components have power, and which do not, simply by looking at the front panel. Any switch with a green LED lit up signifies that power is on for the particular device. One other item to note regarding power management: If the “Master” switch is not in the “ON” position, no other device can be powered on. The master power must be turned on before any of the other switches can supply power to their respective devices.

Modern computer systems do not use this type of internal or external power management. Indeed, when you turn off your home PC, there is still some current draw to keep the computer’s clock and calendar functions active, but in the early days of home computing, and especially for early IBM PC’s; turning off the power switch cuts all power to the system.
Boot Process

In order to boot this system properly:

1. Depress the “Master” power switch on the front panel of the DataGard 5000.
2. Wait 15 to 20 seconds (I have found that by this 20 seconds, the “Boot up” process is more stable and start up errors are virtually eliminated) **
3. Press the switch labeled “Monitor” to power on the main PC. Let it go through its own boot procedure: Typically, up to 1 minute, depending on how much memory is installed in the system.
4. Once power is applied to the PC, any of the other component switches may be pressed to apply power to any other devices attached to the computer and the power management unit; such as monitor, printer, tape recorder power supply, external cassette drives, etc.
5. Since this system also includes an IBM 5152 Graphics printer; which is a Dot Matrix printer, it is connected so that depressing the switch labeled “Printer will turn it on.
6. The very 1st switch from the left is labeled “Aux1”. This switch I reserved for the Cassette Tape Recorder/players power supply for loading and saving any programs written in BASIC.
7. The next switch; AUX2, is reserved for a MicroSolutions Back-Pack 3.5 floppy drive, connected to the PC’s LPT2 port.

**Note: If insufficient time has elapsed between applying power to the expansion unit and booting the main PC, or if the PC is booted prior to powering on the expansion unit, one of two errors will result. Error 1701 will display on the computers’ monitor as a boot failure if the expansion unit is not powered on prior to the PC. This situation cannot occur with my setup. If the Master switch is not in the “ON” position, none of the other switches can power on. Error 1801 will display if the expansion chassis is not connected. In either case, the boot up process will fail and the system will be completely unusable. One thing to note here too is that in the event of a computer malfunction, or error situation that causes the need to reboot the PC; there is no need to power down the expansion unit. In this current configuration; simply turn off power to the PC by pressing the “Monitor” power switch, and the PC will power down. Wait approximately 20 to 30 seconds for the error condition to clear from the system memory and press the “Monitor” switch again to re-boot the computer. None of the other peripherals need to be powered down because of the method in which the first IBM Personal Computers operated. This makes power management very simple.

Miscellaneous Information

The desk used here was actually a laptop desk which was purchased previously, and used as a laptop station a few years ago. The desk served its purpose, but because another much larger desk was purchased to work as not only a computer desk, but all around office unit. So this little work station was no longer needed, nor required. Indeed, the desk was going to be sold once the larger desk was put into service. However while unboxing the IBM PC, my wife immediately thought this desk would be perfect for the IBM 5150 configuration. There were some slight modifications that needed to be made, such as replacing the original casters with much heavier duty ones. This made moving the desk, even on carpet, much easier.

Keep in mind, this was well before acquiring the IBM 5161 expansion unit. But even after adding it, the desk still fit its purpose perfectly. Adding a small stand to allow the printer and a decent amount of paper completed the setup. This little laptop station has become a natural addition to the overall setup.

Notice the location of the expansion unit on the bottom shelf? When the expansion unit was located, and finally purchased, several methods of setting it up with the overall system were attempted. One method consisted of stacking the PC and expansion unit one atop the other. It really did look great! However the viewing angle was terrible. And the angle between the monitor and keyboard was equally atrocious! After only a few minutes of looking upward at the display, I could feel the onset of a headache. The viewing angle was just too high. So, the expansion unit was relocated to the bottom shelf of the desk. However; that brought on another problem: accessing the power switch to turn the unit on. Another solution had to be found.

