Difference between revisions of "SIMPLE-6502"

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Line 1: Line 1:
−
[[FILE:CPU-65C02_REV1_FRONT_(BLK).png]]
+
[[File:tindie-mediums.png|link=https://www.tindie.com/products/34959/]]
 +
 
 +
[[FILE:SIMPLE-6502_P1090254-720pxV.jpg]]
 +
 
 +
<video type="youtube">p5mwMwwM-R0</video>
  
 
== Features ==
 
== Features ==
Line 5: Line 9:
 
* Build of [http://searle.x10host.com/6502/Simple6502.html Grant Searles's Simple 6502 CPU]
 
* Build of [http://searle.x10host.com/6502/Simple6502.html Grant Searles's Simple 6502 CPU]
 
** Runs Microsoft (OSI) BASIC
 
** Runs Microsoft (OSI) BASIC
−
* 6502 CPU
+
* [https://github.com/land-boards/lb-boards/blob/master/RetroCPUs/SIMPLE-6502/PARTS/R65C02P3_Datasheet.pdf 65C02 CPU]
−
* 0.9216 or 1.8432 MHz clock
+
* 0.9216 or 1.8432 MHz clock - jumper selectable
−
* 32KB SRAM
+
* [https://github.com/land-boards/lb-boards/blob/master/RetroCPUs/SIMPLE-6502/PARTS/AS6C62256_23_March_2016_rev1_2-1288423.pdf 32KB SRAM]
 
* 16KB EPROM/EEPROM
 
* 16KB EPROM/EEPROM
−
* 68B50 Serial Port (ACIA)
+
** Using 1/2 of [https://github.com/land-boards/lb-boards/blob/master/RetroCPUs/SIMPLE-6502/PARTS/SST27SF256.pdf SST27SF256] - 32KB Flash Memory
−
** RS-232 port
+
* [https://github.com/land-boards/lb-boards/blob/master/RetroCPUs/SIMPLE-6502/PARTS/MC68B50_43633.pdf 68B50 Serial Port (ACIA)]
 +
** [https://github.com/land-boards/lb-boards/blob/master/RetroCPUs/SIMPLE-6502/PARTS/max232.pdf MAX232] RS-232 port or
 
** Header for FTDI
 
** Header for FTDI
 
** 115,200 baud
 
** 115,200 baud
−
* Reset switch with optional Power Supervisor
+
* Reset switch with optional [https://github.com/land-boards/lb-boards/blob/master/RetroCPUs/SIMPLE-6502/PARTS/ds1813-maxim%20integrated%20products_1178753.pdf DS1813 5V Power Supervisor]
 
* 95x95mm card
 
* 95x95mm card
 
* (4) 6-32 mounting holes
 
* (4) 6-32 mounting holes
Line 22: Line 27:
 
* 0x8000-0x9FFF Free Space (8KB)
 
* 0x8000-0x9FFF Free Space (8KB)
 
* 0xA000-0xBFFF Serial (ACIA)
 
* 0xA000-0xBFFF Serial (ACIA)
−
* 0xC000-0xCFFF 16KB EPROM
+
* 0xC000-0xFFFF 16KB EPROM
  
 
=== Chip Set ===
 
=== Chip Set ===
Line 30: Line 35:
 
[[file:LB_65C02_PARTS.jpg]]
 
[[file:LB_65C02_PARTS.jpg]]
  
−
* Used these parts:
+
* Picture shows 3 MHz CPU
 +
* Received 2 MHz CPU
 +
* As received:
  
 
[[file:SIMPLE-6502_P1090155-720px.jpg]]
 
[[file:SIMPLE-6502_P1090155-720px.jpg]]
Line 46: Line 53:
 
== Design ==
 
== Design ==
  
−
* CPU
+
=== CPU ===
  
 
[[file:U5_CPU_6502.PNG]]
 
[[file:U5_CPU_6502.PNG]]
  
