SomeGuy
Veteran Member
Ok, have been exploring this early-ish clone board lately, here is what I have found:
This is a Display Telecommunications Corporation "Megaboard". I don't know if it was always called that, or if they referred to it differently when part of a complete OEM system. It is not labeled as such.
The DTC "Megaboard" is an early ~1983 IBM XT clone motherboard. Note this is not the same "DTC" that produced hard disk controller. Also do not confuse with "DTK".
It was the first product of Display Telecommunications Corp. It was sold to OEMs and individuals as bare boards, kits, or assembled. It was used by hobbyists, experimenters and high-tech handypersons.
There is an Infoworld article comparing it to other boards here:
https://books.google.com/books?id=B...Q6AEIFDAA#v=onepage&q="dtc megaboard"&f=false
One ad lists:
Display Telecommunications Corporation
4100 Sprint Valley Rd, #400
Dallas Tx 75234
Bare board $99
Socketed: $249.95
Assembled $599.95
DTC did sell cases and other parts for it.
After clipping a shorted -12v tantalum capacitor, the board works great. Going by the chip dates, this specific board was manufactured in 1984.
The ROMs contains a bootleg of the IBM 5160 11/08/82 BIOS with BASIC. From my research, it normally should have come with its own "megabios". Also from what I have read, supposedly the manual gave instruction how to copy the IBM ROM in to it, which some considered inappropriate.
This board uses the same power supply interface as the PC/XT/AT. A standard AT supply works fine with it.
The board is physically larger than an XT board. It will not fit in an XT or Baby AT case. The Keyboard plug does not line up and the board needs extra space for its reset switch. Still, it is mostly an XT clone and uses the 5160 ISA spacing.
The board itself feels a little flimsy. All chips are socketed. On the one hand, socketed chips can be a bit less reliable, but on the other hand, could be easier to fix. I haven't looked up all of the part numbers, but It uses only basic 74LS chips to interface the main chips. (No PAL programming needed?)
An odd implementation on this board, it has little metal divider shields between the main sections. While that was common on some earlier computers, I don't believe I have seen that on other IBM PC clone boards.
Over all, this is a "no frills" motherboard, but it does have some developer-friendly aspects.
Most visibly, it has perfboard area where one can their own custom circuitry. It features a reset switch next to the keyboard port.
This board supposedly "features" slot 8 support identical to the IBM XT. Although, what was that ever used for? The board also has a card-edge connector that seems to extend the ISA slots.
Jumpers permit ROMs to be configured in a variety of ways.
By cutting/soldering jumper wires, the board can be configured to use either 16k, 64k, or 256k, RAM chips. This board contains a full 640k, although the Infoworld article suggests it would be limited to 256k.
This board has also been maxed out with an NEC V20 and a math co-processor.
Booting it, and throwing software at it, it seems perfectly IBM PC XT compatible. It passes all the diagnostics I have thrown at it. It works fine with VGA, XT keyboards, and an 8-bit 1.44mb floppy controller. Of course, remember this has an IBM BIOS in it.
The only real issue with this motherboard is that it does not physically fit a standard XT case.
Any rate, I think this in an interesting addition to my collection of early PC clone and parts.
This is a Display Telecommunications Corporation "Megaboard". I don't know if it was always called that, or if they referred to it differently when part of a complete OEM system. It is not labeled as such.
The DTC "Megaboard" is an early ~1983 IBM XT clone motherboard. Note this is not the same "DTC" that produced hard disk controller. Also do not confuse with "DTK".
It was the first product of Display Telecommunications Corp. It was sold to OEMs and individuals as bare boards, kits, or assembled. It was used by hobbyists, experimenters and high-tech handypersons.
There is an Infoworld article comparing it to other boards here:
https://books.google.com/books?id=B...Q6AEIFDAA#v=onepage&q="dtc megaboard"&f=false
One ad lists:
Display Telecommunications Corporation
4100 Sprint Valley Rd, #400
Dallas Tx 75234
Bare board $99
Socketed: $249.95
Assembled $599.95
DTC did sell cases and other parts for it.
After clipping a shorted -12v tantalum capacitor, the board works great. Going by the chip dates, this specific board was manufactured in 1984.
The ROMs contains a bootleg of the IBM 5160 11/08/82 BIOS with BASIC. From my research, it normally should have come with its own "megabios". Also from what I have read, supposedly the manual gave instruction how to copy the IBM ROM in to it, which some considered inappropriate.
This board uses the same power supply interface as the PC/XT/AT. A standard AT supply works fine with it.
The board is physically larger than an XT board. It will not fit in an XT or Baby AT case. The Keyboard plug does not line up and the board needs extra space for its reset switch. Still, it is mostly an XT clone and uses the 5160 ISA spacing.
The board itself feels a little flimsy. All chips are socketed. On the one hand, socketed chips can be a bit less reliable, but on the other hand, could be easier to fix. I haven't looked up all of the part numbers, but It uses only basic 74LS chips to interface the main chips. (No PAL programming needed?)
An odd implementation on this board, it has little metal divider shields between the main sections. While that was common on some earlier computers, I don't believe I have seen that on other IBM PC clone boards.
Over all, this is a "no frills" motherboard, but it does have some developer-friendly aspects.
Most visibly, it has perfboard area where one can their own custom circuitry. It features a reset switch next to the keyboard port.
This board supposedly "features" slot 8 support identical to the IBM XT. Although, what was that ever used for? The board also has a card-edge connector that seems to extend the ISA slots.
Jumpers permit ROMs to be configured in a variety of ways.
By cutting/soldering jumper wires, the board can be configured to use either 16k, 64k, or 256k, RAM chips. This board contains a full 640k, although the Infoworld article suggests it would be limited to 256k.
This board has also been maxed out with an NEC V20 and a math co-processor.
Booting it, and throwing software at it, it seems perfectly IBM PC XT compatible. It passes all the diagnostics I have thrown at it. It works fine with VGA, XT keyboards, and an 8-bit 1.44mb floppy controller. Of course, remember this has an IBM BIOS in it.
The only real issue with this motherboard is that it does not physically fit a standard XT case.
Any rate, I think this in an interesting addition to my collection of early PC clone and parts.