dale@pro-colony.UUCP (System Administrator) (10/27/87)
GS-RAM and MemorySaver There's been some feedback from GEnie users about compatibility between GS-RAM and the MemorySaver product. Here's some information that may prove helpful to the owners of these products and others who may soon have them. First, Applied Engineering makes no claim that GS-RAM is compatible with MemorySaver. AE claims only that it works in the IIGS memory expansion slot. A review of MemorySaver advertisements and the owner manuals shows that MemorySaver's manufacturer does claim compatibility. Consequently, any problems of compatibility need to be directed to those who claim the compatibility. Preliminary information about how MemorySaver works with GS-RAM indicates that the power supply on MemorySaver may not have enough capacity when using cards that have more than 4 rows of chips installed. The MemorySaver examined was shipped with a 6vDC at 1AMP wall power supply. The DC output with one card, having 4 rows of chips, installed in the unit tested was 7.5 volts. With more current being drawn than that required by one card, the supply voltage drops lower and closer to the nominal 6vDC. Note that in order to charge the 7.2v batteries, the power supply has to deliver the nominal current and voltage as follows: Charge Current | V50ohms | Vout Power Supply ----------------------------------------------------- 40 mA | + 2v | 9.2 volts 30 mA | 1.5v | 8.7 volts 20 mA | 1.0v | 8.2 volts 10 mA | 0.5v | 7.7 volts 6 mA | 0.3v | 7.5 volts Each NiCad = 1.2 volts x6 = 7.2 volts. Nominal charge current is rated at .1x the A/HR rating. The value of 50 ohms is the series charging resistor used in MemorySaver. Measurements taken with a 7.5 volt power supply used to simulate a fully charged battery are as follows: |W/O Line Pwr |With Line Pwr* Apple IIGS power = OFF | Discharge | Charge ------------------------------------------------------------------ Apple Memory Card and MemorySaver | 410mA | + 1mA GS-RAM 1.5MEG and MemorySaver | 510mA | - 1mA GS-RAM 1.5MEG, Apple Memory Card and | 810mA | -10mA MemorySaver | | * Pwr Sply plgd in Once the batteries are discharged below memory sustaining voltage, loss of data may begin to occur. Additionally, there is an input (pin 27) on the GS memory connector. When this pin is driven high, it indicates the use of 256K chips. When this pin is driven low, it usually indicates 1Meg chips or, it could also mean more than 4 rows of 256K chips. Many designs of GS memory cards tie this particular signal to ground or to 5 volts as needed. In other designs, this is an active signal that changes the logic state as necessary. In the MemorySaver examined, this pin is tied together between the two connectors where two different memory cards attach. As you can predict, there will be a short if one memory card has this pin tied to +5 volts and the other card has it tied to ground. MemorySaver may also have problems with other cards that have an active signal at this location. Please accept this information in the spirit in which it is given. My intention is only to inform the more serious users of these products in order to overcome possible problems. Many new products require some initial feedback and corrective effort to stabilize them in the market place. Being patient with the manufactures will provide all of us with products that we can use beneficially. Dale * The editorial opinions are my own and may not be those of my employer. * UUCP: [ ihnp4 sdcsvax nosc ] !crash!pnet01!pro-sol!pro-colony!dale ARPA: crash!pnet01!pro-sol!pro-colony!dale@nosc.mil INET: pro-colony!dale@pro-sol.cts.com proline: [ pro-carolina pro-party pro-sol ] dale@pro-colony pro-colony :-> 1 214 370-7056 - 300/1200 - 24 hrs