−
* EPROM/EPROM
+
==== R6502 CPU Timing ====
 +
 
 +
[[file:R6502_Timing-01.PNG]]
 +
[[file:R6502_Timing-02.PNG]]
 +
 
 +
==== R65C02 vs W65C02 vs W65C816 CPUs ====
 +
 
 +
{| class="wikitable"
 +
! U5 Pin
 +
! U5 Pin Name
 +
! Sig Name
 +
! Pullup
 +
! R65C02 sig
 +
! W65C02 sig
 +
! W65C816 sig
 +
|-
 +
| 1
 +
| VSS/VPB
 +
| JP1 GNDs
 +
| N
 +
| VSS (IN)
 +
| VPB (OUT)
 +
| VPB (OUT)
 +
|-
 +
| 3
 +
| PH1OUT/ABORT
 +
| NC
 +
| N
 +
| PH1OUT (OUT)
 +
| PH1OUT (OUT)
 +
| ABORT (IN)
 +
|-
 +
| 5
 +
| NC/MLB
 +
| NC
 +
| N
 +
| NC
 +
| MLB (OUT)
 +
| MLB (OUT)
 +
|-
 +
| 7
 +
| SYNC/VPA
 +
| NC
 +
| N
 +
| SYNC (OUT)
 +
| SYNC (OUT)
 +
| VPA (OUT)
 +
|-
 +
| 35
 +
| NC/E
 +
| NC
 +
| N
 +
| NC
 +
| NC
 +
| EM/NAT (OUT)
 +
|-
 +
| 36
 +
| NC/BE
 +
| Pull up
 +
| Y
 +
| NC
 +
| BE (IN)
 +
| BE (IN)
 +
|-
 +
| 37
 +
| PH0IN/PH2IN
 +
| CPUCLK
 +
| N
 +
| PH0IN
 +
| PH2IN
 +
| PH2IN
 +
|-
 +
| 38
 +
| SO/MX
 +
| VCC
 +
| VCC
 +
| SO* (IN)
 +
| SOB (IN)
 +
| MX (OUT)
 +
|-
 +
| 39
 +
| PH2OUT/VDA
 +
| PH2_OUT
 +
| N
 +
| PH2OUT (OUT)
 +
| PH2OUT (OUT)
 +
| VDA(OUT)
 +
|-
 +
|}
 +
 
 +
* Need to lift U5-38 to use W65C816 CPU
 +
 
 +
[[file:R65C02_vs_W65C02_w65c816_Pinout_800PX.png]]
 +
 
 +
===== VDA/VPA (65C816) =====
 +
 
 +
* VDA/VPA
 +
** 00, Internal operation (invalid address bus)
 +
** 01, Valid Program Address
 +
** 10, Valid Data Address
 +
** 11, Opcode-fetch
 +
 
 +
=== EPROM/EPROM ===
 +
 
 +
* [[TL866ii Plus Programmer]]
  
 
[[file:U4_EEPROM.PNG]]
 
[[file:U4_EEPROM.PNG]]
  
−
* SRAM
+
=== SRAM ===
  
 
[[file:U2_SRAM.PNG]]
 
[[file:U2_SRAM.PNG]]
  
−
* Clock
+
=== Clock (Rev 1) ===
  
 
[[file:U7_U8_CLOCK.PNG]]
 
[[file:U7_U8_CLOCK.PNG]]
  
−
* UART
+
=== Clock (Rev 2) ===
 +
 
 +
[[file:U7_U8_CLOCK_v2.PNG]]
 +
 
 +
=== UART ===
 +
 
 +
* Can only use RS-232 or FTDI - one at a time
 +
** Put MAX232 in a socket if you want flexibility
 +
** Remove MAX232 if you want to use FTDI
  
 
[[file:U1_U3_UART.PNG]]
 
[[file:U1_U3_UART.PNG]]
  
−
* FTDI
+
=== FTDI ===
 +
 
 +
* Does not match Grant's pinout
 +
* Can only use RS-232 or FTDI - one at a time
  
 
[[file:J3_FTDI.PNG]]
 
[[file:J3_FTDI.PNG]]
Line 77: Line 199:
  
 
* DB-9 Male
 
* DB-9 Male
 +
* Matches Grant's pinout
 
* Pinout
 
* Pinout
  
Line 95: Line 218:
  
 
=== J3 - FTDI / TTL Serial ===
 
=== J3 - FTDI / TTL Serial ===
 +
 +
* Requires a FTDI cross-over cable
 +
 +
[[FILE:SIMPLE-6502_J3_FTDI.PNG]]
  
 
# GND
 
# GND
Line 112: Line 239:
  
 
[[FILE:SIMPLE-6502_J5_J6.PNG]]
 
[[FILE:SIMPLE-6502_J5_J6.PNG]]
 +
 +
* J5 - EPROM Pin 1 jumper
 +
** 1-2 for 28C64, 28C256 (Pull WE to VCC)
 +
** 2-3 for 27256, 27SF256, 27512 (Pull A14 to GND)
 +
* J6 - EPROM Pin 27 jumper
 +
** GND (2-3)
 +
 +
==== EEPROM Pin Table ====
  
 
{| class="wikitable"
 
{| class="wikitable"
 
