Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!sdd.hp.com!hp-pcd!hplsla!tomb From: tomb@hplsla.HP.COM (Tom Bruhns) Newsgroups: comp.sys.amiga.hardware Subject: Re: Why ground pals in A1000 ? Message-ID: <11260006@hplsla.HP.COM> Date: 24 Apr 91 18:53:28 GMT References: Organization: HP Lake Stevens, WA Lines: 24 root@apal.hanse.de (Andreas Mueller) writes: >I often read about 'grounding Pals in the A1000'. > >How, why and where (which A1000 rev.) is this done ? > >What kind of Pals are used in the A1000 (I've a Pal A1000 with the Kickstart >mem on the mainboard) The PALs (Programmable Array Logic [chips]) are used for, I believe, some address decoding and perhaps some other simple things. Not to be confused with PAL (a television standard that specifies things like scan frequencies and color encoding; see also SECAM and NTSC, other different standards). The PALs are on the daughter board in an A1000, and the ground between the daughter board and the mother board in the unmodified A1000 has shown itself to be marginal, particularly when peripherals are added to the expansion bus. "Grounding the PALs" refers to adding wires from the PAL ground pins to a good ground point on the mother board. I did this with two pieces of braid from RG-58/U coax cable on my A1000 and saw some improvement, both on a 'scope probing 'ground' and in ability to operate without errors with memory added externally. I understand that it also helps to change the PALs to logically equivalent but faster or lower power or 'cleaner' PALs. I haven't needed to do that...