Re: Putting a ZX81 onto a CPLD
Posted: Wed Apr 19, 2017 11:39 am
A Simple ZX80 design using an inexpensive CPLD.
Below is the parts list for a simple ZX80 homebrew microcomputer, based around a simple and cheap CPLD (EPM7128SLC84-15) . The CPLD having 60+ I/O Lines and 128 macroccells . These are just examples to give people ideas of what can b e done for theoretically little money.
Z80 CPU (preferably )Z80B or better) clock speed 3.58Mhz,7.16MHz or better
32K SRAM (HM62256, approx 100ns , or Fast SRAM UM61256 15ns)
32K EEPROM/EPROM (27C256 approx 100ns , 28HC256 45ns or so)
CPLD (EPM7128-15 15ns 60+ I/O Lines, PLCC84 package)
8255 PIO for CF card or PATA IDE harddrive ( instead of Tape recorder)
DS12887 RTC (Real Time Clock with SRAM)
SN76489 Cheap Sound Chip
7805 Voltage Regulator
All Glue logic of original ULA and any extra functionality would be done by the CPLD (EPM8128SLC84). Video output can be produced via a resistor network for VGA Monitor, if TV output is designed then DACs with NTSC,PAL composite encoder will be needed. Pyroelectroincs has a section on using an EPM7128 as a video VGA generator...see :
Costing
Z80………...…..$1.50
SRAM……...…..$1.0
EPROM…….…..$1.0
CPLD ……….....$2.0
8255…………....$1.50
DS12887………..$1.50
SN76489…….....$0.50
7804 …………...$0.25
** Prices based on items on eBay.com
Total Cost <$10 for ICs , should be possible to make with switches, IC sockets , miscellaneous stuff & PCB for about $50
A Simple ZX81 design using an inexpensive CPLD.
Below is the parts list for a simple ZX81 homebrew microcomputer, based around a simple and cheap CPLD (EPM7160SLC84-10) . The CPLD having 60+ I/O Lines and 160 macroccells .
Z84C0020PEC ….Z80 CPU 3.58Mhz,7.16MHz upto 20MHz **
64K SRAM (UM6512-15 15ns))
64K EEPROM (W27C512-45 45ns)
CPLD (EPM7160SLC-10 10ns 60+ I/O Lines, PLCC84 package)
8255 PIO for CF card or PATA IDE harddrive ( instead of Tape recorder)
DS12887 RTC (Real Time Clock with SRAM)
SN76489 Cheap Sound Chip
AY-3-8910 or YM2149 Sound Chip
7805 Voltage Regulator
**Genuine 20MHz CPU can be got here :
tk-electronics
Optional
Z84C9008VSC PLCC Z80 KIO (CTC,PIO,SIO)
AM9511 Maths FPU
MB8877+WD9216 Floppy disc controllers
All Glue logic of original ULA and any extra functionality would be done by the CPLD (EPM7160SLC84). EPM7xxxSLC84 CPLDs can be programmed using a cheap (JTAG) USB Blaster cable.
Costing
Z80………...…..$1.90
SRAM……...…..$2.20
EPROM…….…..$1.0
CPLD ……….....$12.50
8255…………....$1.50
DS12887………..$1.50
SN76489…….....$0.50
AY-3-8910……...$1.50
7804 …………...$0.25
** Prices based on items on eBay.com
Total Cost <$24 for ICs , should be possible to make with switches, IC sockets , miscellaneous stuff & PCB for about $65
Below is the parts list for a simple ZX80 homebrew microcomputer, based around a simple and cheap CPLD (EPM7128SLC84-15) . The CPLD having 60+ I/O Lines and 128 macroccells . These are just examples to give people ideas of what can b e done for theoretically little money.
Z80 CPU (preferably )Z80B or better) clock speed 3.58Mhz,7.16MHz or better
32K SRAM (HM62256, approx 100ns , or Fast SRAM UM61256 15ns)
32K EEPROM/EPROM (27C256 approx 100ns , 28HC256 45ns or so)
CPLD (EPM7128-15 15ns 60+ I/O Lines, PLCC84 package)
8255 PIO for CF card or PATA IDE harddrive ( instead of Tape recorder)
DS12887 RTC (Real Time Clock with SRAM)
SN76489 Cheap Sound Chip
7805 Voltage Regulator
All Glue logic of original ULA and any extra functionality would be done by the CPLD (EPM8128SLC84). Video output can be produced via a resistor network for VGA Monitor, if TV output is designed then DACs with NTSC,PAL composite encoder will be needed. Pyroelectroincs has a section on using an EPM7128 as a video VGA generator...see :
Costing
Z80………...…..$1.50
SRAM……...…..$1.0
EPROM…….…..$1.0
CPLD ……….....$2.0
8255…………....$1.50
DS12887………..$1.50
SN76489…….....$0.50
7804 …………...$0.25
** Prices based on items on eBay.com
Total Cost <$10 for ICs , should be possible to make with switches, IC sockets , miscellaneous stuff & PCB for about $50
A Simple ZX81 design using an inexpensive CPLD.
Below is the parts list for a simple ZX81 homebrew microcomputer, based around a simple and cheap CPLD (EPM7160SLC84-10) . The CPLD having 60+ I/O Lines and 160 macroccells .
Z84C0020PEC ….Z80 CPU 3.58Mhz,7.16MHz upto 20MHz **
64K SRAM (UM6512-15 15ns))
64K EEPROM (W27C512-45 45ns)
CPLD (EPM7160SLC-10 10ns 60+ I/O Lines, PLCC84 package)
8255 PIO for CF card or PATA IDE harddrive ( instead of Tape recorder)
DS12887 RTC (Real Time Clock with SRAM)
SN76489 Cheap Sound Chip
AY-3-8910 or YM2149 Sound Chip
7805 Voltage Regulator
**Genuine 20MHz CPU can be got here :
tk-electronics
Optional
Z84C9008VSC PLCC Z80 KIO (CTC,PIO,SIO)
AM9511 Maths FPU
MB8877+WD9216 Floppy disc controllers
All Glue logic of original ULA and any extra functionality would be done by the CPLD (EPM7160SLC84). EPM7xxxSLC84 CPLDs can be programmed using a cheap (JTAG) USB Blaster cable.
Costing
Z80………...…..$1.90
SRAM……...…..$2.20
EPROM…….…..$1.0
CPLD ……….....$12.50
8255…………....$1.50
DS12887………..$1.50
SN76489…….....$0.50
AY-3-8910……...$1.50
7804 …………...$0.25
** Prices based on items on eBay.com
Total Cost <$24 for ICs , should be possible to make with switches, IC sockets , miscellaneous stuff & PCB for about $65