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The PB 500 is as far as I can discover the Packard Bell companies first attempt at a IBM compatible machine and I believe was released around 1988 but possibly earlier. The PB 500 has a fairly standard design unlike there later Pentium era cases and seems to run fairly reliably as opposed to the massive reliability issues the company would face later with its products. The PB 500 is basically an IBM XT class clone running on the 8088 CPU but being capable of far greater speed and expandability compared the earlier original PC specs of the IBM 5150.

pb5006

Here we have the front view of the machine. It is a little lighter and more compact then an IBM XT computer. Nothing to fancy on the front. On the lower left is the keyboard port for an XT keyboard. As you can see on the right I have a 20MB hard drive installed in the lower bay and in the upper bay is a 720k floppy drive. This machine originally came stock with a 5.25 inch 360k floppy drive but is capable of being upgraded to the 3 1/2 inch 720k floppy as they previous owner has done here. Generally this is an advised upgrade and I find the 720K drive much more convenient. Since 720k drives are a little scarce if you install a standard and plentiful 1.44mb drive it will function flawlessly in these machines as a 720k drive. I’m running DOS 3.3 on this machine which I believe is the operating system that this machine came standard with.

pb5007

here we have the rear of the machine. there are 5 slots available for expansion cards as well as two built in ports. The port on the right is a parallel port and to the left of it is a serial port. To the left of these ports we have a small dip switch that can be used for setting the ports.

pb5001

Here we have the motherboard in the case with all the drives and expansion cards removed. You can see the five 8 bit ISA expansion slots for add on cards.

1) This is the onboard beeper. This generates all your PC speaker sounds.

pb500cpu

2) Here we have the CPU of the PB 500. This machine comes stock with a 4.77mhz Intel 8088 which was standard for the IBM PC. The PB 500 though is a “turbo” XT board so by pressing [Ctrl]-[Alt]-[ + ] on the keyboard the CPU kicks into 10mhz or more precisely 9.54mhz mode. Pressing [Ctrl]-[Alt]-[ – ] returns the CPU to standard 4.77mhz. The change in CPU speed is accompanied by a change in the power LED light from orange to green which is a nice touch. When I received this machine as you may be able to tell from the motherboard image it had a NEC V20 installed which is pin compatible with the 8088. The V20 is very compatible with 8088 software but due to improved efficiency boosts the speed of this particular machine to the equivalent of 8mhz when running in 4.77mhz mode and 15mhz when in 10mhz mode. Although the NEC upgrade is generally an advised upgrade for these machines I decided to use this PC as a sort of base line machine and for complete 8088 compatibility I replaced the V20 with an AMD 8088 CPU. Also to note a very minor side effect of the V20 upgrade is that the LED will not color change when turbo mode is selected.

3) This is the slot for the optional math coprocessor the 8087-1. As you can see this machine is without one.

4) The connection for the XT keyboard port.

5) The chips to the left of the # 5 are the RAM chips. This machine is expanded to its max of 640k of ram. To the right of the #5 is the wire that connects the LED to the motherboard.

6) This is the onboard interface for the floppy controller. The PB 500 supports 360k and 720k floppy drives. Unfortunately this cannot be deactivated so you can’t upgrade to a high density disk controller via an expansion slot.

7) This is the standard AT power connector for the board. Below that you can also make out the blue barrel nickel cadmium battery. These need replaced every few years else they can leak and corrode your motherboard.

pb5005

Here is a shot of the internals with all the drives and expansion cards in place. As I said before the hard drive that came installed with this machine is a MFM half height 20MB hard drive that you can barely see below the floppy drive and cables. Since this machine was found at a thrift neither I nor the buyer I received this from knows if the video card and HDD controller came stock with this machine.

1) The PB 500 lacks any onboard video so in order to have the machine display a video card is required. In a way this is nice since you get the option to choose your video card and not have to worry about disabling any onboard video chip. The PB 500 can accept any 8 bit video card. I decided to go with CGA over VGA or EGA since most VGA games run far to slow on this machine and I have much better machines for EGA. The card that came with this PC was the ATI small wonder CGA card which is a very nice CGA card in my opinion. The ATI small wonder can do CGA as well as Hercules/MDA, Plantronics, and ATI’s own 16-color 320×200 and 640×200 graphics modes. It also has a header for a composite jack. This card has a home made composite connection routed through the gap where the cards dip switch is. It looks a bit crude but I like it since it means I do not need to take up another expansion slot for the composite jack bracket.

aticga

I really like this card and it seems to work really well.

pb500cga

Here’s a shot of Leisure Suit Larry in the Hercules mono mode and next to it is F-15 Eagle in CGA mode. This is taken on my Tandy CM-4 CGA monitor.

2) This is the 8 bit MFM hard drive controller. Since the motherboard doesn’t have a built in controller an expansion card controller is required. This particular card is from Western Digital and supports 10 or 20 MB MFM drives.

mfmcn

Overall the PB 500 is a pretty nice compact XT class machine for playing older CGA games that require that slower 4.77mhz CPU. Couple that with the turbo mode and the option to replace the 8088 with a NEC V20 if you desire and you have a pretty capable early to mid 80’s machine. You also have the option to add an 8 bit VGA card or EGA card if you wanted to play some later games though in my opinion even in turbo with the V20 most VGA games are just going to be to taxing. One of my issues first off is the fact you cant disable the onboard floppy controller and cant add a controller for high density 1.2MB and 1.44MB drives. Also from what I’ve read this machine is very picky about what 360k drives it will work with. Finally by this time many XT class machines like the IBM 5160 came with eight 8 bit ISA expansion slots so the mere 5 found on the PB 500 is a very minor disadvantage overall. Despite that it’s still a nice 8088 machine and doesn’t take up a lot of desk space.

pb5002

Update 7/19/16

I recently picked up another PB 500 that appears to me more or less stock so I just wanted to post a few images of what it looks like and the expansion cards I found inside.\

pb500c

pb500b

The CPU I found installed was a Siemens produced chip.

pb500a

 

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4 Comments

  1. Very similar to what I have. Now if only I could find a keyboard like the one you have in this pic… as you probably know but I didn’t, a regular ps/2 keyboard with an adapter just won’t work on my PB 8088 😦

    • yeah, you need a PC/XT keyboard. there connectors look identical to the later AT keyboards that WILL work with a ps/2 adapter and vis versa but the PC/XT ports are electronically different from AT or PS/2. be careful if buying one off eBay as a lot of sellers have no idea about the difference and just mark the way more common AT keyboards as PC keyboard…or i see PC/AT a lot to which is possible since I think there were some that had switches for pc/xt mode and at mode…just ask questions of any seller first.

  2. This was my family’s first computer. We had the 5.25″ floppy drive, but other than that, it’s the machine I learned the basics with. We even had a similar CGA monitor and a copy of Leisure Suit Larry. Sierra made cool games back then.

    • I have a plan to replace that massive MFM drive with a Compact Flash hard drive so I can put a 5.25″ 360k floppy in that bottom drive bay but I’ve had no luck so far getting a 8-bit controller to work right in this machine even though it works fine in other machines I have. But then that’s a Packard Bell for you.


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