that rex does not work. I will pull it down. it was for visibility only..
On Thu, Jun 16, 2016 at 11:26 AM, Brian White <[email protected]> wrote: > Crap I'm sorry Mike! > > But the question was about an option rom not the main rom. A dip28 chip just > about fills all available volume in the option rom socket. If you need to > add anything else to the board, it will be difficult. There is a little room > on the edge, and there is about 1/10" of height across the bottom. Can you > make a 27C256 both usable and re-programmable within those constraints? > Would it need a jumper and resistor like 28C256 does? > > As for rex, now that Stephen has put a version of rex up on osh park I plan > to try to build one and we'll see. I've already ordered a set. > > If it costs more in parts, that's a potential reason. > > If it's more difficult to build, then that is a potential reason. It was > easy to do the soic option rom, and the through-hole plcc socket main rom, > and your own dip28 main rom. The qfp legs are finer than soic, but still > look doable, but that tsop chip...well we'll see, maybe it's fine. > > If it requires special software or hardware to program the cpld, that is a > protential reason. I can program an eprom using small purely open source > software and $30 hardware. For the fpga in the MISE, I got a ByteBlaster for > $25 and the programming software was free, but it was a large download of > proprietary software, and was not easy to get working on the linux netbook I > like to use for stuff like this where possible. I don't know yet what it > takes to program the cpld on the rex, but I'm guessing it will be doable and > within reason like those examples. > > If there is any software incompatibility, that is a potential reason. > > If it conflicts with the option rom socket, then that is a potential reason. > > On Jun 15, 2016 10:41 PM, "Mike Stein" <[email protected]> wrote: > > So it's become *Stephen's* M100ROM board now? ;-) > > I don't see any reason myself why you couldn't make a re-programmable Option > ROM adapter using a 27C256 EPROM but I'm not going to get into another > discussion; I am curious though why, with the various other options > including REX, you'd want one? > > Personally, I still think an Option ROM adapter using a RAM chip would be > nice; I wonder if the FigTronix one could be adapted... > > m > > ----- Original Message ----- > From: Kurt McCullum > To: Model 100 Discussion > Sent: Tuesday, June 14, 2016 2:30 PM > Subject: Re: [M100] Adapter Board > > Thanks for all the information. The list is once again a wealth of > knowledge. I'll look into the other boards. > > Kurt > > > On Tuesday, June 14, 2016 10:18 AM, Brian White <[email protected]> wrote: > > > A 27C256 is problematical in the option rom socket because you can't > reprogram it once you solder it. Or at least it would be pretty hard to > squeeze the couple extra components to handle the Vpp pin so that it is tied > to Vcc (or gdn or no-connect, I forget what it needs right now, other than > that it should *not* be connected to any of the socket legs) during normal > run-time operation, but not tied to Vcc and instead *is* routed to an edge > contact for programming. The 28C256 board can do it because the chip is SOIC > package and there is physically room for the parts. > There is no such thing as a SOIC 27C256, or at least not an erasable one. > Burning and soldering a chip as a one-way trip is not really hobbyist > friendly. You risk wasting $6 chips and having to de-solder, clean, and > resolder chips on the board for every mistake or testing another rom. > It's different if you're producing 100 copies of the same thing to sell. You > don't care about re-writing then. But in that case you have the resources to > just whip up your own new board any time you want. A few different similar > board designs are public that you can download and copy, and even the cad > software is free (kicad). Edit and upload to osh park and order as set for > $6. > But I suggest just use the SOIC v2.0 28C256 board. And get the option rom > programming adapter v2 at the same time. And some singlenrow machined round > pin headers for the programming adapter. > Or use the m100 board (Stephen's, not FigTroniX) and use the option rom > feature on that. It goes in the main rom socket inside, not in the option > rom socket, and it can provide both a main and option rom in one uv-erasable > 28 pin dip 27C512. > -- > bkw > On Jun 14, 2016 11:42 AM, "Stephen Adolph" <[email protected]> wrote: > > ah sorry I missed that. yah it is for main rom socket. not optrom. > but it can provide optrom. > > On Tue, Jun 14, 2016 at 11:35 AM, Kurt McCullum <[email protected]> > wrote: >> Would it just need to be cut down to fit into a 102 or 200 optrom slot? I >> suppose since the 200 has a regular socket for its main ROM it might work >> as >> is. >> >> >> >> On Tuesday, June 14, 2016 8:20 AM, Stephen Adolph <[email protected]> >> wrote: >> >> >> the M100ROM board supports 27C256.. >> >> On Tue, Jun 14, 2016 at 10:58 AM, Kurt McCullum <[email protected]> >> wrote: >>> There have been a few new adapter boards for the OptRom slot of the >>> 100/102/200. I notice that none of them support a standard 27C256 EPROM. >>> I >>> know these boards used to be available, along with the wrap around >>> flexible >>> circuit boards used by Traveling Software. Does anybody know of an >>> OSHPark >>> design that exists? >>> >>> Kurt >> >> > > >
