I didn't come into the IBM PC scene until around 1986, so that stuff is out of my range of experience. I'd be interested in two things though:

1. I'd like to see pics if you build this monster.

2. Was much of anything released on 720KB 3.5" disks that would run on that generation of hardware? 3.5" disks didn't really catch on much until they took over at the end of the 80s from what I remember, and by then it was mostly the 1.44MB variety (although I think I have a couple of 720KB original game disks laying around somewhere).

The reason for the 720KB drive is to make file transfers from my main PC, where I have my booter images stored, to the IBM PC, which will be in the basement. I can't use a null-modem cable to transfer, especially considering the smallness of the drive. Also, I have some booter images that require a 720KB floppy. I know of no PC booter game that comes on a 1.2MB or 1.44MB Floppy Disk.

Essentially, what the picture will look like is that one monitor will be sitting on top of the 5150 unit and the other will sit on the 5161 unit, if I can find the 5161 at a reasonable price. In that case, I will put the MDA card in the 5161 because it has its own clock crystal, rather than the CGA, which uses the ISA bus clock. The 5150 and 5161 clock crystals may not be in sync. The MDA is not vital at all for playing games, but it just feels right to have one.

My other candidate for a super PC is to obtain an IBM PC AT, with a third BIOS w/512KB + 8MHz 80286 of RAM and the following options:
80287 co-processor
1.2MB and 1.44MB Floppy Drive + Controller
30MB Hard Drive + Controller (may only require one controller)
Hercules Graphics Card
IBM EGA w/256KB of RAM (two upgrades required)
IBM 5154 Enhanced Color Display (A/B switch between Hercules + EGA)
IBM Serial Adapter
Adlib Sound Card
IBM Game Adapter

My first PC was a Wyse 286 clone, which I used from around 1986 to around 1992:
8MHz Intel 80286 + 80287 math coprocessor
1.2MB and 360KB 5.25" floppy drives
40MB MFM hard drive
EGA graphics adapter (unknown brand) and monitor (later downgraded to Hercules monochrome and then upgraded to Paradise SVGA)
640KB RAM (1MB actually I think, but the system used a lot of the address space for other things)
Third-party game adapter (2 joystick ports on an 8-bit ISA card; added this at the same time as the SVGA upgrade around 1990)
2 ISA expansion cards that each provded 1 serial and 1 parallel port
Logitech 3-button serial mouse (later replaced with Microspeed trackball)
AT keyboard
MS-DOS 3.21 (originally, but upgraded incrementally over time to DOS 6.0 or so; Also ran Windows 2.x and 3.1 on it once in a while)
Sound Blaster 2.0 (added in 1991 or 1992)

You can play a lot of classic games on a system like that. Wolfenstein 3-D was about its limit, which could only be played with a reduced view size. X-Wing ran great, except that it required extra RAM for the sound samples.

A 386 would almost be better, though, since they often still had a turbo button that would allow you to slow the CPU to XT speeds.

The IBM printer I want is a dot matrix, Model 5152.

I will connect the MDA to an IBM 5151 Monochrome Monitor and the CGA to an IBM 5153 Color Display for dual-mode action (twenty years before its time.)

No composite monitor?

I have a 32" TV for a composite monitor in the same room. IBM never put out a color composite monitor for the PC (they did have a composite amber screen in the Portable and a green screen for the Convertible.) 100% IBM is the theme of the system, so I would have to use an AppleColor IIe or IIc for a "real" composite monitor.

