This is the soldermasked and silkscreened reproduction MP-A. Two jumpers were added so it is not necessary to cut traces and add wires to use an SWTBUG ROM. The 6810 EPROM can be enabled or disabled by a jumper.
For comparison here is an original SWTPC MP-A board.
The MP-A reproduction shown without a solder mask
The MP-A was reproduced to allow for authentic restoration of an original SWTPC 6800 computer or for someone who wants to have the same experience as when SWTPC released their computer back in 1975. If you are looking for a 6800 SS50 processor board for general use we recommend either the MP-A2 or Corsham 6800 reproduction processor board. The MP-A has limitations that make it harder but not impossible to expand your system.
The MP-A is available in two versions. One version has a soldermask and silkscreen which the SWTPC board did not have. The solder masked version of the board was changed so you don't have to modify the board to use SWTBUG. There is another jumper to enable or disable the 6810 RAM chip. This is necessary when running FLEX since FLEX needs 8K of memory at addresses A000-BFFF. The RAM chip is at address A000-A07F.
The other version of the board is a very close reproduction of the SWTPC board. It will be necessary to cut traces and add wires if you wish to use SWTBUG. This board, however, is an almost perfect copy of the original SWTPC board.
To boot from a floppy without entering a bootstrap loader by hand, you need to use SWTBUG. MIKBUG does not have a command to boot from floppy. A SWTPC DC-1 or Peripheral Technology FD-1 was board was typically used with the MP-A. A DC-2 or DC-3 floppy controller is also compatible with this board.
If you want to use a double density floppy controller you should consider using an MP-A2 processor board. You would end up making a lot of modifications to use the MP-A when the MP-A2 is much better suited for the purpose.
Since MIKBUG or SWTBUG ROM monitors are extremely hard to find an adapter board is available to allow a 2716 to plug into the 6830 ROM socket.
The MP-A does not ship with a boot ROM since the original boot ROMs are very hard to find. If you need a boot ROM, order the 6830 to 2716 adapter board. We can supply MIKBUG or SWTBUG in the 2716 EPROM, but we recommend SWTBUG if you are unsure as to what you want or need.
SWTPC 6800 MP-A Processor board
| MP-A | Assembled and Tested - 921 KHZ clock - no soldermask - no Boot ROM | $99 |
| MP-AS | Assembled and Tested - 921 KHZ clock - soldermask/silkscreen - jumpers for MIKBUG/SWTBUG - no Boot ROM | $99 |
| MP-A-BARE | Bare MP-A Board - No soldermask or silkscreen - No Boot ROM | $20 |
| MP-AS-BARE | Bare MP-A Board - Soldermask and silkscreen - jumpers to select MIKBUG/SWTBUG - No Boot ROM | $20 |
| 6830-Adapter | 2716 to 6830 adapter, includes 2716 and either MIKBUG or SWTBUG programmed in a 2716 | $15 |
| PT-SS50-64K | 64K memory board - 32K usable unless MP-A is modified | $39 |