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The S-100 Bus FPGA Z80 SBC Board Page 2.
   Final Board
Introduction
This section is devoted to adding further improvements, changes etc. to the board.  It assumes by now you have a fully functional board and a general understanding of its components and FPGA programming.  Consequently the descriptions will be a little more brief and to the point. 
If other users would like to contribute FPGA code I will be pleased to present them here.

 Increasing the FPGA ROM to 16K.
Up until now we have been running the Z80 monitor within a 4 K boundary from F000H to FFFFH with two 4K pages either of which can be switched in or out.  This has allow us to have a fairly extensive basic Z80 monitor and a separate menu driven 4K section to access the IDE/CF card interface. It would be nice to have a similar menu for the SD card interface.   There is not enough room in 8K to fit all this.  The solution is to increase the FPGA ROM module to 16K and have up to four 4K pages.  The paging process is exactly the same as for the 2 page 8K ROM except now we adjust the address lines A12 and A13.  At the moment I'm only using three 4K pages:-

 Page #0   A12 Low,  A13 Low    Output to Port 07H 00H    Contains basic Z80 Monitor                   SBC_MONA.Z80
Page #1   A12 High, A13 Low    Output to Port 07H 01H    Contains IDE menu and routines            SBC_MONB.Z80
Page #3   A12 Low,  A13 High   Output to Port 07H 04H    Contains SD Card menu and routines.     SBC_MONC.Z80

Remember the only link between the 4K pages is the jumps at the start of each module.  You cannot call one routine from one section to another. 

The changes within the FPGA code is trivial.  We just change the 8K ROM in the "ROM & RAM Interface" to a 16K ROM.  We add in one more address line (A13).
The trick however is building and loading up the .HEX file for Quartus.  
As before we load up the Wellon Programmer IDE.  This time we place the 4K modules at 0000H, 1000H and 2000H.
Hopefully these pictures are enough to explain the process.
    16K hex File Load
Remember to point the Quartus ROM dialog box (when asked) to the correct location of the SBC-MON2_4+4K+4K.HEX file.  If you don't alter the file you don't have to reload the .HEX file each time before a Quartus compile. The SBC-MON2_4+4K+4K.HEX is available at the bottom of this page.

The relevant Quartus .bdf file "upgrade" is Z80_FPGA17.bdf.  See the .zip file below

Here is a picture of the Z80 monitor with the 3 menus.
   
    Three page menu

With 16K there is ample room to improve the above Z80 monitor!

SBC-MON2_16K.Zip                              (This .zip file contains the Z80 monitor and FPGA .HEX files)       (V1.1  9/4/2019)  
SBC-MON2_4+4K+4K.HEX                    (This .HEX file contains the file for the 16K Quartus ROM)       (V1.1  9/4/2019)  
Z80_FPGA17 -- (16K Rom Added)           (V1.1  9/7/2019)  

More additions later!

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This page was last modified on 05/20/2020