And here is where the desks design really came in to play. By placing the expansion unit on the bottom shelf, instead of stacking the PC and expansion as most people would probably have done; the very odd head angle was completely eliminated. Adding the expansion unit to the top of the desk added an additional 5 ½ inches to the overall height of the system. Not only does that raise the monitor to an uncomfortable viewing position, but by placing the expansion unit on top of this portable desk, almost all of the entire weight would be on top. That in turn would make moving the system much more dangerous and prone to tipping. By splitting the weight almost equally between the upper and lower levels on the desk, the center of gravity was effectively lowered quite nicely. Since the expansion unit weighs approximately the same as the main PC, and knowing that the PC houses the floppy disk drives which would be accessed far more than anything in or on the expansion chassis; it made perfect sense to leave the PC where it was at the top, where the floppy drives could be accessed easily. One major drawback however, is IBM’s choice of locating the power switch on the very right rear corner of not only the expansion chassis, but the PC as well. And, while the printer has its power switch located on the top of its case, it is still somewhat awkward to access being so low. However, the DataGard 5000 takes care of power for the printer as well. Now, to power up the entire system, all that’s needed is to press a few switches on the DataGard 5000.

The DataGard unit also acts as a surge protector, and I’m sure that has saved my system from some recently occurring spikes in the power that is fed to the home.

Microsoft “Green Eyed” mouse:

In 1982 Microsoft launched its computer hardware division by developing a mouse. Its Microsoft Mouse was introduced the next year accompanied by a text editing software and an instruction tutorial. The mouse was dubbed the “green eyed” mouse because of its two green buttons which give the mouse the appearance of having cartoon green eyes.

The Microsoft Mouse required an IBM personal computer with 64 K of RAM. It initially required a bus interface card to install in the computer, and came with a manual and a software diskette. Later you could get a bus or a serial connector, like the DE-9 pin and/or a DB-25 serial port. The bus mouse connected to the Microsoft bus card installed in the computer. A Japanese company, Alps, manufactured the mouse for Microsoft. Like newer roller ball mice, the Microsoft Mouse used a heavy steel ball set towards the back of the mouse mechanically tracks the position by rollers for the X and Y coordinates. The key difference being that the ball used in the “Green-Eyed” mouse was naked steel and not covered with rubber. To digitize the position for the computer to read, the mouse connected to a mouse card installed in a slot in the computer. To clean the ball a screw released the retainer ring. Now however, since the mouse uses a standard 9-pin serial port to connect to the PC, there is no need for the original serial bus card that accompanied this, Microsoft’s first release into the hardware market.

Although the mouse is small it is quite heavy. To its credit, its shape curves a bit unlike other completely blocky early mice. The Microsoft brand is so delicately inscribed on the left at the wrist edge of the mouse that it's nearly invisible.
The mouse and 9 pin serial bus card sold for $195. Bill Gates said, in an interview with the Smithsonian, "When we first brought this out we ordered 50,000 and it took over a year to sell the first 50,000." Today, these mice can be found on E-Bay selling for as much as $500.00, for the mouse alone! And sales are typically very fast, often times selling at the buy-it-now price listed by the seller well before the end of the auction.

More on the IBM 5161 Expansion Unit

Before buying my first IBM 5150 computer system I came upon an article describing the existence of something I had never thought of previously, let alone even existed; the IBM 5161 expansion unit. However, there wasn't much in the article. I would also learn as time went on, that there really wasn't and isn't that much that was ever written regarding the expansion unit. Really, that first article was no longer than a short sentence in a single paragraph. That one line got me started down a path and the eventual direction I would go with the refurbishment and rebuild of my own IBM 5150 Personal Computer system.

When it comes to my hobby of Vintage Computing, not many would have had the luck I have experienced over the last few years. It just seems as if there was something I wanted bad enough, I would eventually get it, and typically for a far better price than what others had been paying. Still, I think even fewer would have the ambition I had when certain opportunities presented themselves. Sure there were risks. One of the risks I took was in accepting a set of extender and receiver cards as a gift from a member of VCF.

My friend in the Vintage Computer Forums didn't have much hope that the cards he was offering me were still functional. In fact, he gave the expansion cards less than a 20% chance that they had any life left in them. I accepted the cards nevertheless.

