The first 8 locations of map ram memory are used. Two data patterns of Number 0000 and Number ffff(hex) are also used. 4) Map Ram Content Test - This test writes and reads the entire 256 locations of map ram, using two data patterns (Number 0000 and Number ffff) to check for a short circuit to ground or +5 Volt. 5) Main Ram Data Lines Test - The test sends a single "1" bit across the data lines to check for a short circuit among the data lines. 6) Main Ram Address Lines Test - This test sends data across the address lines of main memory to check for a short circuit among the address lines. The first eight locations of main ram memory are used.
Two data patterns of Number 0000 and Number ffff (hex) are also used. 6.1) Small-Block of Main Memory Test - The first 4K bytes of memory and locations Ifffc to Iffff are written with data value of 0's and check for memory integrities. These areas are used as a communication block to awake the Z80 to print out a sign-on message through its port number 1. 7) Parallel Port (8255) Test - Two patterns of 0000 and ffff (hex) are written/read back to verify all three ports on 8255.
8) Z80 Initialization Test - First, the Z80 parameter block is set up with its pointer in memory location Ifffc (a designated area for Z80 communication), then generates a channel attention to awakening the Z80 controller. The Z80 returns its firmware version number in the first word of the Z80 parameter block. If this operation is successful, the Z80's ability to accept initialization command from host CPU is tested. The time-out loop will be set up if Z80 fails to clear the command pending flag. 9) Z80 Channel Test - Attempts to send a "Channel Initialization" command to Z80's port number 1 after all the required parameters are set up in the Z80's channel control block.
If successful, a wake-up bell and sign-on message will be sent to the Z80's port number 1. This will serve as a wake-up call and to verify the Z80's port number 1 interface. 6-2'