! 27512
 
! 27512
 
! 27256
 
! 27256
 +
! 27SF256
 
! 28C256
 
! 28C256
 
! 27128
 
! 27128
Line 127: Line 263:
 
! 27128
 
! 27128
 
! 28C256
 
! 28C256
 +
! 27SF256
 
! 27256
 
! 27256
 
! 27512
 
! 27512
 
|-
 
|-
 
| A15
 
| A15
 +
| VPP
 
| VPP
 
| VPP
 
| A14
 
| A14
Line 139: Line 277:
 
|  
 
|  
 
| 28
 
| 28
 +
| VCC
 
| VCC
 
| VCC
 
| VCC
 
| VCC
Line 146: Line 285:
 
| VCC
 
| VCC
 
|-
 
|-
 +
| A12
 
| A12
 
| A12
 
| A12
 
| A12
Line 159: Line 299:
 
| PGM
 
| PGM
 
| WE*
 
| WE*
 +
| A14
 
| A14
 
| A14
 
| A14
 
| A14
 
|-
 
|-
 +
| A7
 
| A7
 
| A7
 
| A7
 
| A7
Line 173: Line 315:
 
| A13
 
| A13
 
| N/C
 
| N/C
 +
| A13
 
| A13
 
| A13
 
| A13
 
| A13
Line 178: Line 321:
 
| A13
 
| A13
 
|-
 
|-
 +
| A6
 
| A6
 
| A6
 
| A6
 
| A6
Line 187: Line 331:
 
|  
 
|  
 
| 25
 
| 25
 +
| A8
 
| A8
 
| A8
 
| A8
 
| A8
Line 194: Line 339:
 
| A8
 
| A8
 
|-
 
|-
 +
| A5
 
| A5
 
| A5
 
| A5
 
| A5
Line 203: Line 349:
 
|  
 
|  
 
| 24
 
| 24
 +
| A9
 
| A9
 
| A9
 
| A9
 
| A9
Line 210: Line 357:
 
| A9
 
| A9
 
|-
 
|-
 +
| A4
 
| A4
 
| A4
 
| A4
 
| A4
Line 219: Line 367:
 
|  
 
|  
 
| 23
 
| 23
 +
| A11
 
| A11
 
| A11
 
| A11
 
| A11
Line 226: Line 375:
 
| A11
 
| A11
 
|-
 
|-
 +
| A3
 
| A3
 
| A3
 
| A3
 
| A3
Line 235: Line 385:
 
|  
 
|  
 
| 22
 
| 22
 +
| OE*
 
| OE*
 
| OE*
 
| OE*
 
| OE*
Line 242: Line 393:
 
| OE*
 
| OE*
 
|-
 
|-
 +
| A2
 
| A2
 
| A2
 
| A2
 
| A2
Line 251: Line 403:
 
|  
 
|  
 
| 21
 
| 21
 +
| A10
 
| A10
 
| A10
 
| A10
 
| A10
Line 258: Line 411:
 
| A10
 
| A10
 
|-
 
|-
 +
| A1
 
| A1
 
| A1
 
| A1
 
| A1
Line 267: Line 421:
 
|  
 
|  
 
| 20
 
| 20
 +
| CE*
 
| CE*
 
| CE*
 
| CE*
 
| CE*
Line 274: Line 429:
 
| CE*
 
| CE*
 
|-
 
|-
 +
| A0
 
| A0
 
| A0
 
| A0
 
| A0
Line 283: Line 439:
 
|  
 
|  
 
| 19
 
| 19
 +
| D7
 
| D7
 
| D7
 
| D7
 
| D7
Line 290: Line 447:
 
| D7
 
| D7
 
|-
 
|-
 +
| D0
 
| D0
 
| D0
 
| D0
 
| D0
Line 299: Line 457:
 
|  
 
|  
 
| 18
 
| 18
 +
| D6
 
| D6
 
| D6
 
| D6
 
| D6
Line 306: Line 465:
 
| D6
 
| D6
 
|-
 
|-
 +
| D1
 
| D1
 
| D1
 
| D1
 
| D1
Line 315: Line 475:
 
|  
 
|  
 
| 17
 
| 17
 +
| D5
 
| D5
 
| D5
 
| D5
 
| D5
Line 322: Line 483:
 
| D5
 
| D5
 
|-
 
|-
 +
| D2
 
| D2
 
| D2
 
| D2
 
| D2
Line 331: Line 493:
 
|  
 
|  
 
| 16
 
| 16
 +
| D4
 
| D4
 
| D4
 
| D4
 
| D4
Line 338: Line 501:
 
| D4
 
| D4
 
|-
 
|-
 +
| GND
 
| GND
 
| GND
 
| GND
 
| GND
Line 347: Line 511:
 
|  
 
|  
 
| 15
 
| 15
 +
| D3
 
| D3
 
| D3
 
| D3
 
| D3
Line 364: Line 529:
 