I don't think I will be able to find a 5161 expansion chassis, and I have heard that it isn't the most reliable way to connect certain cards. That leaves the PC with five ISA slots. I don't want an XT because they lose the cassette interface. Their second and third BIOSes are closer to ATs than 5150s, which means they are less compatible with software that expects a PC (Flight Simulator for example.) The only advantage to an XT, first BIOS, over a PC, third BIOS, are the three extra slots and a better power supply.
Therefore, the PC will have an IBM CGA Card, MDA Card, Serial Adapter, Game Adapter and Floppy Controller in its five slots. Two-Full Height 5.25 360KB Floppy Drives, 8087 co-processor, 256KB of RAM, 5151 Monochrome and 5153 Color Displays, 83-Key Keyboard and 5152 IBM Dot-Matrix Printer. I may switch the MDA for a Parallel Adapter if it becomes too taxing for the 63.5W Power Supply. This is probably the Ultimate IBM PC 5150. Everything that is supported by the third BIOS and hardware is present and nothing else.

My only other, affordable option for the basic PC is really an IBM PCjr. While that system has its advantages, it has a slew of faults. But really compatibility is the key issue. Later adapters don't seem to be particularly constrained by the CGA limitations. I know that with a PCjr., EGA, MCGA or VGA you can select any 2/4 of the 16 available colors in a CGA compatible graphics mode (320 or 640). This will undoubtedly cause errors with games that custom program the CGA palettes. Moreover, some booter games expect 256KB of RAM free. That does not mean 240KB free, which is what the result would be because the PCjr. uses 16KB of system memory for CGA emulation. No DMA controller would cause much frustration as you lose keystrokes to disk seeking. The numbers of sidecars to add on would become large. Too many proprietary slots, too little custom software.

Also, I don't know of any booter game, that only supports an CGA card and requires more than 256KB of RAM. Some booters require more, but they support EGA.

I found an IBM 5161 Expansion Chassis for you...

http://www.vintage-computer.com/ibm_pc.shtml

Look at the May 14, 2005 post. I sent an e-mail to Adam, who replied that it is still available.

Thanks for the tip.

As much as I want a PC, I may be better off with an XT, first BIOS. There are six principal reasons for this. First, It has eight slots, enough for just about everything. Second, it has the power supply to power them all. Third, it is highly likely to come with a 10MB hard drive, slow though it may be. Fourth, while it may only support 128-256KB out of the box, it can be modded for 640KB by adding one LS chip, the RAM and a tiny bit of soldering. This will save a slot. Fifth, it may boot up a little faster than a PC.

If I had an XT, I would populate the slots as follows:
Floppy Controller
Hard Drive Controller
CGA
MDA
Asychronous Communications Adapter
Game Adapter
Real Time Clock Adapter

Now, there are only three problems with this setup. First, the XT BIOS is too old to support 720KB Floppy Drives or Ehanced 101 XT-Keyboards. They drives will appear as 360KB Floppies and unless a DOS Driver is loaded. Second, I will lose the cassette tape interface. Third, while I am pretty sure I am not 100% positive that this machine will be 100% compatible with all software written for the IBM PC.

If I obtained a third BIOS XT, it would come with 640KB on the motherboard without any modification. It would also support 720KB drives and 101 Enhanced XT (no LEDs) Keyboards in the BIOS. However, the BIOS was expanded to 32KB and is organized like an ATs, so will that affect compatibility? Would Mircosoft Flight Simulator 1.0 refuse to run on it or to accept keyboard commands?

IBM PC/XT 5160

05/09/86 BIOS
8087 Math Coprocessor

Floppy Diskette Adapter
ST-506/412 Fixed Disk Adapter
Hercules Graphics Card
Enhanced Graphics Adapter
Dual Asychronous Communications Adapter
Dual Asychronous Communications Adapter
Printer Adapter
IBM 5161 Expansion Chassis Communications Card

(Inside Expansion Chassis)
ST-506/412 Fixed Disk Adapter
Floppy Diskette Adapter
Sound Blaster 1.0-1.5 (w/CMS) [Sound Blaster 2.0-2.01 if you can use CMS upgrade.]
Roland MPU-IPC or IPC-(T) w/Roland MT-32 or CM-32L or Yamaha FB-01
Printer Adapter w/Covox Speech Thing
Covox Sound Master
Innovation SSI-2001
IBM 5161 Expansion Chassis Communications Card

