On the initial 8580 models, only 1 MB and 2 MB planar memory modules
were available. With the announcement of the 25MHz planars (8580-Axx),
4 MB memory cards became available. However, it has been discovered that
they will function on the 20 MHz planars (thanks to Tim Clarke and Joe
Kovacs for this discovery). A summary table of my experiences using
various sizes of memory cards in each of the three categories of planars
|Size of Memory Card||16 MHz||20 MHz||25 MHz|
|1 MB||OK||OK||NOT OK - 225|
|2 MB||OK||OK||NOT OK - 225|
|4 MB||2 MB useable||OK||OK|
Note 1: 225 is the POST Error Code resulting from having memory that is too slow.
Note 2: On some 20 MHz planars with 4 MB memory cards on the planar, the IBM diagnostics will occasionally fail, but the memory will still function OK. With the PIICEON 4 MB (70ns.) memory card the IBM diagnostics may also fail. However, both the IBM and PIICEON 4 MB memory cards will function properly and they do pass the Norton Utilities memory diagnostics without any problems. I will be doing more investigation regarding this.