* [http://searle.x10host.com/6502/osi_bas.zip Link to Grant's files]
 
* [http://searle.x10host.com/6502/osi_bas.zip Link to Grant's files]
 
* Source code
 
* Source code
−
** osi_bas.s <== the Microsoft OSI BASIC and I/O routines SOURCE all in a single file. My I/O routines are at the end of it.
+
** osi_bas.s <== the Microsoft OSI BASIC and I/O routines SOURCE all in a single file
 +
** Grant's I/O routines are at the end of it
 
* Files to allow the source to be assembled on a Windows based machine
 
* Files to allow the source to be assembled on a Windows based machine
−
** assemble.bat <== double click to assemble osi_bas.s and link to binary file "osi_bas.bin". This should be exactly 16K
+
** assemble.bat <== double click to assemble osi_bas.s and link to binary file "osi_bas.bin"
 +
** This should be exactly 16K
 
** osi_bas.cfg <== configuration file for the linker (ensure ORG and entries in this file match if you change any)
 
** osi_bas.cfg <== configuration file for the linker (ensure ORG and entries in this file match if you change any)
 
** ca65.exe <== the assembler from the cc65 package. Use this. The new version on the cc65 site crashes!
 
** ca65.exe <== the assembler from the cc65 package. Use this. The new version on the cc65 site crashes!
Line 379: Line 546:
 
** It is in standard INTEL-HEX format for uploading to a suitable programmer.
 
** It is in standard INTEL-HEX format for uploading to a suitable programmer.
  
−
== Mechanicals ==
+
== First Unit Checkout (Rev 1 PCB) ==
 +
 
 +
[[FILE:SIMPLE-6502_P1090185-720PX.jpg]]
 +
 
 +
=== Install Sockets ===
 +
 
 +
* Machined pin sockets
 +
 
 +
[[file:SIMPLE-6502_P1090153-720px.jpg]]
 +
 
 +
=== Install Passives ===
 +
 
 +
[[file:SIMPLE-6502_P1090159-720px.jpg]]
 +
 
 +
=== Power ===
 +
 
 +
* Install 2x4 at J4
 +
* Power card via J4 with 5V
 +
* Check power pins on parts
 +
 
 +
=== Clock ===
 +
 
 +
* Install Clock parts
 +
** Did not have 270 pF cap, used 220 pF
 +
** U7 (74HC04)
 +
** Y1 1.8432 MHz crystal
 +
** Clock "doubling" with 74HC04 part
 +
** Worse with 74HC14
 +
** Switched to 74LS04 - works well
 +
* Install clock divider
 +
** U8 (74HC74)
 +
* Check clocks at J2
 +
** Pin 1 s/b 0.9216 MHz
 +
** Pin 3 s/b 1.8432 MHz
 +
** Outputs are OK
 +
* Need to change P/L and S/S to 74LS04
 +
 
 +
[[FILE:SIMPLE-6502_CLK.png]]
 +
 
 +
* Clock does not start up reliably
 +
* Replaced part values with Fig 1d [https://www.changpuak.ch/electronics/datasheets/an12fa.pdf AN12 Circuit Techniques for Clock Sources]
 +
 
 +
[[FILE:AN12_Fig_1d.PNG]]
 +
 
 +
* Used 1nF cap instead of 1200pF
 +
* Starts reliably but has a glitch
 +
** Seems to run OK
 +
** Reset is weird, sometimes does not boot and takes a couple of presses
 +
** Not sure if this is clock related
 +
* Order new 74LS04 parts
 +
* See Rev 2 updates
 +
 
 +
=== Reset ===
 +
 
 +
* Install U9
 +
* Install pushbutton switch SW1
 +
* Reset button gets stretched by Power Monitor U9
 +
* Measure at 6502 U5 pin 40
 +
* Falling edge scope cap
 +
 
 +
[[file:SIMPLE-6502_RESET-FALLING.png]]
 +
 
 +
* Rising edge scope cap
 +
 
 +
[[file:SIMPLE-6502_RESET-RISING.png]]
  