4x 20MB MFM Fixed Disk Drives (Half-Height)
2x 360KB & 2x 720KB Diskette Drives (Half Height)
101-Key Keyboard

IBM 5151 Monochrome Display
IBM 5154 Enhanced Color Display
IBM 5152 Dot Matrix Printer or 5182 Color Printer

A true beast in every sense of the word, this is a PC on steroids! Unfortunately we cannot boast 100% IBM, this is truly a swiss army knife of early standards! EGA covers CGA and is fully upgraded to support 640x350x16 resolutions. Also, the Sound Blaster also covers both Adlib and Game Blaster. The Covox and Innovation (if you can find one) cards boast unique methods of making music. The 2nd printer card is for a LPT DAC like the Disney Sound Source or Covox Speech Thing, and the third is present because the IBM PC and XT can support three ports. One serial port is for the mouse, another for an external modem, and two more because a PC supports four serial ports. The Hercules includes a printer port for a printer. I included a 100% compatible Roland Midi Interface to connect to whatever devices you could find. Each hard drive controller is paired to two half-height hard drives and each floppy controller is paired to a pair of half-height internal drives. The keyboard has 101 keys but no status LEDs. Comes with 640KB on motherboard.

I believe my Sound Blaster 2.0 still had the option of a CMS upgrade.

Also, you may not be able to play composite mode CGA games on an EGA setup.

I believe my Sound Blaster 2.0 still had the option of a CMS upgrade.

Also, you may not be able to play composite mode CGA games on an EGA setup.

Indeed, the SB 2.0 has the option, but it requires a PAL chip that the 1.5 doesn't. Nobody has figured out how the chip is programmed, so the CMS upgrade is not feasible. In an SB 1.5, I would simply obtain a pair of SAA-1099s from an obscelete IC supplier and insert them. As for the composite CGA, is it absolutely certain that IBM never produced an upgrade card that connects to the EGA and uses one or both of the composite video outputs?

There are problems with the configuration I posted above. First of all, I don't know whether the Dual Asychronous Communications Adapters are 8-bit or 16-bit ISA cards, and I strongly suspect the latter (being AT and PS/2 born.) Also, you shouldn't use the Roland MPU-IPC because it doesn't allow you to change the IRQ settings, but the MPU-IPC-T does. Besides, it just doesn't feel right, so I give you the revised version:

IBM PC/XT 5160

05/09/86 BIOS
8087 Math Coprocessor

Diskette Drive Adapter
Roland MPU-IPC-T w/Roland MT-32 and Yamaha FB-01
Hercules Graphics Card or Monochrome Display and Printer Adapter
Enhanced Graphics Adapter or Color/Graphics Adapter
Sound Blaster 1.0-1.5 w/CMS chips
Fixed Disk Adapter
Asychronous Communications Adapter
Asychronous Communications Adapter

2x 20MB MFM Fixed Disk Drives (Half-Height)
2x 360KB (Half Height) & 2x 720KB Diskette Drives (Half Height)
101-Key Keyboard

IBM 5151 Monochrome Display
IBM 5154 Enhanced Color Display or IBM 5153 Color Display

Here is how the IRQs would work:
2 EGA
3 COM2/MPU-401
4 COM1
5 Fixed Disk
6 Diskette
7 LPT1, SB

The Roland would have to go on IRQ3 and the Sound Blaster on IRQ7. This will conflict with the second serial port and the parallel port, but thats why you use a serial mouse on the first serial port and make sure that you aren't printing and playing music at the same time. Also, if you use the second serial port for a modem, make sure you aren't using the Roland midi port (use the Sound Blaster's.)

Great Hierophant wrote:

If I obtained a third BIOS XT, it would come with 640KB on the motherboard without any modification. It would also support 720KB drives and 101 Enhanced XT (no LEDs) Keyboards in the BIOS. However, the BIOS was expanded to 32KB and is organized like an ATs, so will that affect compatibility?