As luck would have it (my good luck was still on a roll!!!), a new member to the Vintage Computer Forums posted a request looking for an extender card for his own IBM 5161 expansion chassis. These extender cards are almost impossible to find. And when they are found, their owners are extremely unwilling to sell them for fear that they may need one someday in the future. I am one of those individuals. As it worked out, instead of offering to sell my extender card, I offered to buy his expansion unit, minus the SCSI hard discs he had installed. I initially offered to purchase the expansion unit for $125.00, but he refused, and countered with $40.00 plus shipping. Needless to say, I bought that unit! It was, and still is, in almost as good of shape and condition as the rest of the system; meaning that other than a single scratch across the top of the unit, that doesn’t even break the surface of the paint, the expansion unit’s case and interior look as if it was just unboxed for the 1st time. Gathering up a good set of controller and full height MFM drives consisting of a Western Digital controller, and twin Control Data hard discs, my IBM 5161 expansion unit is all but complete. Obtaining the drives and controller took an additional couple of weeks, bringing the final cost of assembling the expansion unit to less than $130.00. Not bad for a period correct setup; especially right now when expansion units are currently selling for as much as $800.00 on E-Bay.

The only thing that really concerned me at the time was the extender and receiver cards. As mentioned, their previous owner only gave these cards about a 20% chance that they would work.

Finally, I had to take the ultimate chance. It was time to boot the system. Everything was set up properly. All of the IRQs were double checked and verified. Cable connections were checked, cleaned and checked again. It was 'now or never'. When I switched the system power to the “ON” position, the computer booted to the C drive on the first attempt! The expansion cards proved to be 100% functional! I had the computer I had always dreamed of, and then some! Needless to say, I was elated! I am still in awe of the system I was able to assemble, and refurbish. The entire setup, including as many IBM labeled components, and peripherals as possible, like the IBM 5150 PC, IBM 5153 CGA monitor, IBM 5152 Graphics Printer, and original XT keyboard is nearly perfect. There are no signs of wear and tear. There are no scratches, dents, rust, or corrosion. In fact, the system is in such a great condition that I have been offered as much as $3500.00 to purchase it as is. Of course, I have had to refuse, since I have almost four years into the project. Possibly one day, but as far as right now, I do not see myself selling this, or any of my completed vintage computer systems. It has actually become the centerpiece of my entire collection.

Here is what amazes me though, and the primary reason for writing this; is the expansion unit. Ever since completing my expansion unit rebuild and restoration; IBM 5161 expansion units have been popping up on E-Bay like crazy! It seems as though another one shows up on E-Bay as often as once every other month; sometimes more often than that, sometimes less. The point being that since completing my expansion unit a few months ago, there have been no less than 5 more of them show up for sale on E-Bay. Today was no exception. I saw another beautifully kept IBM 5161 expansion unit for sale with a starting price of $500.00. The last one which was sold only approximately three to four weeks ago sold for $800.00! The one prior to that also sold for $800.00. The only one I have seen to sell for less is one that a member of VCF had up for sale. In the end he accepted a deal for $500.00 and another piece of vintage computer equipment. So even then, he still got more than $800.00 for his.

Out of mere curiosity, I have been watching E-Bay for more 5161 expansion units. I have watched discussions in the Vintage Computer Forums, and was able to come up with a slightly educated guess of how many of these expansion units there are left in the World which are also still in good working order. Up until I finally completed mine, I thought there were approximately 12. Now that number has risen to almost 20. That is the number I am estimating for these units that are not only still functioning, but also have all of the required extender and receiver cards, and the cable to connect the two. I am sure that for every one that is able to be put to proper use, there have to be at least one or two more that are missing one or more of the required expansion cards, or components; I.E. the extender, or receiver, planer board, etc. And of those that are missing a single component, it is the transmitter, or extender card that is most often misplaced, simply because it is the one component that must be installed outside of the expansion unit, and into a host PC in order to become functional.