−
[[FILE:SIMPLE-6502_REV1_MECHS.PNG]]
+
* Switch failed, replaced - works
  
−
== Checkout ==
+
=== EPROM ===
  
 
* SST27C256 EEPROM
 
* SST27C256 EEPROM
 
** 32 KB part
 
** 32 KB part
 
** Using first 16KB of EEPROM
 
** Using first 16KB of EEPROM
−
** Program using [[TL866ii_Plus_Programmer|TL-866ii plus programmer]]
 
−
** File = [https://github.com/land-boards/lb-boards/blob/master/RetroCPUs/SIMPLE-6502/SOFTWARE/ROM.HEX ROM.hex]
 
 
** J5 EEPROM pin 1 = VPP = VCC or GND
 
** J5 EEPROM pin 1 = VPP = VCC or GND
 
*** Jumper J5:2-3
 
*** Jumper J5:2-3
Line 395: Line 624:
 
*** Jumper J6:2-3
 
*** Jumper J6:2-3
 
* U1 - Do not install MAX232
 
* U1 - Do not install MAX232
−
** Use FTDI connector
+
** Use FTDI connector with [[FTDI-49MM]] card
−
** [[FTDI-49MM]]
+
* R65C02 CPU
 +
** Install JP1 on rear of card as wire
 +
 
 +
==== EEPROM Programming ====
 +
 
 +
* Program using [[TL866ii_Plus_Programmer|TL-866ii plus programmer]]
 +
* File = [https://github.com/land-boards/lb-boards/blob/master/RetroCPUs/SIMPLE-6502/SOFTWARE/ROM.HEX ROM.hex]
 +
* Got Device ID error
 +
* Turn off ID check
 +
 
 +
[[file:SIMPLE-6502_TL866Plus_Program.png]]
 +
 
 +
* Device programmed/verified
 +
 
 +
=== Install CPU, ROM, RAM, ACIA ===
 +
 
 +
* Do not install MAX232 yet
 +
** Use FTDI connector with [[FTDI-49MM]] card
 +
 
 +
=== Test FTDI Serial ===
 +
 
 +
* Wiring is '''not''' 1:1 to [[FTDI-49MM]]
 +
* Wire FTDI J3 to [[FTDI-49MM]] card
 +
** [[FTDI-49MM]] GND pin 1 to J3-1 RX on card
 +
** [[FTDI-49MM]] VCC pin 3 to J3-3 RX on card
 +
** [[FTDI-49MM]] TX pin 4 on to J3-5 RX on card
 +
** [[FTDI-49MM]] RX pin 5 on to J3-4 TX on card
 +
** [[FTDI-49MM]] CTS(in) pin 2 to J3-6 CTS on card
 +
* Hardware handshake doesn't work with [[FTDI-49MM]] card
 +
 
 +
=== Card Without MAX232 ===
 +
 
 +
* With DB-9 connector
 +
* Install DB-9 Male
 +
* Holes don't line up well, but 4-40 screws can fit
 +
* Without MAX232
 +
 
 +
[[file:SIMPLE-6502_P1090254-720pxV.jpg]]
 +
 
 +
=== Built Card ===
 +
 
 +
* With MAX232
 +
* Connected to [[FTDI-49MM]] and [[DCE]] cards
 +
** [[FTDI-49MM]] and [[DCE]] cards wired together
 +
** [[DCE]] has female DB-9
 +
** Separate power cable J2 on [[FTDI-49MM]] to J3 on card
 +
 
 +
[[FILE:FTDI_DCE_P1090192-720PXV.jpg]]
 +
 
 +
[[file:SIMPLE-6502_P1090192-720px.jpg]]
 +
 
 +
* DB-9 connectors connected together
 +
 
 +
[[file:SIMPLE-6502_P1090191-720px.jpg]]
 +
 
 +
* Works
 +
 
 +
[[file:SIMPLE-6502_Booting.png]]
 +
 
 +
== Performance ==
 +
 
 +
* TeraTerm settings
 +
 
 +
[[file:SIMPLE-6809_TeraTerm_Setup.PNG]]
 +
 
 +
* Test software
 +
 
 +
<pre>
 +
10 FOR I =1 TO 10000
 +
20 PRINT I
 +
30 NEXT I
 +
 
 +
</pre>
 +
 
 +
* Time ~38 secs
 +
 
 +
== Mechanicals ==
 +
 
 +
* Rev 1 board
 +
** Rev 2 board has the same mechanical dimensions, but some parts are different
 +
 
