The SINGLE -CAS ADAPTER (p/n INN-8448-13) provides a testing solution for two types of special 30-pin SIMM modules: the SINGLE -CAS MODULES and the modules with PARITY BIT EMULATION LOGIC CHIPS.
The JEDEC standard for 30-pin SIMM modules requires the use of two -CAS (Column Address Strobe) control lines. The first one, at pin 2, is marked -CAS and is used to control the eight data bits of the module. The second one, at pin 28, is marked -CAS9 and it controls the ninth bit (parity bit). Since most applications connect the -CAS and -CAS9 to a single source on the motherboard, some module manufacturers use a single -CAS control line for all the nine bits. These include some of the 16Mx9 modules which are made of 36 4Mx1 chips, and most of the x9 modules which use a set of three special x3 chips. When you test these modules directly on SIMCHECK, they will be detected as x8 modules, since SIMCHECK was designed for the JEDEC standard. This optional adapter is designed to accommodate such 30-pin modules with a single -CAS control line, so that they can be tested as x9 modules.
In an effort to reduce the cost of memory modules, several companies have developed parity-bit-emulation logic chips for 30-pin SIMMs. These parity-bit-emulation chips, like the GS81C4100J70 or BP41C1000A-6, use logic to emulate the parity bits on such modules, instead of the real (and more expensive) memory devices which are required for true parity function. Such modules, which contain x8 real memory devices plus the parity-bit-emulation logic chips, can be used on computers which require the standard x9 bits. Since the parity-bit-emulation logic chips monitor the data read from the x8 memory devices on the module and always compute the correct parity bit for that data even if the data was corrupted, they actually disable the benefits of the parity feature as defined by the IBM standard PC architecture. As mentioned above, true parity function must include a real memory device to store all individual parity bits for each stored byte. Since SIMCHECK was designed to be a memory tester, it can test logic devices only with an external adapter such as the SINGLE -CAS ADAPTER.
Connect the adapter to your SIMCHECK SIP ZIF (green) socket when SIMCHECK is either ON or OFF. Insert the module into the SIMM ZIF socket of the adapter. The socket will accept the module only in the correct orientation.
CAUTION: Do not use excessive force to insert the module as you may break the insertion pins on the socket's levers.
Once the module is inserted, press F1 to start the test. The test is exactly the same as our regular 30-pin module test, with the exception that the Page mode test section of the EXTENSIVE test is currently not included.
DETECTION OF PARITY-BIT-EMULATION LOGIC When SIMCHECK detects a module which employs the parity-bit-emulation logic, a message saying BIT9: PARITY BIT EMULATION LOGIC will appear. The test will then proceed with the normal SIMCHECK test in progress (TIP) animation with the letter 'p' placed at the position of bit 9. The final test result will describe size with the suffix p such as "1Mx8p".
Required EPROM Version: 2.32 or above