So, just how many IBM 5161 expansion Units are there left in the World? More importantly; how many are truly left that are 100% functional? Honestly, I am curious for far more than one reason here. (I have several reasons for wanting to know) But, the main reason is simply because as the numbers of functional units grow, their value as something rare and unique is sure to be affected, and will fall. How far they fall depends on the number of units remaining and the willingness of their owners to sell them. Each is dependent on the other. At what point are the rising numbers sufficient enough to cause prices to drop out from underneath their owners’ feet? When is the sales price going to level out, and more importantly; at what level? In order to guess at these, we really need to know just how many were initially built and eventually sold. Only then, will we be able to obtain any kind of accurate numbers for survivors. The equations are there, and probability studies will be able to back up the findings, but we need to know how many were built and sold before we can apply those equations and studies.

Certainly natural hardware attrition will be the biggest variable we will have to account for somehow. To what degree of accuracy can we expect; 10%, 20% 50%???

Does anyone care to take a guess? Or can someone actually provide us as a group with the answers to these questions?

1. How many IBM 'PC's were manufactured of each mother board configuration? (Related for another study)
2. How many IBM PC/XT systems were manufactured? (Related for another study))
3. How many IBM 5161 Expansion Units were manufactured?
4. What equations would we use to determine the remaining existing numbers of surviving computers and expansion units?
5. What kind of study can we use to determine the accuracy of the above equations?

As more data is gathered, these, and other questions will answer themselves. We have already seen prices drop from the mid $800.00 area to about $200.00, but these prices don’t reflect completely working units. Indeed, when a complete expansion unit is available, which includes the extremely rare and valuable extender card, selling prices should reflect the working status. Sadly though, fully functional expansion units just don’t come up for sale. All of the ones I have seen sell through E-Bay and other sites over the last 18 months have been missing the all-important extender card. Recently though, two extender cards were sold on E-Bay for $100 each plus the cost of shipping. At the same time, a receiver card was also sold for the grand total of $20.00 including shipping. One member of the Vintage Computer Forums purchased all three cards. He needed one extender for his own expansion unit. The other extender and receiver he purchased as spares.

Those who do have a spare extender and/or receiver do not offer them up for sale, preferring to keep them in case they are needed in the future.

Final thoughts

Is this setup perfect? Well, to be honest; no! I personally wish there was room for a mouse; possibly on a side shelf that mounts to one of the front uprights. Then I would like to place the external floppy drive and cassette recorder in such a fashion so that both are on the same side of the computer. With me being left handed, the mouse shelf would need to be mounted on the left side as well.

Finally cable management on this desk is nonexistent. Because of the nature of computer peripherals, one has to deal with power cords. I was able to replace the 6 ft. long power cable that ran from the monitor to the power outlet with one that is only eight inches in length. That made a huge difference. Too bad other cables couldn’t be shortened. Power cables for the expansion unit could be about 30 inches and replacing the power cable from the PC with another eight inch one will certainly make things neater in the back. (Note: I am in the process of looking up shorter cables to replace all of the longer ones, including the printer cable and the parallel cable connecting the external Micro-Solutions floppy drive)

Sadly, there is no room for the obligatory vase containing a single rose!

So much for the faults. Now for some of the things which make this setup work so well. First off, it is very compact. There isn’t much room for distracting objects, or clutter, so it’s very easy to keep clean and organized. Next, it is portable. The entire system can be easily moved from one room in my home to another with minimal fuss and bother. The desk is at the perfect height to work comfortably. Since there is no reason to ever get into the expansion unit, or do anything with it physically, it is out of the way. And, as previously mentioned; placing the expansion unit on the bottom shelf has balanced out the weight distribution so the desk is much more stable while being moved. Lastly; the location of the printer allows plenty of room to print documents, and tear off the pages they are needed.


Veteran Member
Jan 6, 2014
Melbourne, Australia
Very interesting read! I'd also like to know the quantities of PC's and XT's made.

I'm sure there are 5150's, 5160's and 5161's yet to be found in dusty corners of places. I want to be the one that finds them!


Veteran Member
Feb 16, 2012
New Zealand
As silly as it sounds, have you guys tried getting in touch with anyone from IBM?
I know it was a long time ago now, but in the early 2000's I wrote to them about the 5160 (I can't remember why), and they sent me a bunch original product photos of the IBM PC and IBM PC XT + accessories - from New York to New Zealand! I've since framed them for my vintage room, but I thought it was pretty awesome they took the time to write back and send me stuff. Maybe things have changed but perhaps they might make the effort for questions like those too?