 +
[[FILE:SIMPLE-6502_REV1_MECHS.PNG]]
 +
 
 +
== PCB Issues ==
 +
 
 +
=== Rev 2 ===
 +
 
 +
* See clock section above for issues found during Rev 1 board checkout
 +
 
 +
[[File:SIMPLE-6502_Rev2_ClockUpdates.PNG]]
 +
 
 +
* R8, R9 missing 2.7K marking on silkscreen
 +
** Updated on Rev 2 interactive BOM
 +
* C6, C14 change value to 33 pF
 +
** Symptom with 22 pF caps was wrong oscillation frequency (approx 2.1 MHz)
 +
** Crystal is 18pF
 +
*** Matching caps should be 2x (since the caps are essentially in series
 +
*** 36pF would be right, but there's also pin and PCB capacitance so use 33 pF caps
 +
**** [https://www.iqdfrequencyproducts.com/blog/2020/08/03/myths-around-load-capacitance-how-to-choose-the-right-capacitors/ How to pick the right cap for oscillator]
 +
* U7 has to be 74HC04 with these other value parts
 +
* Measured oscillator circuit timing/voltages
 +
[[file:SIMPLE-6502_Rev2_Oscillator.png]]
 +
 
 +
=== Rev 1 ===
 +
 
 +
* Clocking not optimal - see notes above in clock section for debug issues
  
 
== Assembly Sheet ==
 
== Assembly Sheet ==
 +
 +
=== Assembly Sheet Rev 2 ===
 +
 +
* [http://land-boards.com/SIMPLE-6502/SIMPLE-6502_Rev2_ibom.html SIMPLE-6502 Rev 2 Interactive BOM]
 +
* Install jumper JP1 on rear of board if CPU is not a WDC 65C02 or WDC 65C816
 +
* Install jumpers J5-2 to -3 and J6-2 to -3
 +
* Clock changes from Grant's design
 +
* U7 is 74HC04 (silkscreen shows 74LS04)
 +
** 74LS04 might work if the Resistor values in the clock circuit are changed
 +
* Jumper J2 clock to run the CPU at either 1.8432 MHz or half speed 0.9216 MHz
 +
 +
=== Assembly Sheet Rev 1 ===
  
 
* [[SIMPLE-6502 Rev 1 Assembly Sheet]]
 
* [[SIMPLE-6502 Rev 1 Assembly Sheet]]
−
* [http://land-boards.com/SIMPLE-6502/SIMPLE-6502_Rev1_ibom.html Interactive BOM]
+
* [http://land-boards.com/SIMPLE-6502/SIMPLE-6502_Rev1_ibom.html SIMPLE-6502 Rev 1 Interactive BOM]

Latest revision as of 18:50, 28 August 2024

Tindie-mediums.png

SIMPLE-6502 P1090254-720pxV.jpg

Features

Memory Map

  • 0x0000-0x7FFF 32KB SRAM
  • 0x8000-0x9FFF Free Space (8KB)
  • 0xA000-0xBFFF Serial (ACIA)
  • 0xC000-0xFFFF 16KB EPROM

Chip Set

LB 65C02 PARTS.jpg

  • Picture shows 3 MHz CPU
  • Received 2 MHz CPU
  • As received:

SIMPLE-6502 P1090155-720px.jpg

References

Design

CPU

U5 CPU 6502.PNG

R6502 CPU Timing

R6502 Timing-01.PNG R6502 Timing-02.PNG

R65C02 vs W65C02 vs W65C816 CPUs

U5 Pin U5 Pin Name Sig Name Pullup R65C02 sig W65C02 sig W65C816 sig
1 VSS/VPB JP1 GNDs N VSS (IN) VPB (OUT) VPB (OUT)
3 PH1OUT/ABORT NC N PH1OUT (OUT) PH1OUT (OUT) ABORT (IN)
5 NC/MLB NC N NC MLB (OUT) MLB (OUT)
7 SYNC/VPA NC N SYNC (OUT) SYNC (OUT) VPA (OUT)
35 NC/E NC N NC NC EM/NAT (OUT)
36 NC/BE Pull up Y NC BE (IN) BE (IN)
37 PH0IN/PH2IN CPUCLK N PH0IN PH2IN PH2IN
38 SO/MX VCC VCC SO* (IN) SOB (IN) MX (OUT)
39 PH2OUT/VDA PH2_OUT N PH2OUT (OUT) PH2OUT (OUT) VDA(OUT)
  • Need to lift U5-38 to use W65C816 CPU

R65C02 vs W65C02 w65c816 Pinout 800PX.png

VDA/VPA (65C816)
  • VDA/VPA
    • 00, Internal operation (invalid address bus)
    • 01, Valid Program Address
    • 10, Valid Data Address
    • 11, Opcode-fetch

EPROM/EPROM

U4 EEPROM.PNG

SRAM

U2 SRAM.PNG

Clock (Rev 1)