My 5160 has BIOS dated 01/10/86. I don't know where that falls in the first,second, or third order of things. But it has onboard 640K, two 360K DD drives, and a 101-Enhanced IBM XT Keyboard.

Oh, and BTW, I just found out the hard way that Aida-16 crashes when run on either an 8088 or a NEC V20. 😢
But it will run if when I put in my Orchid Tiny Turbo XTra card in. 😁

I wonder if Aida-16 uses any 286 specific registers.

My 5160 has BIOS dated 01/10/86. I don't know where that falls in the first,second, or third order of things. But it has onboard 640K, two 360K DD drives, and a 101-Enhanced IBM XT Keyboard

That is the second BIOS. It supports 720KB floppies, so feel free to install them if you have the room and can find them. Actually, I have heard that there may be difficulties with the keyboard in the newer BIOSes so I am strongly leaning towards a much more common first BIOS. Unfortunately I would lose the 720KB support.

This is the best configuration I can make for an IBM PC 5150:

8087 Math Coprocessor

Enhanced Graphics Adapter/Color Graphics Adapter
Diskette Drive Adapter
Hercules Graphics Adapter
384KB RAM Card (non-IBM)
Extender Card

Asychronous Communications Adapter
Asychronous Communications Adapter
Fixed Disk Adapter (Xebec 1210)
Roland LAPC-I + MCB-1 (w/jumpers)
Adlib Sound Card
Creative Game Blaster
Game Control Adapter
Receiver Card

IRQs work as follows:
2 - EGA
3 - COM2/MPU-401
4 - COM1
5- Fixed Disk
6 - Diskette
7 - LPT1

2 x 360KB Diskette Drives (Full Height)
2 x 20MB MFM Fixed Disk Drives

You can support at least five different sound standards with this setup, Adlib, Game Blaster, MT-32, Music Feature (with Yamaha FB-01), LPT DAC!

You might ask why I made these choices. Well, to start with, I wanted to keep the system as many 100% IBM parts as possible. I also wanted it to support as many older standards as possible. All this is not only to create a machine most likely to be compatible with a given game, but also to give the widest array of audio and video options.

I am very strongly considering removing the Enhanced Graphics Adapter, a difficult and expensive card to put together ) it needs a daughterboard and RAM for the full 256KB for a PS/2 Display Adapter (rarer, but doesn't require any upgrades and can use VGA monitors.) If it doesn't use an IRQ, (fat chance), then my choice is firm.

Why use an Adlib instead of a Sound Blaster? Well, partly to use the Game Blaster, which is not absolutely certain on early Sound Blasters. Also, I preferred to use IBM's Game Control Adapter than Creative's. I will keep a SB Pro as backup, however, for any game that demands SB Midi or SB DSP. If there are any interface or sound differences between the Adlib and the Sound Blaster, it would be better to use an Adlib with this computer.

I have made sure that the system includes two Async Adapters, one for COM1 and the other for COM2. This makes a standard two COM ports, even if the PC can support four. IBM's Async cards cannot really do COM3 or COM4 without cutting traces. One serial port will be used for a Microsoft Mouse and the other will be for a null-modem or an external modem.

I have decided to use two graphics cards in the system. Fortunately, a PC can support this if one card is a mono card and the other is a color card. In this case, the Hercules can be the mono card, as there are no advantages to using an MDPA instead. For the color card, I will use IBM's EGA card and keep an IBM CGA card around for composite color and compatibility. If I decided to use IBM's PS/2 Display Adapter and it did not support a second card, then I would replace the Hercules with a Printer Adapter.