10k Member
Nov 3, 2009
South Jersey, USA
In my case, I chose to install the extender and receiver cards into the very last expansion slot, or to be more precise; the furthest expansion slot from the power supply. On the 5150 PC, that will be slot 5. However, the receiver card cannot be installed into a 5160's last slot, or slot 8, because of differences in the expansion of the XT. Slot 8 was configured differently for future expansion options; which won’t be covered in this document.
Actually, the last slot, as you have called it, is slot 1. Slot 8 on the 5160 is the one closest to the PSU.


Veteran Member
Feb 19, 2012
Fort Walton Beach, Fl

I enjoyed reading about the project. I would also be interested in number of 5150's and 5160's PC's IBM produced.



Veteran Member
Dec 13, 2008
Cornwall, UK
4. Original IBM CGA 16 color video adapter with integrated parallel port (Combination card) (LPT1)

I thought it was just the MDA video adapter that had an integrated parallel port - I didn't know any IBM CGA cards had a parallel port as well. Could you take a picture of this card for me?


Veteran Member
Feb 21, 2011
Eugene, OR
Due to some grammatical errors, and spelling issues as well as getting rid of the smiley face "thing" I have decided to copy and paste it to one of my text editors, or MS Word format to fix all of the issues I've seen while proof reading it for possible public publication. If the magazine I'm negotiating with decides to go for it, I'm looking at a nice payoff. However, if they decide to let it go, then only those who visit the Vintage Computer Forums will have access to it.

Wish me luck.

Thomas (AKA bettablue)


New Member
Feb 14, 2016
IBM 5150 PC System - AKA "Alice"
My particular IBM PC is model 5150-184 with a serial number of 1,395,232.

I am intrigued by the part number you quote here. As far as I can discover, yours is the only discoverable mention of this base unit part number on the web. I must admit, I was expecting the '8' digit to represent three 5.25 floppy drives (half-height). So I am finding it intriguing what IBM may have used to drive this digit to '8' - rather than '7' (the usual, for two 5.25 360K drives).

IBM did have a schema for this with the 5150, which is largely deducible if you match part numbers to factory-fitted standard "options", via IBM price lists, announcement letters, etc.

So I'm wondering if it might be related to the hard drive, but you indicate that this is in the 5161 expansion box - where I'd expect it to be. I would have thought it unlikely that the part number of the base unit would depend on that, and am ruling that out.

The next thought is that it my be related to the factory-fitting of the extender card for the 5161 unit. But since I cannot find any other evidence on the web, I am left intrigued but not convinced by that theory. After all, why override a perfectly good identifier digit for floppy drive type and count, in order to show what is usually an optional adapter?

So then I wondered whether this is a typo that rearranged the numbers: 814 perhaps? But I'm 99.9% sure that 814 means factory fitted async card + one 160/180K floppy drive + 64K of motherboard RAM. So I also rule that out your own error by that manner as unlikely - because that numbering of the async card was discarded after they brought out the 64-256K (Revision B) mothercard - which matches the '1' that you quote... And then I realized that you also quote that '4' at the end. This would, on a Rev B board, mean factory-fitted 64K base memory, not 256K. So either the extra 192K was added later or...?

Thus I am very confused by this part number, and would love it if you could clarify whether it is accurate (and by what reference).

By my understanding (limited and hampered by the dearth of available info on the web) this base unit, if all had been fitted in the factory aside from the extender card, should have had the part number 5150-176. Alternatively, if 192K RAM had been added later: 5150-174. And if one of the floppy drives was a late addition: 5150-164, which if adding back that RAM would then be 5150-166. The '1' digit would not change, because of the motherboard driving that (IBM had more or less abandoned the 8xx and Xxx designations by 1983/84). My original suspicion had always been that 5150-184 would have meant three half-height 360K drives, and 5150-194 would have meant the full maximum of four half-height floppy drives. But as I can find no evidence, that remained a theory. Your part number has therefore put a cat amongst the pigeons (that I clearly carry around in my head...)