U7 U8 CLOCK.PNG

Clock (Rev 2)

U7 U8 CLOCK v2.PNG

UART

  • Can only use RS-232 or FTDI - one at a time
    • Put MAX232 in a socket if you want flexibility
    • Remove MAX232 if you want to use FTDI

U1 U3 UART.PNG

FTDI

  • Does not match Grant's pinout
  • Can only use RS-232 or FTDI - one at a time

J3 FTDI.PNG

Headers / Connectors

SIMPLE-6502 REV1 CAD.PNG

J1 - RS-232 Serial

  • DB-9 Male
  • Matches Grant's pinout
  • Pinout
  1. N/C
  2. Receive
  3. Transmit
  4. Loop to pin 6
  5. GND
  6. Loop to pin 4
  7. RTS
  8. N/C
  9. N/C

J2 - Speed Select Jumper

  • 1-2 - 0.92 MHz
  • 2-3 = 1.8432 MHz

J3 - FTDI / TTL Serial

  • Requires a FTDI cross-over cable

SIMPLE-6502 J3 FTDI.PNG

  1. GND
  2. RTS* (out)
  3. +5V
  4. Receive (in)
  5. Transmit (out)
  6. N/C

J4 - 5V Power

  • 2x4 header

J4 PWR-5V.PNG

J5 / J6 - EPROM/EEPROM Select Jumpers

SIMPLE-6502 J5 J6.PNG

  • J5 - EPROM Pin 1 jumper
    • 1-2 for 28C64, 28C256 (Pull WE to VCC)
    • 2-3 for 27256, 27SF256, 27512 (Pull A14 to GND)
  • J6 - EPROM Pin 27 jumper
    • GND (2-3)

EEPROM Pin Table

27512 27256 27SF256 28C256 27128 2764 28C64 PIN PIN 2764 28C64 27128 28C256 27SF256 27256 27512
A15 VPP VPP A14 VPP VPP N/C 1 28 VCC VCC VCC VCC VCC VCC VCC
A12 A12 A12 A12 A12 A12 A12 2 27 PGM WE* PGM WE* A14 A14 A14
A7 A7 A7 A7 A7 A7 A7 3 26 A13 N/C A13 A13 A13 A13 A13
A6 A6 A6 A6 A6 A6 A6 4 25 A8 A8 A8 A8 A8 A8 A8
A5 A5 A5 A5 A5 A5 A5 5 24 A9 A9 A9 A9 A9 A9 A9
A4 A4 A4 A4 A4 A4 A4 6 23 A11 A11 A11 A11 A11 A11 A11
A3 A3 A3 A3 A3 A3 A3 7 22 OE* OE* OE* OE* OE* OE* OE*
A2 A2 A2 A2 A2 A2 A2 8 21 A10 A10 A10 A10 A10 A10 A10
A1 A1 A1 A1 A1 A1 A1 9 20 CE* CE* CE* CE* CE* CE* CE*
A0 A0 A0 A0 A0 A0 A0 10 19 D7 D7 D7 D7 D7 D7 D7
D0 D0 D0 D0 D0 D0 D0 11 18 D6 D6 D6 D6 D6 D6 D6
D1 D1 D1 D1 D1 D1 D1 12 17 D5 D5 D5 D5 D5 D5 D5
D2 D2 D2 D2 D2 D2 D2 13 16 D4 D4 D4 D4 D4 D4 D4
GND GND GND GND GND GND GND 14 15 D3 D3 D3 D3 D3 D3 D3

JP1 - CPU Pin 1

  • Install if CPU is not a WDC 65C02 or WDC 65C816

Software

  • Link to Grant's files
  • Source code
    • osi_bas.s <== the Microsoft OSI BASIC and I/O routines SOURCE all in a single file
    • Grant's I/O routines are at the end of it
  • Files to allow the source to be assembled on a Windows based machine
    • assemble.bat <== double click to assemble osi_bas.s and link to binary file "osi_bas.bin"
    • This should be exactly 16K
    • osi_bas.cfg <== configuration file for the linker (ensure ORG and entries in this file match if you change any)
    • ca65.exe <== the assembler from the cc65 package. Use this. The new version on the cc65 site crashes!
    • ld65.exe <== linker from the cc65 package
  • Output files
    • osi_bas.bin <== the ROM fine in pure binary
    • osi_bas.lst <== Assembly listing file
    • rom.hex <== the ROM fine in standard INTEL-HEX format
  • To allow simple re-assembly, extract all files to the same folder
    • Freeware utilities are available to convert the "bin" file to HEX or s19 (etc) - use your internet search tool to find
  • All source code, assembler binaries and the HEX dump of the ROM is here
    • It is in standard INTEL-HEX format for uploading to a suitable programmer.

