Yes all correct Dave, thanks
John Monahan Ph.D
From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of yoda
Been working through your notes and found a couple errors I think.
I have free running working great
I am working through the DTACK and WAIT state circuit - 3rd paragraph where you are looking at signals on U40 (BTW I only have 74ls367 and it seems to work so far) I think you mean 7 is high and 9,11 and 13 will pules (not 79)
but for this to happen I think you need to have U42 in plugged in as well. You do have it plugged in on your picture but don't mention to add it. If you don't then pin 7 will pulse.
Further down though I am not there you on the Watchdog time in first paragraph you say insert JP9 that should be J9 instead.
I am probably going to call it a night soon but it looks like things are working so far.
Hi John - read through what you have updated so far looks good and I will be starting now. BTW you probably should update your web site to say V3 instead of V2 as on Andrew's site it is referred to as V3 and technically it is the third version if you count the Wilcox board as V1.
Thanks for the explanations - they make sense. Might want to publish what you have - more eyes could be helpful. I am ready to start populating - want to do some voltage checks, and clock - then will start populating enough to do the NOP tests - then I next plan to do the Character out loop with no memory to get that working then populate the memory and use the memory checking code that does not use a stack (all inline code) to make sure the on board ram is working then start branching out to check off board memory. I assume those are similar to the steps you have done.
Dave I am in the middle of bringing my board up. I have so far step by step assembly notes for everybody with tests at each step. I am bringing it up as a bus master first. Have monitor and onboard RAM working fine but for some reason all bus RAM is showing up as FF’s. Currently debugging!
There are a lot of jumpers each of which will require a detailed explanation. I’m am trying to get it debugged/ written up before others start into it so excuse the quick reply.
All the K’s have to do with master/slave switching. For a simple master, XFERI & XFERII just go to ground, K4 2-3 (slight bug, to have 68K LED active bend out pin 1 of U71 and wire wrap 1,2 & 3 together). JP13 is a carryover from the original Wilcox board and is basically now just a connection point in case one wants to hookup a external single step circuit as he had originally. Yes always closed.
See below for others
From: n8ve...@googlegroups.com [mailto:n8ve...@googlegroups.com] On Behalf Of yoda
I have some questions on the jumpers. I am not quite sure what the settings should be for K1, K2, and K4 as they are new and probably have something to do with the TMA stuff. Also it seems that JP13 must always be Closed or I don't understand the function of it.
Here is what I have come up with so far - I am going to start using as a bus master with no SMB currently in the system I have labeled some with ? Could you clarify or confirm them? Thanks
J9 Open Watch Dog Timer ------- Closed
J10 Closed Auto Vector enabled
J13 Open Enable Various Interrupts
J14 1-3, 2-4 ROM at XX8000
J15 Closed Enable Boot Feature
JB1 1-2, 3-4 Values for 28C256 eeprom
JB2 3-4, 7-8 Values for 62256 memory
JP1 Open OV_A
JP2 Open OV_B
JP3 Open OV_C
Do not add this circuit until later, it’s for DMA in slave mode will explain later.
JP4 1-2 Connect to SDSB*
JP5 Open S100 pin 65
Only if these signals are not generated by front panel or our SMB
JP6 1-2 Bus_RESET*
JP7 1-2 HOLD*
JP8 1-2 SLAVE_CLR*
JP9 1-2 POC*
JP10 1-2 BUS_RESET*
JP11 1-2 MWRT*
JP12 1-2 Clock*
JP13 1-2 ???? seems this needs to be always connected see above
Do not add this circuit until later it’s for DMA in slave mode will explain later.
JP14 Open BR* ???????
JP15 1-2 PHLDA*
JP16 Open S100 pin 66
These are fine
K1 1-3 XFERI ?????
K2 3-4 XFERII ?????
K3 1-2 NMI*
K4 2-3 XFERII
K5 2-3 DODSB*
K6 2-3 HALT
K7 2-3 bA20 ------- 1-2
P2 dependent Sets number of Wait States
The whole U2,U3 cascade is for handshaking on master to slave transition and DMA designation
In master mode this whole circuit can be ignored
P5 1-2 TMAXPU* ?????
P6 1-2, 5-6 Passes Master Reset through ???? For master P6 1-3 and 5-6 check pins carefully