Intel Above Board 2 Plus

@7788.ADF Intel Above Board 2 Plus
I7788.ADF Init file for @7788.ADF (version 1)
I7788.DAT Alternative init file for @7788.ADF? (version 5)
@FEFE.ADF IBM 2 MB 16-bit Memory Adapter (for Above Board 2 Plus)
CFEFE.ADF Init file for @FEFE.ADF (for Above Board 2 Plus)
   So which adapter ID is correct? Both?

AB2PLUS.ZIP Option Diskette for 2 Plus (zipped image, from David Beem)

Intel Above Board Support Pages (archived)
Intel Above Board - Installation Problems and Solutions
Initializing ADF Description

Above Board 2 Plus
DIP Switches (U22)
SIMM Compatibility

Some of the information on this page came from William R. Walsh's website (original HERE).

Above Board 2 Plus (Adapter ID FEFEh or 7788h?) [P] [P]

This "pretends" to be an IBM 2 MB 16-bit Memory Adapter, like the Orchid RAMQuest II.

1-8 30-pin SIMM sockets
U7 Dallas DS1000C-8009 Delay Line
U12 Intel PCEO 301237-001 Gate Array
U14-16 Cypress CY7C149-35PC 1Kx4 SRAM
U18 Dallas DS1000C-8010 Delay Line
U20 Intel PCEO 301252-001 Gate Array
U22 DIP switch (4 positions)
U23 Empty 8-pin DIP socket (?)

1-8 30-pin SIMM sockets. Uses 256 KB parity SIMMs and probably needs them in pairs.

Caution: When loading SIMMs into this adapter, be careful! Some if not all samples use plastic SIMM sockets, and these are incredibly easy to break. A repair doesn't look to be nearly as easy.

"PCEO" stands for Intel's Personal Computer Enhancement Operation. The PCEO was the group responsible for the development and marketing of the Intel Above Board family of adapters.

DIP Switches (U22)

From William Walsh (edited):
   I installed it, ran QBMCA for the adapter ID, and started fiddling with the DIP switches in a test bed machine. With no RAM installed (and probably running the adapter in a machine that's way too fast for it - a Model 53SLC2) the switches did nothing, caused odd video colors at POST or made the machine fail to start entirely.

Tim Knight said (edited):
   I think I read something years ago that each one of the dip switches represent 512 KB memory installed. However, I lie a lot... (give it a try). Don't forget to experiment with SOFTSET - you will need it.

David Ress said:
   From the Fall 1988 Special Edition of BYTE, I found an Intel Above Board/2 (16-bit adapter) listed that supports a maximum of 2 MB of RAM, uses 256 KB SIMMs, either 100 or 120 ns. The adapter may be configured for Extended Memory use and is compliant with EMS 4.0. It originally cost $445 with 0 KB on board, it included RAM disk drivers and print spooler software. Warranty was for 5 years.

This issue lists 25 memory boards and specs that were available as of Fall 1988.

I have another issue at home that explains why you are seeing the same adapter ID on this adapter as IBM 2 MB adapter. Basically, it was done this way to make it easy for manufacturers to get into the MCA arena.

SIMM Compatibility

Source: SIMMs For The Above Board 2 Plus

The following table lists the SIMMs that Intel has verified are compatible with the Above Board 2 Plus. You can't use these SIMMs on the Above Board 2. The table lists both the part number on the module ("bottom side" of the module) and the part number on the DRAMs ("topside" of the module).

You can't mix 256 KB modules with the 1 MB modules on the same Above Board 2 Plus. You must use at least 100 ns RAM for the Fast Ram feature.

ManufacturerModule Part Number
("Bottom side")
DRAM Part Number
256 KBFujitsuMB85227-xx MB85240-xx81256-xx 81C258-xx
Micron TechnologiesMT9259M-xxMT1259EJ-xx
Texas InstrumentsTM4256GU9-xx TM4256EU9-xxTMS4256FML TMS4256FML
1 MBFujitsuMB85235-xxMB81C1000-xx
Micron TechnologiesMT8C9024M-xxMT4C1024-xx
NMBMM1M00J9 GED100S9P09SAAA1M100J-xx AAA1M100J-xx
Texas InstrumentsTX024EAD9-xxTMS4C1024-xx
ToshibaTHM91000S-xx THM91000AS-xxTC511000AJ-xx TC511000AJ-xx

"xx" = chip speed rating. "15" = 150 ns, "12" = 120 ns, "10 = 100 ns, etc.

Note: IBM SIMMs are incompatible with Above Boards.

Note: There are 2 types of 1 MB SIMMs. The SIMMs listed here contain 9 memory chips per SIMM Module. SIMMs that were built using 4 MB technology (these contain only 3 memory chips per SIMM Module) have a completely different timing structure and are not compatible with the Above Board 2 Plus.

Content created and/or collected by:
Louis F. Ohland, Peter H. Wendt, David L. Beem, William R. Walsh, Tatsuo Sunagawa, Tomáš Slavotínek, Jim Shorney, Tim N. Clarke, Kevin Bowling, and many others.

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