Mainboard 81-184

The 81-184 boards are part of the "Universal" boards. They can be found in the 4X, New 2, ...

4X

This is a closeup of the 4X board. Note that U53 is populated and that U60 has resistors replacing it. This is required for the Drivetec Drives.	This is a New 2 board which does not have Drivetec drives and does not have U53 but does have U60.

Mods

74LS139 Mod

If you find a 74LS139 in the front "SPARE" U70 socket you may have a Mod to allow for more than two drives. See page 93 of Micro Cornucopia Apr-May 1986 for details. Link here.

Unknown Issues

"The 74LS373 (U6) is reportedly the culprit when the centronics port goes to lunch (makes sense)."
(Micro Cornucopia, Oct 1984)

"If you are having autodialer problems, you can check out your dialer chip (U19) by selectlng pulse mode in Superterm's dial menu and then listening to the chip (you can actually hear it work). If you don't hear anything, suspect either the TMS 99531 dialer or the Z80A. As we reported last issue, some people are reporting that their system is locking up during dialing and many of them have been told to replace their Z80A with a Z80H."
(Micro Cornucopia, Oct 1984)