The printer adapter will be used for a Covox Speech Thing or Disney Sound Source. I could substitute a Roland MPU-IPC-T for the LAPC-I, but the LAPC-I is better. Not only does it have the sync function, it also has an LA sound source. The external box can be used for connecting a Yamaha FB-01 for games that support IBM's Music Feature Adapter or an MT-32 if you want to read sysex messages or find a rare game that simply sound perfect with anything less than an MT-32. However, because the IRQ is not selectable with jumpers on the MPU-IPC or MIF-IPC midi interface adapters, you really should use the later cards to avoid a crippling IRQ conflict with the video adapter.

IBM's diskette adapter will support four drives, but that isn't necessary. The IBM PC will support 720KB floppy drives, but only 360KB will be available on disk. In this case, I may include an external drive just for a crude method of transfer from my main PC.

If you're not going for 100% IBM why not add a SCSI HD controller rather than MFM. My XT clone has a 4.5G HD, although it can only see ~2G of it. Then get a Floppy controller with BIOS support for 1.2 and 1.44 floppies. Also, Video 7 made an 8bit ISA VGA card that could also do EGA, CGA, and MDA modes and has dual output so you can, in theory, drive VGA and say, MDA at the same time. Oh yeah, I'd trade the clock card for a NIC and get the time from another system on the network. Then you can also get your games and lose the sneakernet. Of course, this may mean more TSRs.

Not sure how all this would work with the old games, however.

Great Hierophant wrote:

IRQs work as follows: 2 - EGA 3 - COM2/MPU-401 4 - COM1 5- Fixed Disk 6 - Diskette 7 - LPT1/LPT2/SB […]
Show full quote

IRQs work as follows:
2 - EGA
3 - COM2/MPU-401
4 - COM1
5- Fixed Disk
6 - Diskette
7 - LPT1/LPT2/SB

This makes me wonder, why did they choose IRQ2 for MPU-401.

Take "David Wolf" by Dynamix as an example. It uses EGA (or CGA) and Mt-32 in intelligent mode (or Adlib, or PC Speaker). I have checked my LAPC-I [in 386, Tseng ET4000 (VGA)]. When LAPC-I is set to IRQ2 game works OK, but when I change it to IRQ3 or IRQ5 the game doesn't play music (only some single notes are played from time to time). Game's setup doesn't allow us to set IRQ for Roland. Is it possible to change IRQ for EGA?

So how to play this game with EGA and Roland??

How game developers expected us to configure our hardware??

So how to play this game with EGA and Roland??

How game developers expected us to configure our hardware??

Well, I don't know if you can change the IRQs on the IBM EGA, but IBM liked setting standards. In the PC there are only 7 IRQs available, and in the beginning of the PC, IBM decided that IRQ0 would be used for the system timer, IRQ1 for the keyboard controller, IRQ3 for COM2, IRQ4 for COM 1, IRQ6 for the diskette controller, IRQ7 for LPT1 and NMI for the math co-processor. After IBM finished, only IRQs 2 and 5 were available. Their fixed disk controller, found in the PC/XT monopolized IRQ5 and only IRQ2 was left for the EGA.

Also, the EGA is an 8-bit card because it had to work in the PC and XTs. This means that the upper IRQs of the AT and better computers are not available to the EGA. Also, IBMs VGA ISA card is also 8-bit so no dice there, and I have seen a close-up picture of it and it has no dip-switches or jumpers to change settings. Simply put, you can't do Roland and EGA unless you use a non-IBM card, preferably with an AT or better, or hack the program to use a different IRQ.

Great Hierophant wrote:

IBMs VGA ISA card is also 8-bit so no dice there, and I have seen a close-up picture of it and it has no dip-switches or jumpers to change settings. Simply put, you can't do Roland and EGA unless you use a non-IBM card, preferably with an AT or better, or hack the program to use a different IRQ.

I have tried my Paradise PVGA1A-JK 256kB (8-bit ISA, VGA) card (It has many jumpers, but I have no documentatnion, so I don't change them, and also don't know what IRQ does it use). David Wolf works fine with this Paradise and LAPC-I (with IRQ2).