Thanks John, This clears up the patching issue pretty well. While I'm at it, I'd like to ask you additional advice: Next week I should receive the last components I need to complete my S-100 backplane and I'll have to decide with which board I'll start my computer. The very first one will be the bus extender, as there is not much that can go wrong with that one, but as for the next I have the following choices:
1) 6502 CPU Board V1 (Master only) 2) Z80 V2 board 3) EPROM/RAM board V1 (I want to start using it as an 1Mb SRAM board) 4) Serial I/O V1 While rather limited, I'm considering the 6502 board because it has a limited component count and I can try it in free-running mode without any other board in the system. I'd welcome an expert's advice though :-) Also, I'm searching around for a card cage, but haven't been able to find one anywhere... Pointers on that? Thanks again, Fabio On Sunday, February 9, 2014 7:32:40 PM UTC+1, monahanz wrote: > > Hi Fabio, > > First the error/patch is really only relevant for very large seldom used > (1MX8 EPROMS). None of the common 24 or 28 pin EPROMS/EEPROMS are > affected. The U100 & U101 RAM/Flash ROM section is fine and should not be > changed. > > The cut should be as near as possible to pin 1 of U4 (front of board). > This is joined to pin 1 of U121. The connection from U121 pin 1 onwards to > K23 & K26 should be cut (front of board) and a jumper to pin1 of K23/K26 > connected to U8 pin 7. > > Pin 1 of U4/U121 should be then be connected to bA19. > > > > Good luck with your build > > John > > > > > > *From:* [email protected] <javascript:> [mailto: > [email protected] <javascript:>] *On Behalf Of *Fabio Battaglia > *Sent:* Sunday, February 9, 2014 2:18 AM > *To:* [email protected] <javascript:> > *Subject:* [N8VEM-S100:2378] Patching the S-100 PROM/SRAM Board V1 > > > > Hello group, > I'm approaching the stage where I'm ready to build my first S100 boards, > and I'm reading up the documentation for each board on S100Computers.com > before start soldering anything. > There is something which isn't completely clear to me about the PROM/SRAM > board described at > this<http://s100computers.com/My%20System%20Pages/PROM%20Board/PROM%20Board.htm>page > (I have a V1, the schematics are numbered V2-2). > > At the bottom I read that the board has pin 1 of U4 and U121 miswired to > bA18 instead of bA19 (U8 pin 9), and that I should cut the trace and rewire > it correctly. > > I'm checking the board, and I see the following: > From U8 pin 7 (bA18) starts a single trace which branches through a via > and goes to U11 pin 5, while the other branch goes to U4 pin 1, U121 pin 1 > and headers K23 pin 1 and K26 pin 1. > > The question is, do I have to > 1) Wire only U121 and U4 pin 1 to bA19 and keep K23 and K26 wired to bA18, > or > 2) cut off the second branch entirely (U121, U4, K23 and K26) and wire > everything to bA19? > I guess it's the first one, which involves two cuts and two wires (a cut > after the branch and a rewire to bA19, another cut after U121, before K23 > and a rewire to bA18) but I want to be sure before doing any damage. > > I hope I have explained myself well enough, If not, tell me and I'll try > again. > > Thanks, > Fabio > > -- > 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/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 [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
