wombat@claris.com (Scott Lindsey) (02/17/90)
In article <10757.infoapple.net@pro-generic> sysop@pro-generic.cts.com (Matthew Montano) writes: > A brand new ROM3 //gs was recieved by a friend of mine who runs a small > dealership in Oakville, ON. When he recieved it, he opened it up to install > the TWGS, Sonic Blaster and SCSI card.. and he noticed something, well.. > weird. > There is now a 28.63630Mhz crystal on the motherboard. I have a 28mhz crystal > on my TransWarp GS at home... Did it actually say that on the motherboard? Mine says "3.686400 MHZ" and the actual crystal says "NYMPH 197-00208 88-28", but it's also a beta machine. Scott Lindsey | I dig iguana in their outer space duds Claris Corp. | saying, "Aren't you glad we only eat bugs?" ames!claris!wombat| DISCLAIMER: These are not the opinions of Claris, Apple, wombat@claris.com | StyleWare, the author, or anyone else living or Dead.
wack@udel.edu (Andrew Wack) (02/19/90)
In article <WOMBAT.90Feb16104819@claris.com> wombat@claris.com (Scott Lindsey) writes: >In article <10757.infoapple.net@pro-generic> sysop@pro-generic.cts.com (Matthew Montano) writes: > >> A brand new ROM3 //gs was recieved by a friend of mine who runs a small >> dealership in Oakville, ON. When he recieved it, he opened it up to install >> the TWGS, Sonic Blaster and SCSI card.. and he noticed something, well.. >> weird. > >> There is now a 28.63630Mhz crystal on the motherboard. I have a 28mhz crystal >> on my TransWarp GS at home... > >Did it actually say that on the motherboard? Mine says "3.686400 MHZ" and >the actual crystal says "NYMPH 197-00208 88-28", but it's also a beta machine. > Don't get too excited. My Woz edition gs also has a 28.63630 crystal on the motherboard. It is also in the schematic in the hardware reference. That frequency is used and subdivided to provide all the timing (including video) on the gs. An apple ][, ][+, //e all have 14.318... crystals, but they still only run at 1 Mhz!! -- -------------------------------------------------------------------------------- Andrew Wack Gravitation cannot be held responsible Internet : wack@udel.edu for people falling in love -- Albert Einstein
henrym@pro-europa.cts.com (Henry Malmgren) (02/20/90)
In-Reply-To: message from wombat@claris.com >There is now a 28.63630Mhz crystal on the motherboard. I have a 28mhz >Crystal on my TransWarp GS at home... Scott Lindsey replied: >Did it actually say that on the motherboard? Mine says "3.686400 MHZ" and >the actual crystal says "NYMPH 197-00208 88-28", but it's also a beta machine. Scott, my final version also has the exact same crystal. I don't see any way that the Rom 03 machine could be easily upgraded into a Rom 4, contrary to some rumers around here. UUCP: crash!pro-europa!henrym ARPA: crash!pro-europa!henrym@nosc.mil INET: henrym@pro-europa.cts.com America Online: Henrym9
toddpw@tybalt.caltech.edu (Todd P. Whitesel) (02/21/90)
henrym@pro-europa.cts.com (Henry Malmgren) writes: >In-Reply-To: message from wombat@claris.com >>There is now a 28.63630Mhz crystal on the motherboard. I have a 28mhz >>Crystal on my TransWarp GS at home... >Scott Lindsey replied: >>Did it actually say that on the motherboard? Mine says "3.686400 MHZ" and >>the actual crystal says "NYMPH 197-00208 88-28", but it's also a beta >machine. The 3.6864 Mhz crystal is used by the 8530 to generate baud rates for the serial port. This crystal is hooked directly to the serial chip and is used for no other purpose. All //gs's have a 28.63636 Mhz crystal in them (it's underneath the power supply so you don't normally see it) which is only required by the bizarre display hacks employed by the VGC for super hires. The VGC also divides the 28M signal in half to produce a 14.31818 Mhz clock which is then used by the rest of the machine. 14.31818 Mhz is also the main time base of every 8 bit Apple //, for the simple reason that if you divide 14.31818 by four you get 3.579545 Mhz, which is the reference frequency used by composite video and color television. Your Transwarp GS has a perfect 28.0000 Mhz crystal (usually) which is divided by two (twice) to generate the 7 Mhz CPU clock. They could have used a 14 Mhz crystal and divided it by two, but they probably found a way to make the cache circuitry simpler by doubling the clock frequency and using the extra states. As a side note, the Apple //c+ has three crystals in it as opposed to two in the //gs: 14.31818, to generate the video timing; 1.8432 Mhz, to generate the serial port baud rates; and 16.0 Mhz, which is used by the cache controller to run the 65c02 at 4 Mhz. I hope this clarifies things a bit. Todd Whitesel toddpw @ tybalt.caltech.edu