We should probably keep a "to do list" for V2 Josh. 1. Add MWRT with jumper. 2. For I/O port data out, address lines A8-A15 should be pulled low. (so only ports 0-255 addressed). 3. Address lines A16 to A23 always pulled low (in "master" mode)
Space is tight on the board as it is. #2 & #3 will require 74LS244's. You can shave off some space for the SD card transistor etc. As best I can tell E2 pin 10 does not do anything. On Wednesday, July 30, 2014 5:24:51 PM UTC-7, Crustyomo wrote: > John, > > Thank you for testing this out and getting it working. I'm not having the > same pull up problem on sOUT. > > This board was designed for use with the ALTAIR and IMSAI FP boards, but I > agree and in V2, I will add mWRT generation and jumper select it for the > flexibility. > > You are right about the high address bus. The 8080A places the I/O > address on both the upper and lower 8 bits. On my initial version, I was > decoding the upper 8 bits for use with I/O and Memory banks, but later > changed to add it's own decoder chip on the lower address to support Z80 > CPU's that might want to access this card as a peripheral. > > What should I do with those upper address lines? Should I just ground > them? or pull them high/low through a resistor network? > Something for V2. > > Thanks for the schematic corrections, I have updated my copy and will > release another revision soon. > > I should also point out, if anyone is wanting to use the 16550 UART chip, > then RP2 must be changed to 47K. Thanks to testing with Fabio, he found > that the 16550 data bus output is getting pulled marginally high with a > 4.7K. The 47K will suffice to prevent the bus from floating yet not > interfere with the 16550's. > > Cheers, > Josh > > > > ------------------------------ > From: [email protected] <javascript:> > To: [email protected] <javascript:> > CC: [email protected] <javascript:> > Subject: [N8VEM-S100:4755] Progress with the 8080 board > Date: Wed, 30 Jul 2014 11:44:12 -0700 > > Hi Josh solved the I/O problem (see below). Since a few others may be in > the board assembly stage I thought I would write up my progress so far for > the group! > > > > I am running the board in my “test box” that has no front panel. Just > the V2-SMB and Propeller Console I/O. I always start with a minimal system > so I don’t “blow out” board drivers etc. > > > > First one needs to remember that unlike the Z80, the 8080 does not treat > the upper 8 bits of an I/O port the same way. On our Z80 board (and most > others) the upper 8 bits are set ort Zero. Not so on this board. So on all > the N8VEM/S100Computers boards (and perhaps others), ports need to be > jumpered so that only the lower 8 bits are factored into port addressing. > All our boards have this option. Not a nice solution since with 16 bit > CPUs the ports appear on every 256 byte boundary. Setting the jumper K3 to > 2-3 on the V2-SMB allowed the routine below to work correctly. > > > > The IEEE-696 upper address lines float. This will not allow 696 RAM > boards to work unless they are adjusted. Our N8VEM/S100Computers boards > generally have a jumper to ignore these lines but again will not work with > 16 bit CPU’s. Our V2-SMB has an option to force these address lines to > ground when this board is the master but release them for slave/16 bit > CPU’s. > > > > Second the board does not generate the S100 MWRT signal. (On front panel > systems, it’s generated there). One can be generated on the SMB with the > JP11 jumper. > > > > There seems to be a problem with the sOUT signal (s100 Pin 45) on J8. > It’s been pulled high all the time – at least on my board. I bent out J8 > pin 6 and connected it directly to the S100 bus (bending out the pin > connection on the extender board). I will try and follow traces to figure > what is going on here. > > > > Minor schematic errors. > > Pins 8 & 9 of E2 are switched. > > Pins 1 & 19 of I8 and H8 should be labeled D-IN, D-OUT, etc. > > > > Still a work in progress, but wanted to save others reinventing the wheel. > > > > > > John > > > > > > > > *From:* John Monahan [mailto:[email protected] <javascript:>] > *Sent:* Tuesday, July 29, 2014 7:21 PM > *To:* 'Crusty OMO' > *Subject:* Problem with sOUT with the 8080 board > > > > Hi Josh. > > I running into a bit of a problem with the 8080 board. I use this code > > > > BEGIN:0009 3E34 MVI A,'4' ;FOR QUICK HARDWARE > DIAGNOSTIC TEST > > 000B D301 OUT 01H > > 000D DBEF IN IOBYTE > > 000F D301 OUT 01H > > 0011 C30900 JMP BEGIN > > > > I can get a “4” on the screen no problem. But I found no matter what > value I have the dip switches for port EF I get a blank on the screen. > > With the SMB switches set to 33H one normally see “3’s” > > > > Analysis tracked things down to the fact that sOUT was not being generated > on the bus. The LED on the SMB in fact did not flicker. > > I bent out pin 6 of J8 and bent out the edge connector pin going to the > bus and jumpered J8 pin 6 to the S100 line #45. Now sOUT flickers (as it > should). I find that pin 45 on the board is being pulled high (and warming > up the J8 IC). Before I dig further, wanted to know if you see this. > > > > For configuration.. > > SMB, Propeller Console I/O board (Ports 0 & 1) and the 8080 board nothing > else in bus. > > Note have to generate MWRT on SMB - J11, need to tell people this as it’s > not generated on your board if no FP. > > I have JP8 LHS jumper open the other 7 closed > > JP9 LHS jumper closed all the rest open. > > So 8K ROM at 0, the rest RAM > > No R15 jumpers so all I/O ports via bus > > JP4 1-2, JP1 2-3, JP6 2-3, JP7 1-2 > > > > No A5 ,A6 , J5 or J3 (but J7 is present). > > > > John > > > > 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] <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. 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