CPLD prototype board #5 for RC2014
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Bill Shen
Nov 11, 2020, 11:03:21 AM11/11/20
to retro-comp
An treasure hunt expedition in my overflowing garage found trays of EPM7192SQC160. Some are new but many are used parts with unknown functionalities. This calls for a prototype board. If they work, EPM7192S contains sufficient logic fabric to make pretty decent logic analyzer and video display. Another board out to JLCPCB.
Bill
Greg Holdren
Nov 11, 2020, 1:23:52 PM11/11/20
to retro-comp
Bill,
Nice board. I like CPLD/FPGA boards. So much to do with them.
Looks like there was room to place TH access for the extra pins not used. :)
Greg
Bill Shen
Nov 23, 2020, 12:08:57 AM11/23/20
to retro-comp
It seems I'm having problems with library footprint; the pads for the 160 pin QFP is slightly off, but I'm able to adjust the pins to fit. Other than that, the board is working and the used EPM7192S is good; successfully program it to emulate a serial port. Hooray, a bigger sandbox to play in!
Bill
Bill
Bill Shen
Jan 5, 2021, 12:21:40 PM1/5/21
to retro-comp
I'm over the 6502.org last month making a 6502 SBC based on the rev5 prototype board. The theme is "salvage computing, building a retro computer with unknown parts acquired over eBay". (http://forum.6502.org/viewtopic.php?f=10&t=6421 ) The design has reached a stable point right now, so I thought I'll show what I've done using the rev5 prototype board.
For lack of better name it is called Proto65. Conceptually it is like ZRCC where a small bootstrap ROM in CPLD provides the ability to test the unknown CPU first and then boot it up through the serial port and then IDE port. This evolving process was applied to the 6502 eBay parts. These parts are functional but not able to run beyond 3.68MHz, so I did eventually acquired 14MHz W65C02 from Mouser and run Proto65 at 14.7MHz. I also added a I2C interface and able to port Conway's Life to it. Running Conway's Life I've found that 6502 at 14.7MHz is about 20% faster than Z80 at 22MHz and this is with me as newbie 6502 programmer.
I have documented the design and software here:
https://www.retrobrewcomputers.org/doku.php?id=builderpages:plasmo:protor5:proto65:proto65r02
EPM7192S is way bigger than needed for current design; a EPM7128S or even EPM7064S probably can do everything I've done, but it sure is nice to have the extra capacities to add diagnostic functions to troubleshoot hardware. I also want to add VGA and keyboard next step so that will definitely need the larger CPLD.
I'm encouraged by this experience to think about a full-featured common baseboard with video, keyboard, hard disk, mass storage, serial port, I2C, and expansion bus. This common baseboard can support a varieties of 8-bit and some 16-bit 5-volt processors. Conceptually it is like G8PP, but it is a standalone platform with its own keyboard and video. It will be a nice platform to experimenting with the many processors I have in my part bins.
Bill
For lack of better name it is called Proto65. Conceptually it is like ZRCC where a small bootstrap ROM in CPLD provides the ability to test the unknown CPU first and then boot it up through the serial port and then IDE port. This evolving process was applied to the 6502 eBay parts. These parts are functional but not able to run beyond 3.68MHz, so I did eventually acquired 14MHz W65C02 from Mouser and run Proto65 at 14.7MHz. I also added a I2C interface and able to port Conway's Life to it. Running Conway's Life I've found that 6502 at 14.7MHz is about 20% faster than Z80 at 22MHz and this is with me as newbie 6502 programmer.
I have documented the design and software here:
https://www.retrobrewcomputers.org/doku.php?id=builderpages:plasmo:protor5:proto65:proto65r02
EPM7192S is way bigger than needed for current design; a EPM7128S or even EPM7064S probably can do everything I've done, but it sure is nice to have the extra capacities to add diagnostic functions to troubleshoot hardware. I also want to add VGA and keyboard next step so that will definitely need the larger CPLD.
I'm encouraged by this experience to think about a full-featured common baseboard with video, keyboard, hard disk, mass storage, serial port, I2C, and expansion bus. This common baseboard can support a varieties of 8-bit and some 16-bit 5-volt processors. Conceptually it is like G8PP, but it is a standalone platform with its own keyboard and video. It will be a nice platform to experimenting with the many processors I have in my part bins.
Bill
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