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A 74S288 ROM chip can also be used... if the pins match?
> From: mon...@vitasoft.org > To: n8vem...@googlegroups.com > Subject: RE: [N8VEM-S100:2645] Re: A new (V2) version of the S100 Bus System Support Board > Date: Tue, 4 Mar 2014 12:20:20 -0800 > > One more note on this. I had actually considered doing a small GAL Hex to 7 > bit converter (GAL22V10), (the old DM9368 are no longer available), but > again you really cannot multiplex it fast enough -- so you would need 10 of > them. Could be on a (larger) mezzanine board but at $3 each (Jameco) and a > new mezzanine layout board etc. I figure it's not worth it. Utsource > (http://www.utsource.net/ic-datasheet/TIL311-421656.html) sells TIL's at > ~$9. > John > > > > -----Original Message----- > From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On > Behalf Of David Riley > Sent: Monday, March 3, 2014 7:37 PM > To: n8vem...@googlegroups.com > Subject: Re: [N8VEM-S100:2635] Re: A new (V2) version of the S100 Bus System > Support Board > > On Mar 3, 2014, at 21:48, Andrew Bingham <ab...@gmail.com> wrote: > > > > I think the big problem is as John mentioned you need to grab the data > from the address and data buses and output it to the LCD fast enough to > complete the update before the next clock cycle. > > > > Say you're talking about a 24-bit address and 16-bit data, in hex that is > 10 characters. The part of the system talking to the LCD would have to > update it at 120 Mhz in order to be able to update all 10 characters before > the next clock cycle (and that's assuming that you can update 1 full > character/clock). Most microcontrollers won't be up to that task. > > That's assuming you want to update it at the bus rate. An LCD can't possibly > keep up with even a fraction of that, not could the human eye. You could, > however, do something along the lines of a 60 Hz update cycle, which is much > more achievable. > > Personally, I like the aesthetics of an LED display better, and the fact > that it's updating with the bus gives you an idea of how often it's showing > segments (something you won't get with an LCD). > > > For replacing the TIL311 displays, I have seen reference to DIP decoder > chips that will decode 4 bits of binary into showing hex on standard > 7-segment displays - 0-9 and A, lower case b, C, lowercase d, E, F. That's > probably the best option for something that will remain readily > available.... Or program a DIP PLD device. > > There are certainly lots of hardware decoding devices meant for 7-segment > LEDs (and you can make one with a simple CPLD rather easily). TIL311 style > devices are becoming more rare, but I think they're certainly the best > looking ones out there (short of Nixie tubes, I guess, but that's bordering > on silly). > > > - Dave > > -- > You received this message because you are subscribed to the Google Groups > "N8VEM-S100" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to n8vem-s100+...@googlegroups.com. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- > You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. > To unsubscribe from this group and stop receiving emails from it, send an email to n8vem-s100+...@googlegroups.com. > For more options, visit https://groups.google.com/groups/opt_out. |