GUBBINS@RADC-TOPS20.ARPA (Gern) (01/05/89)
I have a couple of friends that would be interested in the Z-205s, in a working, non-FBE condition, with RAM (64K chips) for $150ish or $125ish with no RAM. I and others do not at all approve of the FBE Z-205 method of removing the MB RAM, when it is so unnecessary. I have 768K on MB, and 256K RAMDISK on the Z-205 card (will go to 1MB when 256K chip prices come back down). I've talked to FBE about how dumb his method is and told him the simple/straight alternative method and he agreed, he just hadn't thought of it and how simple it was. Using the PUP MDISK.ASM modified to recover after warm boot, with support for lots of neat stuff (like a RAMDISK Access LED, etc), it has been modified to support "Overstuffed" RAM: The Normal Unmodified Z-205 256K card is addressed starting at 768K, the RAMDISK driver PHANTOMs out the 192K of Video RAM also starting at 768K and at the critical time, turns off the System ROM in the top 32K of the 1MB address space, making all 256K of the card usable for the RAMDISK. Support is included for an optional mod to the card by tack soldering 2 small wires on it to turn the card "Off" when not being used by the RAMDISK. This yeilds a 768K System RAM machine, RAMLIM.COM no longer must be used, CP/M-86, CCP/M-86, and MP/M that load in the highest available address will now boot, the RAMDISK is protected from accidental trashing (the RAM is offline from the CPU, the Video and System ROM are in the address space as normal). By connecting all the #1 pins of the RAM ICs together, and a couple of other small wires tack soldered to the back, 256K RAM ICs can be used and the Control port is enhanced to bank switch between the 4 banks of 256K for 1MByte of RAMDISK on the Z-205 card with unaffected 768K on the motherboard (no 512K on the MB or other MB Mucking as required by the FBE Kit). Simple. Now I just have to wait for the 256K IC prices to drop for me to try it (Rob Logan at Clarkson did this years ago). Cheers, Gern -------