Grazie mille Fabio ! Actually, I wired all addresses of my 2732 to the bus, so I guessed I do not need a pull down... I removed the A10/A11 decoding on the 74138 (U28) as these lines are now connected to the EPROM. The 2732 is fully accessible, to validate that, I set the 2732 at F000 and burned a code from F000 to FFFF finishing with a HALT, and this is how I realized to power on jump to F000 works only 1/2 of the times. I realized the 74138 enables the EPROM sometimes upon reset meaning this probably happens when the address bus is in tri-state so I will probably have to tie down the address lines. I will work on the docs you kindly sent me and keep you updated. Ciao, Philippe
Le mercredi 18 juin 2014 23:12:42 UTC+2, Fabio Battaglia a écrit : > > Hi Philippe! > I'm traveling right now so can't give you a long, detailed answer. > > My board was not 2732 compliant: I had to mod it. Actually, you can fit a > 2716... If you use a 2732 remember to pull down the remaining address lines > or replicate the monitor code inside the EPROM! Otherwise you'll get > erratic behaviour at reset and during work. > > I'll send you the schematics and the manual (which includes the EPROM mod > instructions) and a revision changelog. > I have yet to ask John King from soundfarm (who kindly sent these docs to > me to help) if I can publish them, that's why I'm not pasting them here. > > Fabio > >> Hi Fabio, >> > I have the same card but a V1.03 that I got on eBay, worked OK with the > original 2708. I noticed though that some mods were done on the board. As I > could not read or write the 2708 with my EPROM programmer I decided to > replace it by a 2732 and modified the board accordingly. When PROMing a > simple program including HALT at the end, I noticed the jump-on-reset to my > EPROM is working approx 1/3 times... I think I narrowed this down to the > SET input of the 7474 that is used to tri-state the buffers until the Z80 > reached the EPROM address. Surprisingly, it triggers while the address bus > is still in tri-state, so I was wondering if I need to put some pull-down > resistors on the address bus, or check the reset timing..? > Did you make some modifications to have your card work with a 2732 (or is > your version already compliant with it ?). Did you experience any issue > with the jump-on-reset circuitry ? > If you could send me the schematics of your board that would be great as I > am sure some bugs from V1.03 were corrected in your version.. > thanks in advance for your feedback ! > philippe > > -- > 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 [email protected] <javascript:>. > For more options, visit https://groups.google.com/d/optout. > -- 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 [email protected]. For more options, visit https://groups.google.com/d/optout.