First Unit Checkout (Rev 1 PCB)

SIMPLE-6502 P1090185-720PX.jpg

Install Sockets

  • Machined pin sockets

SIMPLE-6502 P1090153-720px.jpg

Install Passives

SIMPLE-6502 P1090159-720px.jpg

Power

  • Install 2x4 at J4
  • Power card via J4 with 5V
  • Check power pins on parts

Clock

  • Install Clock parts
    • Did not have 270 pF cap, used 220 pF
    • U7 (74HC04)
    • Y1 1.8432 MHz crystal
    • Clock "doubling" with 74HC04 part
    • Worse with 74HC14
    • Switched to 74LS04 - works well
  • Install clock divider
    • U8 (74HC74)
  • Check clocks at J2
    • Pin 1 s/b 0.9216 MHz
    • Pin 3 s/b 1.8432 MHz
    • Outputs are OK
  • Need to change P/L and S/S to 74LS04

SIMPLE-6502 CLK.png

AN12 Fig 1d.PNG

  • Used 1nF cap instead of 1200pF
  • Starts reliably but has a glitch
    • Seems to run OK
    • Reset is weird, sometimes does not boot and takes a couple of presses
    • Not sure if this is clock related
  • Order new 74LS04 parts
  • See Rev 2 updates

Reset

  • Install U9
  • Install pushbutton switch SW1
  • Reset button gets stretched by Power Monitor U9
  • Measure at 6502 U5 pin 40
  • Falling edge scope cap

SIMPLE-6502 RESET-FALLING.png

  • Rising edge scope cap

SIMPLE-6502 RESET-RISING.png

  • Switch failed, replaced - works

EPROM

  • SST27C256 EEPROM
    • 32 KB part
    • Using first 16KB of EEPROM
    • J5 EEPROM pin 1 = VPP = VCC or GND
      • Jumper J5:2-3
    • J6 EEPROM pin 27 = A14 = GND
      • Jumper J6:2-3
  • U1 - Do not install MAX232
  • R65C02 CPU
    • Install JP1 on rear of card as wire

EEPROM Programming

SIMPLE-6502 TL866Plus Program.png

  • Device programmed/verified

Install CPU, ROM, RAM, ACIA

  • Do not install MAX232 yet

Test FTDI Serial

Card Without MAX232

  • With DB-9 connector
  • Install DB-9 Male
  • Holes don't line up well, but 4-40 screws can fit
  • Without MAX232

SIMPLE-6502 P1090254-720pxV.jpg

Built Card

FTDI DCE P1090192-720PXV.jpg

SIMPLE-6502 P1090192-720px.jpg

  • DB-9 connectors connected together

SIMPLE-6502 P1090191-720px.jpg

  • Works

SIMPLE-6502 Booting.png

Performance

  • TeraTerm settings

SIMPLE-6809 TeraTerm Setup.PNG

  • Test software
10 FOR I =1 TO 10000
20 PRINT I
30 NEXT I
  • Time ~38 secs

Mechanicals

  • Rev 1 board
    • Rev 2 board has the same mechanical dimensions, but some parts are different

SIMPLE-6502 REV1 MECHS.PNG

PCB Issues

Rev 2

  • See clock section above for issues found during Rev 1 board checkout

SIMPLE-6502 Rev2 ClockUpdates.PNG

  • R8, R9 missing 2.7K marking on silkscreen
    • Updated on Rev 2 interactive BOM
  • C6, C14 change value to 33 pF
    • Symptom with 22 pF caps was wrong oscillation frequency (approx 2.1 MHz)
    • Crystal is 18pF
  • U7 has to be 74HC04 with these other value parts
  • Measured oscillator circuit timing/voltages

SIMPLE-6502 Rev2 Oscillator.png

Rev 1

  • Clocking not optimal - see notes above in clock section for debug issues

Assembly Sheet

Assembly Sheet Rev 2

  • SIMPLE-6502 Rev 2 Interactive BOM
  • Install jumper JP1 on rear of board if CPU is not a WDC 65C02 or WDC 65C816
  • Install jumpers J5-2 to -3 and J6-2 to -3
  • Clock changes from Grant's design
  • U7 is 74HC04 (silkscreen shows 74LS04)
    • 74LS04 might work if the Resistor values in the clock circuit are changed
  • Jumper J2 clock to run the CPU at either 1.8432 MHz or half speed 0.9216 MHz

Assembly Sheet Rev 1

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